K 


ECONOMIC   GEOLOGY 


WORKS   OF  PROF.  HEINRICH   RIES 

PUBLISHED    BY 

JOHN  WILEY  &  SONS,  Inc. 


Building  Stones  and  Clay  Products 

A  Handbook  for  Architects,  xiii+415  pages,  6  by 
9,  59  plates,  including  full-page  half-tones  and 
maps,  20  figures  in  the  text.  Cloth,  $3.00  net. 

Clays:  Their  Occurrence,  Properties  and  Uses 

With  Especial  Reference  to  Those  of  the  United 
States.  Second  Edition,  Revised,  xix-f  554  pages, 
6  by  9,  112  figures,  44  plates.  Cloth,  $5.00  net. 

Economic  Geology 

Fourth  Edition,  Rewritten,  xx+856  pages,  6  by  9, 
291  figures,  75  plates.  $4.00  net. 


By  RIES  AND  LEIGH  TON 

History    of    the    Clay    Working    Industry     in    the 
United  States 

By  Prof.  Heinrich  Ries,  and  Henry  Leighton,  Pro- 
fessor of  Economic  Geology,  University  of  Pitts- 
burgh. viii+270  pages,  6  by  9,  illustrated.  Cloth, 
$2.50  net. 

By  RIES  AND   WATSON 

Engineering  Geology 

By  Prof.  Heinrich  Ries,  and  Thomas  L.  Watson, 
Professor  of  Economic  Geology,  University  of  Vir- 
ginia, and  State  Geologist  of  Virginia,  xxvi+722 
pages,  6  by  9,  249  figures  in  the  text,  and  104  plates, 
comprising  175  figures.  Cloth,  $4.00  net. 


ECONOMIC  GEOLOGY 


BY 
HEINRICH   R1ES,  A.M.,  PH.D. 

PROFESSOR    OF    GEOLOGY    AT   CORNELL    UNIVERSITY 


FOURTH  EDITION,  THOROUGHLY  REVISED  AND  ENLARGED 


NEW  YORK 

JOHN  WILEY  &  SONS,    INC. 

LONDON:  CHAPMAN  &  HALL,  LIMITED 

1916 


COPYRIGHT,  1905,  1907,  1910, 
BY  THE  MACMILLAN  COMPANY 


COPYRIGHT,  1916, 
BY  HEINRICH  HIES 


PRESS    OF 

BRAUNWORTH   &   CO. 

g(5<JKBH>»DERS    AND    PRINTEW9 


PREFACE  TO   FOURTH   EDITION 


THE  continued,  advance  in  our  knowledge  of  Economic  Geology 
has  necessitated  considerable  revision  for  the  new  edition.  In 
addition,  the  author  has,  at  the  request  of  a  number  of  teachers, 
included  a  description  of  the  more  important  Canadian  mineral 
deposits,  as  well  as  brief  references  to  some  of  the  well-known  ones 
of  other  countries. 

While  these  additions  to  the  text  and  illustrations  have  increased 
the  size  of  the  book  somewhat,  the  number  of  pages  is  not  to  be 
taken  as  a  gauge  of  the  actual  increase  in  size,  for  the  reason  that 
over  one  hundred  full-page  illustrations,  formerly  bound  as  inserts, 
are  paged  in  with  the  text  in  the  present  edition. 

The  latest  available  statistics  have  been  included,  and  unless 
otherwise  stated  are  taken  from  the  United  States  Geological 
Survey,  and  Canadian  Department  of  Mines  reports. 

In  a  few  cases,  investigations  to  which  reference  rnight  have  been 
made  in  the  text  have  appeared  too  late  to  include  them,  but  it 
has  still  been  possible  to  insert  them  in  the  reference  list,  and  this 
has  been  done. 

The  author  takes  pleasure  here  in  acknowledging  his  deep  in- 
debtedness to  Professor  T.  L.  Watson  of  the  University  of  Vir- 
ginia, for  reading  and  criticising  the  manuscript.  Thanks  are 
also  due  to  Dr.  David  White  of  the  Geological  Survey,  for  criticis- 
ing the  data  contained  in  the  chart  on  page  26,  and  to  Mr.  H.  D. 
McCaskey  of  the  same  department,  for  aid  in  obtaining  statistical 
data. 

Acknowledgments  for  the  loan  of  new  illustrations  are  due  to 
Dr.  R.  G.  McConnell,  Deputy  Minister  of  Mines,  Canada;  Dr. 
E.  Haanel,  Director,  Mines  Branch,  Canada;  Professor  E.  C. 
Jeffrey,  Harvard  University,  Mr.  F.  W.  DeWolf,  State  Geologist, 
Illinois;  The  Southern  Railway  Company;  Mr.  F.  C.  Wallower, 
Webb  City,  Mo.,  and  Mr.  J.  S.  Hook,  Cornell  University.  The 
latter  also  kindly  took  all  of  the  photomicrographs  made  for  this 
edition. 

CORNELL  UNIVERSITY,  ITHACA,  N.  Y. 
June,  1916 

iii 


CONTENTS 


PART  I.    NONMETALLICS 

CHAPTER  PAGE 

-   I.  Coal 1 

*-  II.  Petroleum,  Natural  Gas,  and  other  Hydrocarbons 70 

III.  Building  Stones 138 

IV.  Clay . . .  r 170 

V.  Limes  and  Calcareous  Cements 187 

-  VI.  Salines  and  Associated  Substances 210 

VII.  Gypsum 244 

VIII.  Fertilizers 260 

IX.  Abrasives 284 

X.  Minor  Minerals.     Asbestos — Glass  Sand 298 

XI.  Minor  Minerals.     Graphite — Monazite 344 

XII.  Minor  Minerals.     Precious  Stones— Wavellite 380 

XIII.  Underground  Waters 416 

•~i>; 

PART   II.     ORE   DEPOSITS 

XIV.  Ore  Deposits '. 429 

XV.  Iron  Ores 502 

XVI.  Copper 568 

XVII.  Lead  and  Zinc 621 

XVIII.  Silver  Lead  Ores 658 

XIX.  Gold  and  Silver 676 

XX.  Minor  Metals.    Aluminum,  Manganese,  Mercury 750 

XXI.  Minor  Metals.    Antimony  to  Vanadium 779 

v 


LIST  OF  ILLUSTRATIONS 


FIG.  PAGE 

1.  Diagram  showing  changes  occurring  in  passage  of  vegetable  tissue  to 

graphite 18 

2.  Section  in  Coal  Measures  of  western  Pennsylvania,  showing  fireclay 

under  coal  beds 22 

3.  Section  showing  irregularities  in  coal  seam 23 

4.  Section  of  faulted  coal  seam 23 

5.  Section  of  coal  bed,  showing  the  development  of  a  split,  due  to  an 

overthrust  roll 24 

6.  Section  across  Coosa,  Ala.,  coal  field,  showing  folding  and  faulting 

characteristic  of  southern  end  of  Appalachian  coal  field 29 

7.  Map  of  Pennsylvania  anthracite  field 30 

8.  Sections  in  Pennsylvania  anthracite  field 30 

9.  Coal  breaker  in  Pennsylvania  anthracite  region 31 

10.  Structure  section  in  Tazewell  County,  east  of  Richlands,  southwest 

Virginia  coal  field 34 

11.  General  structure  section  of  the  Richmond  basin  in  the  vicinity  of 

the  James  River 35 

12.  Section  across  Eastern  Interior  coal  field 36 

13.  Shaft  house  and  tipple,  bituminous  coal  mine,  Spring  Valley,  111 37 

14.  Generalized  section  of  Northern  Interior  coal  field 38 

15.  Composite  section  showing  structure  of  Lower  Coal  Measures  of 

Iowa 38 

16.  Columnar  section  of  coal-bearing  rocks  in  Oklahoma  coal  field 40 

17.  Generalized  columnar  section  of  the  coal-bearing  rocks  of  Arkansas .  .  41 

18.  Map  showing  distribution  of  different  kinds  of  coal  in  Colorado 44 

19.  Map  showing  distribution  of  different  kinds  of  coal  in  Wyoming.  ...  45 

20.  Geologic  sections  in  southeastern  part  of  Anthracite,  Colo.,  sheet. ...  46 

21.  Map  of  Alaska,  showing  distribution  of  coal  and  coal-bearing  rocks.  .  47 

22.  Map  showing  coal  areas  of  Nova  Scotia 48 

23.  Map  showing  coal  areas  of  Western  Canada 49 

24.  Yearly  production  of  anthracite  and  bituminous  coal  from  1856  to  1908  58 

25.  Diagram  showing  how  plants  fill  depressions  from  the  sides  and  top  to 

form  a  peat  deposit 61 

26.  Sections  of  wells  southeast  of  Humboldt,  Kas 83 

27.  Sections  of  deep  wells  in  Claysville,  Pa.,  quadrangle,  showing  irregu- 

larity in  thickness  and  number  of  the  oil  and  gas  sands 84 

28.  Section  of  anticlinal  fold  showing  accumulation  of  gas,  oil  and  water .  .  87 

29.  Contour  map  of  "  sand,"  showing  occurrence  of  gas  on  a  structural 

dome  in  Oklahoma 88 

vii 


viii  LIST   OF    ILLUSTRATIONS 

FIG.  PAGE 

30.  Gas  pool  coincident  with  a  structural  terrace 88 

31.  Hypothetical  cross-section  through  a  volcanic  neck  in  the  oil  fields  of 

Vera  Cruz  and  Tamaulipas,  Mexico 90 

32.  Hypothetical  section  in  same  district  as  Fig.  31 90 

33.  Map  showing  lines  of  sections  in  Plate  XI 94 

34.  Diagrammatic  section  of  sands  in  the  central  Appalachian  region ....  95 

35.  Geologic  section  of  Ohio-Indiana  oil  and  gas  fields 98 

36.  Map  of  Illinois  showing  distribution  of  oil  fields 100 

37.  Map  of  California  oil  fields  and  pipe  lines 103 

38.  North-south   section,    showing   structure   of   western   field   of   Los 

Angeles  district 104 

39.  Section  of  Spindle  Top  oil  field  near  Beaumont,  Tex 106 

40.  Generalized  section  from   Paleozoic  outcrop  in  Arkansas  through 

Caddo  oil  field,  and  Sour  Lake  to  Galveston,  Tex 107 

41.  Map  of  Wyoming,  showing  approximately  the  areas  underlain  by  oil 

and  gas 108 

42.  Section  across  portion  of  oil  district  of  southwestern  Wyoming 109 

43.  Map  of  Alaska,  showing  areas  in  which  oil  or  gas  are  known  to  occur .  110 

44.  Map  of  Mexico  oil  field 112 

45.  Section  in  Mexico  oil  field 112 

46.  Map  of  asphalt  and  bituminous  rock  deposits  of  the  United  States.  .  117 

47.  Map   showing  relation   of   grahamite   fissure   to   anticlinal  fold,  in 

Ritchie  County,  W.  Va 120 

48.  Plan  of  Trinidad  pitch  lake 121 

49.  Section  of  gilsonite  vein,  Utah 121 

50.  Gilsonite  mine  at  Dragon,  Utah 122 

51.  Chart  of  oil  production 127 

52.  Photo-micrograph  of  a  section  of  granite 139 

53.  Photo-micrograph  of  a  section  of  diabase 140 

54.  Photo-micrograph  of  a  section  of  quartzitic  sandstone 142 

55.  Map  showing  distribution  of  crystalline  rocks  (mainly  granites)  in  the 

United  States 147 

56.  Map  showing  marble  areas  of  eastern  United  States 152 

57.  Section  showing  cleavage  and  bedding  in  slate 159 

58.  Section  in  slate  quarry  with  cleavage  parallel  to  bedding 160 

59.  Map  showing  distribution  of  slate  in  the  United  States 161 

60.  Section  showing  formation  of  residual  clay 170 

61.  Section  of  a  sedimentary  clay  deposit 171 

62.  Geologic  map  of  the  Vlightberg  area,  Rondout,  N.  Y 197 

63.  Geologic  sections  through  the  Vlightberg,  showing  position  of  natural 

rock  cement  beds 19g 

64.  Section  in  cement  quarries  at  Utica,  111 198 

65.  Map  of  cement  belt  of  eastern  Pennsylvania 199 

66.  Diagrammatic  section  two  miles  long  extending  northwest  from  Mar- 

tin's Creek,  N.  J.,  showing  overturned  folds 200 

67.  Diagrammatic  section  five  miles  long,   extending  northwest  from 

Catasauqua 200 

68.  Map  of  United  States,  showing  location  of  cement  plants 201 

69.  Chart  showing  production  of  cement 204 


LIST    OF    ILLUSTRATIONS  ix 


FIO. 

70.  Figures  representing  the  origin  of  dome  structure  by  crystalline 

growth  ....................................................   217 

71.  Map  showing  distribution  of  salt-producing  areas  in  the  United 

States  .....................................................   218 

72.  Section  showing  number  and  thickness  of  salt  beds  at  different 

localities  in  New  York  state  ...................................   221 

73.  Section  across  Holston  and  Saltville  valleys,  midway  between  Salt- 

ville  and  Plasterco,  Va  .......................................  222 

74.  Geologic  section  from  Arkansas  City  to  Great  Bend,  Kas.,  showing 

occurrence  of  rock  salt  .......................................  223 

75.  Map  showing  location  of  Petit  Anse  and  other  salt  islands,  Louisiana  223 

76.  Section  illustrating  dome  salt  occurrence,  under  Cedar  Lick,  La.  .  .  .   224 

77.  Map  showing  borax  deposits  of  the  United  States  ................   234 

78.  Cross-section  of  Furance  Canon,  Calif.,  borate  deposits  ...........   235 

79.  Map  showing  Owens  and  neighboring  lakes  of  California  .........   240 

80.  Map  showing  gypsum-producing  localities  of  the  United  States  .....   248 

81.  Map  of  New  York,  showing  outcrop  of  gypsum-bearing  formations  .   249 

82.  Section  of  gypsum  deposit  at  Linden,  N.  Y  .......................  250 

83.  Map  showing  location  of  gypsum  areas  in  Canada  .................   254 

84.  Map  showing  phosphate  areas  of  Florida  ...............  .  .........   264 

85.  Map  showing  distribution  of  phosphates  in  Tennessee  ............   267 

86.  Vertical  section  showing  geologic  position  of  Tennessee  phosphates.  268 

87.  Sections  showing  development  of  "  cutters"  of  brown  phosphate.   270 

88.  Map  of  parts  of  Idaho,  Wyoming  and  Utah,  showing  localities  of 

Upper  Carboniferous  rocks  containing  phosphate  beds  ...........   273 

89.  Columnar  sections  showing  position  and  richness  of  western  phos- 

phate beds  ..........................................  .  .......  274 

90.  Section    showing    structure    of    phosphate-bearing    formations  in 

Wyoming  ........................................  .  .........  275 

91.  Section  of  Carboniferous  strata  on  north  side  of  Montpelier  Creek, 

Idaho  .....................................................  275 

92.  (a)  Section  of  oolitic  phosphate,  Cokeville,  Wyo.     (6)  Section  of 

Bigby  limestone,  brown  phosphate  district,  Tenn  ................   277 

93.  Section  in  Lafferty  Creek,  Ark.,  phosphate  district  ...............  278 

94.  North-south  section  through  Missouri  and  Statehouse  Mountains, 

showing  folded  character  of  novaculite  and  slate-bearing  forma- 
tions of  Arkansas  ...........................................  288 

95.  Volcanic  ash  from  Madison  County,  Mont  .......................   288 

96.  Section  showing  occurrence  of  corundum  around  border  of  dunite 

mass  .....................................................  293 

97.  Map  showing  asbestos  districts  of  the  United  States  .  .  ...........  299 

98.  Asbestos  vein  in  serpentine  ...................................  300 

99.  Geologic  map  of  Vermont  asbestos  area  ..........  .  .............   301 

100.  Map  of  Quebec  asbestos  area  ..................................  302 

101.  Photomicrograph  of  asbestos  vein  ...............................  304 

102.  Diagram  showing  asbestos  and  serpentine  in  peridotite  ...........  306 

103.  Map  of  barite  deposits  of  Appalachian  states  ....................  311 

104.  Barite  veins  in  Potosi  dolomite,  southeastern  Missouri  ...........  311 

105.  Barite  deposit  in  residual  clay  near  Mineral  Point,  Mo  ...........  312 


FIG. 


LIST    OF    ILLUSTRATIONS 

PAGE 

106.  Map  of  Virginia,  showing  location  of  worked  areas  of  barite 312 

107.  Ideal  sections  in  Bennett  barite  mine,  Pittsylvania  County,  Va. .  .  .  313 

108.  Map  of  barite  veins  near  Lexington,  Ky 314 

109.  Sections  of  Kentucky  barite  vein 314 

110.  Sketch  section  showing  relations  of  barite  and  limonite  to  under- 

lying formations  near  Cartersville,  Ga 315 

111.  Diatomaceous  earth  from  Lompoc,  Calif 319 

112.  Section  of  Memphis  mine  group,  along  line  ss  of  Plate  XXXIV.  .  .  .  328 

113.  Map  and  sections  of  fluorspar  deposits  at  Deming,  N.  Mex 330 

114.  Map  showing  principal  graphite  areas  of  northeastern  states 347 

115.  Map  of  Bavarian  graphite  deposits 350 

116.  Map  of  part  of  California  showing  distribution  of  magnesite  deposits  358 

117.  Plan  of  magnesite  veins  and  workings  four  miles  northeast  of 

Porterville,  Calif 359 

118.  Map  showing  areas  in  North  Carolina  in  which  mica  has  been  mined  366 

119.  Section  across  pegmatite  at  Thorn  Mountain  mine,  Macon  Co.,  N.C.  366 

120.  Generalized  cross-section  of  No.  1  or  New  York  Mine,  near  Custer, 

S.D 367 

121.  Section  showing  relations  of  ocher,  quartzite  and  clay,  near  Car- 

tersville, Ga 372 

122.  Map  showing  area  of  monazite  deposits  of  known  commercial  value 

in  southern  Appalachian  region 378 

123.  Map  of  Arkansas  diamond  area 381 

124.  Section  in  Arkansas  diamond  area 381 

125.  Section  showing  stratigraphy  and  structure  from  crest  of  Owl  Creek 

Mountains  to  Owl  Creek,  and  relations  of  sulphur  deposits  near 
Thermopolis,  Wyo 397 

126.  Section  in  Sicilian  sulphur  deposits 398 

127.  Banded  sulphur-bearing  rock  from  Sicily 398 

128.  Plan  of  pyrite  lenses  at  Sulphur  Mines,  Louisa  County,  Va.,  showing 

pyrite  (a)  and  crystalline  schists  (6) 401 

129.  Plan  of  pyrite  lens  (a),  showing  stringers  of  pyrite,  interleaved  with 

schists  (6)  on  hanging  wall 402 

130.  Section  of  talc  deposit  near  Tecopa,  Calif 410 

131.  Ideal  section  across  a  river  valley,  showing  the  position  of  ground 

water  and  the  undulations  of  the  water  table  with  reference  to  the 
surface  of  the  ground  and  bed  rock 416 

132.  Section  showing  effect  of  tide  on  level  of  water  table 417 

133.  Geologic  section  of  Atlantic  coastal  plain,  showing  water-bearing 

horizons 420 

134.  Section  from  Black  Hills  across  South  Dakota,  showing  artesian 

water  circulations 420 

135.  Section  of  chromite  in  olivine  partly  altered  to  serpentine 431 

136.  Section  through  a  contact-metamorphic  zone  and  ore  body 448 

137.  Section  of  garnetiferous  limestone  from  Silver  Bell,  Ariz 450 

138.  Breccia  of  schist,  in  part  replaced  by  sphalerite,  and  cemented  by 

quartz 462 

139.  Photo-micrograph  of  a  section  of  quartz  conglomerate,  showing 

replacement  of  quartz  by  pyrite 463 


LIST   OF    ILLUSTRATIONS  xi 


140.  Thin  section  showing  replacement  of  hornblende  by  pyrite 463 

141.  Replacement  vein  in  syenite  rock,  War  Eagle  Mine,  Rossland,  B.  C.  464 
142. 1  Photo-micrographs  of  thin  sections  of  sulphide  ore  from  Austin ville, 

143.  i     Va 465 

144.  Section  of  vein  in  Enterprise  Mine,  Rico,  Colo 468 

145.  Section  showing  change  in  character  of  vein  passing  from  gneiss 

to  porphyry 470 

146.  Tabulation  of  strikes  of  principal  veins  in  Monte  Cristo,  Wash., 

district 470 

147.  Linked  veins 471 

148.  Gash  vein  with  associated  flats  and  pitches.     Wisconsin  zinc  region .   472 

149.  Section  at  Bonneterre,  Mo.,  showing  ore  disseminated  through  lime- 

stone    473 

150  1 

151*  |  Sketches  showing  dimensions  of  an  ore  shoot 473 

152.  Section  through  Copper  Queen  orebody,  Bisbee,  Arizona 475 

153.  Map  showing  distribution  of  hematite  and  magnetite  deposits  in 

United  States .   505 

154.  Geologic  map  of  Adirondack  region,  New  York,  showing  location  of 

iron-ore  deposits 506 

155.  Map  of  Mineville,  N.  Y.,  iron  ore  district 507 

156.  Thin  section  of  magnetite  gneiss,  Lyon  Mountain,  N.  Y 508 

157.  Sections  of  the  Old,  21-Bonanza-Joker,  orebeds,  Mineville,  N.  Y. .  .  510 

158.  Geologic  column  of  the  Iron  Springs,  Utah,  district 513 

159.  Map  of  a  portion  of  the  Iron  Springs,  Utah,  district 514 

160.  Cross-section  of  Desert  Mound  contact  deposit,  Iron  Springs,  Utah  515 

161.  Photomicrograph  of  ore  from  Kiruna,  Sweden 517 

162.  Section  through  Luossavara,  near  Kiruna,  Sweden 518 

163.  Map  of  Iron  Mountain,  Wyo.,  titaniferous  magnetite  deposit 523 

164.  Section  of  titaniferous  magnetite  from  Cumberland,  R.  1 523 

165.  Map  of  Lake  Superior  iron  regions 529 

166.  Sections  of  iron  ore  deposits  in  Marquette  range 530 

167.  Generalized  vertical  section  through  Penokee-Gogebic  ore  deposit 

and  adjacent  rocks 530 

168.  Generalized  vertical  section  through  Mesabi  ore  deposit  and  adja- 

cent rocks 532 

169.  Map  of  eastern  United  States,  showing  areas  of  Clinton  iron  ore.  .  .  .  540 

170.  Map  showing  outcrop  of  Clinton  ore  in  Alabama 541 

171.  Outcrop  of  Clinton  iron  ore,  Red  Mountain,  near  Birmingham,  Ala.  542 

172.  Map  showing  outcrop  of  Clinton  ore  formation  in  New  York  state .  .  544 

173.  Typical  profile  of  slope  on  Red  Mountain,  Ala 545 

174.  Map  showing  distribution  of  limonite  and  siderite  in  the  United 

States 550 

175.  Map  showing  location  of  iron-ore  deposits  in  Virginia 550 

176.  Geologic  section  showing  position  of  iron-ore  deposits  in  Virginia .  .   552 

177.  Vertical  section  showing  structure  of  the  valley  brown-ore  deposits 

at  the  Rich  Hill  mine,  near  Reed  Island,  Va 553 

178.  Section  of  fractured  quartzite  from  residual  limonite  deposit,  Pitts- 

ville,  Va 554 


xii  LIST    OF    ILLUSTRATIONS 

FIG.  PAGE 

179.  Section  illustrating  the  formation  of  residual  limonite  in  limestone . .  555 

180.  Section  of  Oriskany  limonite  deposit 555 

181.  Thin  section  of  oolitic  iron  ore  (mineUe)  from  Luxembourg 558 

182.  Diagram  showing  the  production  of  iron  ore,  pig  iron  and  steel  in 

the  United  States 560 

183.  Map  of  Arizona,  showing  location  of  more  important  mining  districts  574 

184.  Geologic  sections  of  Bisbee,  Ariz.,  district 575 

185.  Geologic  section  at  Bisbee,  Ariz 576 

186.  Geologic  map  of  vicinity  of  Morenci,  Ariz 577 

187.  Section  in  Morenci,  Ariz.,  district 578 

188.  Photo-micrograph  showing  replacement  in  Clifton-Morenci  ores . . .  578 

189.  Vertical  section  of  ore  body  in  Clifton-Morenci  district 579 

190.  Photo-micrograph  of  altered  porphyry  containing  grains  of  pyrite. .  582 

191.  Section  showing  replacement  of  limestone  by  pyrite  and  chalcopyrite, 

Bingham  Canon,  Utah 584 

192.  Section  of  Ely,  Nev.,  district 586 

193.  Geologic  map  of  Copper  Mountain  region,  Prince  of  Wales  Island, 

Alaska 588 

194.  Section  through  ore  deposit  at  Phoenix,  Brit.  Col 590 

195.  Photo-micrograph  of  section  of  Phoenix  ore 591 

196.  Section  through  Mother  Lode  ore  body,  Deadwood,  Brit.  Col. .  .  .   591 

197.  Map  of  eastern  part  of  Butte,  Mont.,  district,  showing  ore  veins 

and  geology 594 

198.  Generalized  cross-section  of  Butte  district,  Montana 595 

199.  Longitudinal  vertical  projection  of  High  Ore  Vein,  Butte,  Mont ....  596 

200.  Plan  of  500-foot  level,  Pennsylvania  Mine,  Butte,  Mont 598 

201.  Geologic  map  of  western  half  of  Butte  district 599 

202.  Vertical  section  showing  ore  body  in  schist,  Mineral  Creek,  Ariz., 

district 601 

203.  Geologic  map  of  a  portion  of  the  Mineral  Creek,  Ariz.,  district.  .  .  .  601 

204.  Copper  vein  at  Virgilina,   Va 602 

205.  Generalized  northwest-southeast  section,  including  Isle  Royal  and 

Keweenaw  Point 604 

206.  Section  across  Michigan  copper  belt 604 

207.  Map  of  a  portion  of  Michigan  copper  district,  showing  strike  of  the 

lodes : 605 

208.  Section  showing  occurrence  of  amygdaloidal  copper,  Quincy  Mine, 

Mich 606 

209.  Plan  of  ore  bodies,  Ducktown,  Tenn 611 

210.  Map  of  Carroll  County,  Va.,   pyrrhotite  area 612 

211.  Section  of  ore  from  Chestnut  Yard,  Va 612 

212.  Map  showing  distribution  of  lead  and  zinc  ores  in  the  United  States .   624 

213.  Model  of  Franklin  ore  body 626 

214.  Plan  of  outcrop  and  workings  of  Sterling  Kill  ore  body 627 

215.  Ideal  Section  of  Leadville,  Colo.,  district 630 

216.  Vertical  section  along  line  AB  of  Fig.  217,  Tucson  shaft,  Leadville, 

Colo 633 

217.  Geologic  plan  of  fifth  level  and  workings,  Tucson  shaft,  Leadville, 

Colo .634 


LIST   OF    ILLUSTRATIONS  xiii 

FIG.  PAGE 

218.  Cavities  in  Cambrian  quartzite,  Tucson  shaft,  Leadville,  Colo 635 

219.  Section  of  oxidized  ore  deposits,  Bertha  mine,  Austinville,  Va 638 

220.  Section  showing  replacement  of  limestone  by  sphalerite  and  galena, 

Austinville,  Va 639 

221.  Map  of  Ozark  region 639 

222.  General  west-east  section  through  Joplin  and  St.  Francis  Mountains, 

Mo 640 

223.  General  north-south  section  through  Springfield  and  Sedalia,  Mo. .  .   640 

224.  Generalized  geologic  section  of  Joplin  district 641 

225.  Photomicrograph  of  jasperoid 642 

226.  Four  and  one-half  foot  section  showing  occurrence  of  ore  in  Bonne- 

terre  limestone,  Doe  Run,  Mo 647 

227.  Section  showing  occurrence  of  lead  and  zinc  ore  in  Wisconsin 649 

228.  Map  of  a  portion  of  Wisconsin  lead  and  zinc  district,  showing  strike 

of  crevices,  underground  contours  of  Galena  limestone,  and  under- 
ground workings 650 

229.  Map  showing  location  of  Cceur  d'Alene,  Idaho,  district 660 

230.  Geologic  map  of  Cceur  d'Alene,  Ido.,  district 662 

231.  Section  of  lead-silver  vein,  Cceur  d'Alene,   Ido 663 

232.  Map  of  Nevada,  showing  location  o2  more  important  mining  dis- 

tricts    665 

233.  Geologic  map  of  Tintic  district,  Utah 666 

234.  Section  of  ore  body  at  Aspen,  Col 669 

235.  Diagrammatic  section  across  a  northeasterly  lode  at  Rico,  Col 670 

236.  Vein  filling  a  fault  fissure,  Enterprise  mine,  Rico,  Col 671 

237.  Map  showing  distribution  of  gold  and  silver  ores  in  the  United  States  681 

238.  Map  of  California  showing  location  of  more  important  mining 

districts 683 

239.  Section  at  Hedley,  B.  C.,  showing  contact-metamorphic  gold  ore 

bodies 688 

240.  Section  of  Homestake  belt  at  Lead,  S.  Dak 690 

241.  Map  showing  mineral  deposits  of  Alaska 692 

242.  Sketch  map  of  Douglas  Island,  Alaska 693 

243.  Cross-section  through  Alaska  Treadwell  mine  on  northern  side  of 

Douglas  Island 694 

244.  Map  and  section  of  portion  of  Mother  Lode  district,  Calif . 696 

245.  Section  illustrating  relations  of  auriferous  quartz  veins  at  Nevada 

City,  Calif 698 

246.  Map  of  Utah,  showing  location  of  more  important  mining  districts .  .   700 

247.  Typical  section  of  siliceous  gold  ores,  Black  Hills,  S.  Dak 701 

248.  Section  at  Mercur,  Utah 701 

249.  Map  showing  approximate  distribution  of  principal  silver,  lead  and 

gold  regions  of  Colorado 702 

250.  Map  showing  veins  and  porphyry  dikes  in  the  Silver  Plume,  Col.,  re- 

gion   703 

251.  Map  of  Colorado  showing  location  of  mining  regions 705 

252.  Section  across  the  Goldenville  district,  Nova  Scotia 706 

253.  Transverse  section  of  a  part  of  the  West  Lake  Mine,  Mount  Uniake  707 

254.  Geologic  section  across  the  Goldfield,  Nev.,  district 708 


xiv  LIST   OF    ILLUSTRATIONS 

FIG. 

255.  Geologic  map  of  Goldfield,  Nev.,  district 709 

256.  Generalized  columnar  section  of  geological  formations  at  Goldfield, 

Nev 710 

257.  Map  showing  outcrops  of  siliceous  ledges  east  of  Goldfield,  Nev 712 

258.  Geologic  surface  map  of  producing  area  of  Tonopah 715 

259.  East-west  section  through  Mizpah  shaft,  Tonopah 716 

260.  Section  of  Comstock  Lode 718 

261.  Sections  showing  possible  outline  of  the  Cripple  Creek  volcanic 

cone  at  the  close  of  the  volcanic  epoch 719 

262.  Sections  of  vein  at  Cripple  Creek,  Colo 720 

263.  Vertical  section  through  the  Burns  shaft,  Portland  Mine,  Cripple 

Creek,  Colo 721 

264.  Geologic   section   across  the   northwest  portion   of   the   Telluride 

quadrangle 724 

265.  Geologic  map  of  Telluride  district,  Colorado 726 

266.  Generalized  section  of  old  placer  with  technical  terms 732 

267.  Geologic  map  of  Alabama-Georgia  bauxite  region 752 

268.  Section  of  bauxite  deposit  in  Georgia- Alabama  belt 752 

269.  Generalized  cross-sections  illustrating  the  geologic  history  of    the 

Arkansas  bauxite  occurrences 755 

270.  Sections  of  manganese  deposit,  Crimora,  Va 762 

271.  Map  showing  Georgia  manganese  areas 762 

272.  Section  of  Georgia  manganese  area 764 

273.  Section  in  Batesville,  Ark.,  manganese  region 766 

274.  Map  of  California  mercury  localities 773 

275.  Map  showing  Texas  mercury  region 774 

276.  Vertical  section  of  California  Hill,  Terlingua,  Tex 775 

277.  Section  of  cinnabar  vein  in  limestone 775 

278.  Thin  section  of  limestone  impregnated  and  replaced  by  cinnabar .  .  776 

279.  Map  showing  chromic  iron  ore  localities  in  Shasta  County,  Calif. . . .  790 

280.  Section  of  Brown's  chromic  iron  ore  mine,  Shasta  County,  Calif.  .  .  .  791 

281.  Map  of  Cobalt-Porcupine-Sudbury  region 797 

282.  Geologic  map  of  Sudbury,  Ont.,  nickel  district 798 

283.  Geologic  section  of  Sudbury,  Ont.,  nickel  district.  . 798 

284.  Generalized  section  through  productive  part  of  Cobalt,  Ont.,  area.  .  801 

285.  Section  of  calcite,  and  native  silver,  Cobalt,  Ont 802 

286.  Approximate    quantitative    distribution    of    the    more    important 

minerals  associated  with  cassiterite 812 

287.  Diagram  to  illustrate  the  genetic  distribution  and  gradation  of  some 

of  the  more  common  minerals  in  their  association  with  cassiterite 
only 814 

288.  Sketch  map  showing  location  of  Carolina  tin  belt 815 

289.  Geologic  map  of  Altenberg-Zinnwald  tin  district,  Saxony 816 

290.  Map  showing  location  and  relations  of  rutile  deposits  in  Nelson 

County,  Va 820 

291.  Plans  and  section  in  General  Electric  Company's  mine,   Nelson 

County,  Va , .821 


LIST  OF  PLATES 


PLATE          FIO.  PAGE 

I.     1.  Subbituminous  coal > 3 

2.  Bituminous  coal 3 

II.     1.  Enlarged  section  of  bituminous  coal  from  Ohio 7 

2.  Enlarged  section  of  cannel  coal  from  Kentucky 7 

III.  1.  Subbituminous    coal    from    Marshall,    Colo.,   showing 

structure 11 

2.  Mineral  charcoal 11 

IV.  Map  showing  coal  fields  of  United  States  (colored) 25 

V.          Map  of  Pennsylvania,  showing  distribution  of  coals  by  fuel 

ratios 27 

VI.     1.  Pit  working  near  Milnesville,  Pa 33 

2.  View  in  Arkansas  coal  field 33 

VII.          Geologic  section  from  Kansas  City  to  Topeka,  Kas 39 

VIII.     1.  View  in  Subbituminous  coal  area,  between  Minera  and 

Cannel,  Texas . . 43 

2.  Lignite  seam,  Williston,  N.  Dak 43 

IX.     1.  Beds  of  Subbituminous  coal  near  Estevan,  Sask 51 

2.  Coke  ovens  and  tipple  at  Coleman,  Alberta. 51 

X.          Map  showing  areas  in  United  States  in  which  oil  and  gas 

are  known  to  occur 93 

XL     1.  Generalized  section  in  Appalachian  oil  field,  along  line 

ABof  Fig.  33 94 

2.  Northwest-southeast  section  in  Pennsylvania  oil  field 

along  line  CD  of  Fig.  33 94 

XII.     1.  General  view  of  Tuna  Valley  in  Pennsylvania  oil  field ....  101 

2.  View  in  Los  Angeles,  Cal.,  oil  field 101 

XIII.  General  view  of  Spindle  Top  oil  field,  Beaumont,  Tex 105  ' 

XIV.  General  view  of  Trinidad  asphalt  lake 119 

XV.     1.  View  of  portion  of  Trinidad  asphalt  lake,  showing  digging 

operations 123 

2.  Quarry  of  bituminous  sandstone,  Santa  Cruz,  Calif 123 

XVI.     1.  Granite  quarry,  Hardwick,  Vt 145 

2.  Quarry  in  volcanic  tuff,  north  of  Phoenix,  Ariz 145 

XVII.          Quarry  in  limestone,  Bedford,  Ind 151 

XVIII.          Marble  quarry,  Proctor,  Vt 155 

XIX.     1.  Marble  quarry,  Pickens  County,  Ga 157 

2.  Slate  quarry  at  Penrhyn,  Pa 157 

XX.          Green  slate  quarry,  Pawlet,  Vt 163 

XXL     1.  Kaolin  deposit  in  North  Carolina 177 

2.  Bank  of  sedimentary  fire  clays,  Woodbridge,  N.  J 177 

» 


XVI 


LIST    OF    PLATES 


FIG. 

1.  Quarry  of  natural  cement  rock,  Cumberland,  Md 195 

2.  Natural  cement  rock  quarry,  Milwaukee,  Wis 195 

XXIII.  1.  Limestone  quarry  in  Lehigh  cement  district,  Pa 203 

2.  Bog  lime  pit  at  Warners,  N.  Y 203 

XXIV.  1.  Interior  view  of  salt  mine,  Livonia,  N.  Y 219 

2.  Borax  mine,  near  Daggett,  Calif 219 

XXV.     1.  View  in  a  Nova  Scotia  gypsum  quarry,  showing  large 

mass  of  anhydrite 245 

2.  Gypsum  quarry,  Linden,  N.  Y 245 

XXVI.     1.  Gypsum  quarry,  Alabaster,  Mich 251 

2.  View  in  scythestohe  quarry,  Pike  Station,  N.  H 251 

XXVII.     1.  Rock  phosphate  mine  near  Ocala,  Fla 265 

2.  Phosphate  beds,  Montpelier,  Ido 265 

XXVIII.     1.  View  in  Tennessee,  brown  phosphate  deposit,  showing 

cutters  across  strike  of  trench 269 

2.  Collar  deposit  of  brown  phosphate  around  base  of  hill ....   269 

XXIX.     1.  Grindstone  quarry,  Tippecanoe,  0 285 

2.  Corundum  veir    between  peridotite  and  gneiss,  Corun- 
dum Hill,  Ga 285 

XXX.         View  in  Arkansas  novaculite  quarry 289 

XXXI.          General  view  of  Asbestos  quarry,  Thetford  Mines,  Quebec  303 
XXXII.     1.  Granite  Jike  cutting  peridotite  near  asbestos  veins,  Thet- 
ford, Que 305 

2.  Richardson  feldspar  mine  near  Godfrey,  Ont 305 

XXXIII.  1.  Stewart  graphite  mine,  near  Buckingham,  Que 325 

2.  Lacey  mica  mine,  Ontario 325 

XXXIV.  Map  of  portion  of  Kentucky  fluorite  district 331 

XXXV.     1.  Magnesite  mine  near  Winchester,  Calif 357 

2.  Network  of  magnesite  veins  in  serpentine,  same  irine .  .  .  .   357 

XXXVI.     1.  View  in  glass-sand  pit,  on  Severn  River,  Md 361 

2.  View  showing  sapphire  workings,  Yogo  Gulch,  Mont.  .  .  .   361 
XXXVII.     1.  Section  of  an  artesian  basin 415 

2.  Section  illustrating  conditions  of  flow  in  jointed  crystal- 

line rocks 415 

3.  Section  illustrating  conditions  of  flow  from  solution  pas- 

sages in  limestone 415 

4.  Section  illustrating  conditions  of  flow  from  fissures  in 

stratified  rocks  overlain  by  drift 415 

XXXVIII.     1.  Section  illustrating  conditions  of  flow  from  foliation  and 

schistosity  planes 419 

2.  Section  illustrating  conditions  of  flow  from  vesicular  trap  419 

3.  Section  showing  accumulation  of  water  in  stratified  rocks 

with  low  intake 419 

XXXIX.     1.  Specimen  showing  crustified  structure 439 

2.  Steamboat  Springs,  Nev 439 

XL.     1.  Banded  vein  from  Clausthal,  Ger 467 

2.  Banded  vein,  Clausthal,  Ger.,  showing  wall  rock 467 

XLI.     1.  Vein  specimen  from  Przibram,  Bohemia 469 

2.  Tin  veinlets  in  granite,  Altenberg,  Saxony 469 


LIST    OF   PLATES 


xvii 


PLATE  FIG.  PAGE 

XLII.          Polished  ore  specimens  from  Burro  Mountains,  N.  Mex., 

showing  replacement  of  pyrite  by  chalcocite 483 

XLIII.     1.  View  of  open  cut  in  magnetite,  Mineville,  N.  Y 509 

2.  General  view  of  magnetic  separating  plants  and  shaft 

houses,  Mineville,  N.  Y 509 

XLIV.     1.  View  of  iron  mines  at  Kiruna,  Sweden 519 

2.  View  of  iron  mine  at  Gellivare,  Sweden 519 

XLV.          General  view  of  Mountain  Iron  Mine,  Mesabi  Range, 

Minn 531 

XL VI.     1.  Iron  mine,  Soudan,  Minn 533 

2.  View  of  limonite  pit  near  Ironton,  Pa 533 

XLVIL          Geologic  map  of  western  half  of  Birmingham,Ala.,  district  538 
XLVIII.          Geologic  map  of  eastern  half  of  Birmingham,  Ala.,  district  539 

XLIX.     1.  Pit  of  residual  limonite,  Shelby,  Ala 551 

2.  Old  limonite  pit,  Ivanhoe,  Va.,  showing  pinnacled  surface 

of  limestone  which  underlies  ore-bearing  clay 551 

L.          Map  showing  distribution  of  copper  ores  in  the  U.  S 571 

LI.          Utah  Copper  Company's  mine,  Bingham,  Utah 581 

LII.     1.  Smelter  of  Arizona  Copper  Company,  Clifton,  Ariz 583 

2.  View  of  Bingham  Canon,  Utah 583 

LIII.     1.  View  looking  northeast  from  Eureka  ore  pit  of  the  Nevada 
Consolidated  Copper  Company,  Ruth,  Ely  District, 

Nevada 587 

2.  South  end  of  Eureka  ore  pit,  Ruth,  Nev. . .  , 587 

LIV.     1.  View  from  Old  Dominion  open  cut,  Globe,  Ariz.,  looking 

towards  Miami 589 

2.  Open  cut,  Mother  Lode  Mine,  near  Greenwood,  B.  C. .  .   589 

LV.          View  of  Anaconda  group  of  mines,  Butte,  Mont 597 

LVI.          View  from  Houghton,  Mich.,  looking  towards  Hancock.   607 
LVII.          Geologic  map  of  Franklin  Furnace,  N.  J.,  and  vicinity.  .  .    625 
LVIII.     1.  View  from  Carbonate  Hill,  Leadville,  towards  Iron  Hill .  .   634 
2.  View  from  Carbonate  Hill,  overlooking  California  Gulch 

and  Leadville 634 

LIX.     1.  View  of  valley  at  Austinville,  Va 637 

2.  Old  oxidized  ore  workings  at  Austinville,  Va 637 

LX.     1.  View  in  Joplin  district  near  Webb  City,  Mo 643 

2.  Workings  in  Disbrow  mine,  near  Webb  City,  Mo 643 

LXI.     1.  View  near  Linden,  Wisconsin,  zinc  mines 661 

2.  View  looking  north  over  Coeur  d'Alene  Mountains 661 

LXII.     1    General  view  of  Rico,  Colo 667 

2.  View  of  a  portion  of  Mercur,  Utah 667 

LXIII.     1.  Mill  of  Nickel  Plate  mine,  Hedley,  B.  C 687 

2.  Virginia  City,  Nev 687 

LXIV.          Homestead  Mills,  hoists,  and  open  cuts  at  Lead,  S.  Dak. .   689 
LXV.     1.  Kennedy  mine  on  the  Mother  Lode,  near  Jackson,  Calif. .   697 
2.  Auriferous  quartz  veins  in  Maryland  mine,  Nevada  City, 

Calif 697 

LXVI.          Vertical  and  horizontal  plan  of  Kelly  tunnel  and  associ- 
ated mine  workings,  Georgetown,  Col 699 


XV111 


LIST   OF   PLATES 


PLATE  FH3.  PAGE 

LXVII           Plans  of  the  principal  levels  of  the  January  mine,  Gold- 
field,  Nev 711 

LXVIII.     1.  Columbia  Mountain,  Goldfield,  Nev 713 

2.  Ledge  outcrop  in  dacite  between  the  Blue  Bell  and 

Commonwealth  mines,  Goldfield,  Nev 713 

LXIX.          General  view  in  Cripple  Creek  district 717 

LXX.     1.  View    of    Independence    Mine    and    Battle    Mountain, 

Cripple  Creek,  Col 723 

2.  General  view  of  region  around  Tonopah,  Nev 723 

LXXI  General  columnar  section  of  A,  Ouray  quadrangle;  B, 

Telluride  quadrangle 725 

LXXII      1 .  Hydraulic  mining  of  auriferous  gravel 733 

2.  An  Alaskan  placer  deposit 733 

LXXIII.          Crimora  manganese  mine,  Virginia 763 

LXXIV.     1.  View  of  bauxite  bank,  Rock  Run,  Ala 765 

2.  Furnace  for  roasting  Mercury  ore,  Terlingua,  Tex 765 

LXXV.     1.  Old  workings  of  tin  mine,  Altenberg,  Saxony 817 

2.  Rutile  mine,  near  Roseland,  Va 817 


CHAPTER  I 


COAL 

Kinds  of  Coal.  —  There  is  such  an  intimate  gradation  between 
vegetable  accumulation  now  in  process  of  formation  and  mineral 
coal  that  it  is  generally  admitted  that  coal  is  of  vegetable  origin. 
By  a  series  of  slow  changes  (p.  17)  the  vegetable  remains  lose 
water  and  gases,  the  carbon  becomes  concentrated,  and  the  ma- 
terials assume  the  appearance  of  coal.  To  the  several  stages 
of  this  process  the  following  names  are  given:  peat,  lignite,  sub- 
bituminous,  bituminous,  semibituminous,  semianthracite,  and 
anthracite. 

Peat  (119-130.)  —  This,  which  represents  the  first  stage  in  coal 
formation,  is  formed  by  the  growth  and  decay  of  grasses,  sphagnum, 
and  other  plants  in  moist  places.  A  section  in  a  peat  bog  from  the 
top  downward  may  show:  (1)  A  layer  of  living  plants;  (2)  a  layer 
of  dead  plant  fibers,  whose  structure  is  clearly  recognizable  and 
which  grades  into  (3)  a  layer  of  fully  formed  peat,  a  dense,  brownish 
black  mass,  of  more  or  less  jellylike  character,  in  which  the  vege- 
table structure  is  often  indistinct. 

The  following  analyses  show  the  difference  in  composition  of  the 
different  layers.1  They  also  show  that  while  during  this  change 
the  hydrogen  and  oxygen  diminish,  the  carbon  increases  in  propor- 
tion. 

ANALYSES  OF  DIFFERENT  LAYERS  OF  A  PEAT  BOG 


MATERIAL 

CAUBON 

HYDROGEN 

OXYGEN 

NITROGEN 

Sphagnum      .                                   . 

49.88 
50.86 
53.51 
56.43 
59  7 

6.54 
5.8 
5.9 
5.32 
5.7 

42.42 
42.57 
40. 
38. 
33.04 

1.16 
.77 
59 
25 
1.56 

Porous,  light  brown  sphagnum  peat 
Porous,  red-brown  peat  .          ... 

Heavy  brown  peat      
Heavy  black  peat 

1  The  fact  that  sphagnum  occurs  on  the  surface  is  not  necessarily  an  indication 
that  it  was  the  only  peat-forming  plant  present. 
B  1 


2  ECONOMIC  GEOLOGY 

Lignite.  —  This  substance,  also  called  brown  coal,  represent- 
ing the  second  stage  in  coal  formation,  is  usually  brown  or 
sometimes  yellowish  in  color,  woody  in  texture,  and  has  a  brown 
streak.  It  burns  readily,  but  with  a  long  smoky  flame,  and 
with  lower  heating  power  than  the  higher  grades  of  coal.  Be- 
cause of  the  large  amount  of  moisture  it  often  dries  out  on 
exposure  to  the  air,  and  rapidly  disintegrates  to  a  powdery  mass. 

Lignite  is  distantly  jointed,  and  as  mined  is  as  a  rule  irregu- 
larly slabby. 

The  lignites  are  usually  restricted  to  the  younger  formations. 
They  are  found  in  the  various  stages  of  the  Cretaceous  and  Terti- 
ary of  the  United  States  and  Canada.  Exceptionally  they  occur 
in  beds  as  old  as  the  Carboniferous,  as  in  Russia  (lla,  p.  65). 

Jet  is  a  coal-black  variety  of  lignite,  with  resinous  luster  and  sufficient 
density  to  permit  its  being  carved  into  small  ornaments.  It  is  obtained  on 
the  Yorkshire  coast  of  England,  where  a  single  seam  produced  5180  pounds, 
valued  at  $1250.  According  to  Phillips,  jet  is  simply  a  coniferous  wood, 
still  showing  the  characteristic  structure  under  the  microscope.  (''Geology 
of  England  and  Wales,"  p.  278.) 

Subbitumincus  Coal  cr  Black  Lignite.  —  A  grade  intermediate 
between  lignite  and  bituminous,  and  sometimes  difficultly  dis- 
tinguishable from  these.  It  is  usually  glossy  black,  and  rela- 
tively free  from  joints.  T  he  moisture  content  is  commonly  over  10 
per  cent  and  the  calorific  value  from  8000  to  10,000  British  thermal 
units  (I2a).  Campbell  (is)  has  pointed  out  that  it  checks  irregu- 
larly on  drying  and  when  weathered  splits  parallel  with  the  bed- 
ding, while  bituminous  coal  shows  a  columnar  cleavage  (Plate  I). 

Bituminous  Coal.  • —  This  represents  the  fourth  stage  in  coal 
formation.  It  is  denser  than  the  lignites,  deep  black,  compara- 
tively brittle,  and  breaks  with  cubical  or  sometimes  conchoidal 
fracture.  On  superficial  inspection  it  shows  imperfect  traces  of 
vegetable  remains  (Hate  III);  but  in  thin  sections  examined 
under  the  microscope,  traces  of  woody  fiber,  lycopod  spores,  etc., 
are  commonly  seen  (Plate  II).  Bituminous  coal  burns  readily, 
with  a  smoky  flame  of  yellow  color,  but  with  greater  heating 
power  than  lignite.  It  does  not  disintegrate  on  exposure  to 
a  r  as  readily  as  lignite  does.  Most  bituminous  coal  is  of  earlier 
age  than  lignite;  but  where  the  two  occur  in  the  same  forma- 
tion, as  in  parts  of  the  West,  the  lignite  is  commonly  in  hori- 
zontal strata,  while  the  bituminous  coal  occurs  in  areas  of  at 
least  slight  disturbance. 


PLATE  I 


mmm 


FIG.  1.  —  Subbituminous  Coal,  showing  the  irregular  checking  developed  in  drying. 
(After  Campbell,  Econ.  GeoL,  III.) 


FIG.  2.  —  Bituminous  Coal,  showing  prismatic  structure.     (After  Campbell.) 

(3) 


4  ECONOMIC  GEOLOGY 

When  freed  of  their  volatile  hydrocarbons  and  other  gaseous  constituents 
by  heating  to  redness  in  a  coke  oven,  many  bituminous  coals  cake  to  a  hard 
mass  called  coke.  Since  all  bituminous  coals  do  not  possess  this  charac- 
teristic, it  is  customary  to  divide  these  coals  into  coking  and  non-coking 
coals. 

The  cause  of  coking  is  not  clearly  understood,  and  the  chemical  anal- 
ysis does  not  appear  to  throw  much  light  on  the  matter.  It  has  been 
suggested  that  the  quality  of  coking  may  be  influenced  by  the  character  of 
the  plant  remains  making  up  the  coal.  A  proper  determination  of  the  coking 
qualities  of  a  coal  usually  involves  a  practical  test,  but  it  seems  that  the 
coking  qualities  of  a  coal  may  be  inferred  with  fair  accuracy  by  its  behavior 
when  ground  in  an  agate  mortar.  Coals  of  good  coking  character  stick  to 
the  mortar,  while  those  of  opposite  quality  are  easily  brushed  loose  (28). 

The  coking  value  of  a  coal  (20)  seems  to  be  indicated  with  fair  accuracy 
by  the  hydrogen-oxygen  ratio,  calculated  on  a  moisture-free  basis.  Prac- 

TT 

tically  all  coals  with  —  >58  per  cent  seem  to  possess  coking  qualities.     Most 

TT 

coals  with  —  down  to  55  make  coke  of  some  kind,   and  a  few  with  ratios 

as  low  as  50  will  coke,  though  the  product  is  rarely  good. 

The  hydrogen-oxygen  ratio  may  fail  as  a  guide  in  those  coals  under- 
going anthracitization. 

The  formation  of  coke  by  natural  processes  is  referred  to  on  p.  5. 

Cannel  Coal.  —  This  is  a  compact  variety  of  non-coking  bitu- 
minous coal,  with  a  dull  luster  and  conchoid al  fracture.  Owing 
to  its  unusually  high  percentage  of  volatile  hydrocarbons,  upon 
which  its  chief  value  depends,  cannel  coal  ignites  easily,  burning 
with  a  yellow  flame,  and  when  heated  tends  to  decrepitate. 
Microscopic  examination  of  thin  sections  shows  that  it  consists 
largely  of  spores  (4a,  12a) . 

Semibituminous  Coal.  —  This  term  was  proposed  by  H.  D. 
Rogers  as  early  as  1858  1  to  apply  to  those  grades  above  bitumi- 
nous, whose  volatile  matters  were  between  12  and  18  per  cent; 
while  Frazer,  in  1879 ,2  used  it  to  include  those  coals  whose  "fuel 
ratios  "  (p.  19)  ranged  from  8  to  5. 

Semianthracite  Coal.  —  This  term  was  employed  by  Rogers 
at  the  same  time,  and  included  those  coals  between  bituminous 
and  anthracite  having  less  than  10  per  cent  volatile  matter. 
Frazer  later  included  under  it  those  coals  whose  fuel-ratios 
ranged  from  12  to  8. 

Both  terms  persist,  perhaps  unfortunately,  to  the  present 
day,  and  are  sometimes  no  doubt  rather  loosely  used.  Possibly 

1  Geology  of  Pennsylvania,  II:   983. 

*  Second  Pennsylvania  Geological  Survey,  Rept.  MM:   148,  1879. 


COAL  5 

the  disagreement  among  different  people  as  to  what  shall  be 
included  under  these  terms  may  be  partly  responsible  for  the 
confusion. 

Anthracite  Coal.  —  This  coal  is  black,  hard,  and  brittle,  with 
high  luster  and  conchoidal  fracture.  It  represents  the  last  stage 
in  the  formation  of  coal,  and  like  bituminous  coal,  may  show 
jet-like  bands,  representing  flattened  stems  or  trunks.  Anthra- 
cite has  a  lower  percentage  of  volatile  hydrocarbons  and  higher 
percentage  of  fixed  carbons  than  any  of  the  other  varieties.  On 
this  account,  it  ignites  much  less  easily  and  burns  with  a  short 
flame,  but  gives  great  heat. 

The  geological  distribution  of  anthracite  is  more  restricted 
than  that  of  bituminous  coal,  and  in  fact  its  occurrence  is  often 
more  or  less  intimately  connected  with  dynamic  disturbances. 

Carbonite  or  Natural  Coke.  —  This  term  is  applied  to  natural 
coke,  which  is  formed  by  igneous  rocks  cutting  across  bituminous 
coal  seams.  As  illustrative  may  be  mentioned  an  occurrence  in 
central  Utah,1  where  "  dikes  of  igneous  rocks  ten  feet  in  width  have 
cut  vertically  across  the  coal  bed,  nine  to  sixteen  feet  thick,  meta- 
morphosing the  coal  into  a  coke-like  substance  to  a  distance  of  three 
feet  on  either  side.  The  coal  thus  fused  is  distinctly  columnar,  the 
columns  standing  perpendicular  to  the  face  of  the  dike;  it  has  a 
graphitic  luster,  but  is  not  vesicular  like  artificial  coke."  Natural 
coke  is  also  found  in  New  Mexico,  Colorado,  and  Virginia. 

The  higher  quantity  of  volatile  matter  in  carbonite  than  arti- 
ficial coke  may  be  due  to  its  having  formed  at  some  depth  below  the 
surface,  thus  preventing  the  escape  of  the  volatile  matter,  short 
heating,  or  enrichment  by  gases  from  the  neighboring  coal. 

ANALYSES  OF  NATURAL  COKE 


I 

II 

III 

Moisture     

1  116 

32 

4.55 

Volatile  hydrocarbons  .... 
Fixed  carbon 

11.977 
75  081 

20.38 
65  90 

4.43 

84.67 

Ash   .     . 

11  826 

13  10 

6  35 

I.  Richmond,  Va.,  coal  basin.  —  Watson,  Min.  Res.  of  Va.,  p.  343,  1907. 
II.  Book  Cliffs  coal  field,  Utah.  —  Taff,  Science,  N.S.  XXIII  :  696, 
1906.  III.  Cerrillos  Hills  district,  N.M.  —  Johnson,  Sch.  of  M. 
Quart.,  XXIV:  492,  1903. 


iTaff,  Science,  N.  S.,  XXIII:    696,  1906. 


6  ECONOMIC  GEOLOGY 

Proximate  Analysis  of  Coal.  —  An  elementary  analysis  of  coal 
(see  p.  18)  is  of  comparatiyely  little  practical  value.  Therefore 
proximate  analyses 'are  commonly  employed,  in  which  the  prob- 
able method  of  combination  of  the  elements  is  given.  By  the 
proximate  method  the  elements  in  the  coal  are  grouped  as 
moisture,  volatile  matter,  fixed  carbon,  ash,  and  sulphur.1 

The  moisture  can  be  driven  off  at  100°  C.  and  is  usually  highest  in  peat 
and  lignite.  The  volatile  matter  was  formerly  termed  volatile  hydro- 
carbons, but  it  is  now  clear  that  other  substances  also  are  driven  off  at  a 
red  heat,  and  that  the  volatile  matter  of  coals  differs  greatly  in  its  char- 
acter.2 

The  coals  of  the  younger  geological  formations  of  the  West  have  a  large 
proportion  of  carbon  dioxide,  carbon  monoxide  and  water,  and  a  corre- 
spondingly small  proportion  of  hydrocarbons  and  tarry  vapors.  The  Appa- 
lachian coals,  on  the  other  hand,  contain  much  tarry  vapor  and  hydro- 
carbon compounds. 

The  ash  represents  noncombustible  mineral  matter  and  bears  no  direct 
relation  to  the  kind  of  coal;  and  the  same  is  true  of  sulphur,  which  is  present 
as  an  ingredient  of  pyrite  or  gypsum. 

The  value  of  coal  for  fuel  or  other  purposes  is  determined  mainly  by  the 
relative  amounts  of  its  fuel  constituents,  viz.,  the  volatile  hydrocarbons 
and  the  nonvolatile  or  fixed  carbons.  The  fuel  value,  or  fuel  ratio,  is  de- 
termined by  dividing  the  fixed  carbon  percentage  by  that  of  the  volatile 
hydrocarbons. 

The  fixed  carbon  of  the  coal  burns  with  difficulty  and  is  highest  in  the 
anthracite  variety.  The  value  of  a  coal  for  fuel  purposes  is  determined 
mainly  by  the  relative  amounts  of  its  different  constituents.  Thus  both 
the  fixed  carbon  and  volatile  hydrocarbons  represent  heating  elements 
in  tfie  coal,  the  forrrer  being  the  stronger.  The  maximum  calorific  value 
seems  to  be  reached  when  the  volatile  combustible  matter  is  about  18  per 
cent  of  the  total  combustible. 

Coals  with  a  high  percentage  of  fixed  carbon  develop  great  heating 
power,  while  those  lower  in  fixed  carbon  and  high  in  volatile  hydrocarbons 
lack  in  heating  power,  but  are  free  burning. 

Moisture  is  a  nonessential  constituent  of  coal.  It  not  only  displaces 
so  much  combustible  matter,  but  requires  heat  for  its  evaporation.  When 
present  in  large  amounts  it  often  causes  the  coal  to  disintegrate  while 
drying  out.  It  ranges  from  perhaps  2  or  3  per  cent  in  anthracite  to  20  or 
30  per  cent  in  lignites. 

Ash  also  displaces  combustible  matter,  but  otherwise  it  is  in  most  cases 
an  inert  impurity.  The  clinkering  of  coal  is  commonly  due  to  a  high  per- 
centage of  fusible  impurities  in  the  ash,  and  for  metallurgical  work  the 
composition  of  the  ash  often  has  to  be  considered. 

1  The  proximate  analysis,  though  apparently  a  simple  operation,  needs  to  be 
carefully  carried  out  to  prevent  variable  results.     See  in  this  connection  U.  S.  Geol. 
Surv.,  Prof.  Pap.  48,  I,  and  Bur.  Mines,  Tech.  Pap.  8,  1913. 

2  Bur.  Mines,  Bull.  1,  1910. 


PLATE  II 


FIG.  1.  —  Enlarged  section  of  bituminous  coal  from  Ohio.  Crenulated  bands  are 
modified  lignitic  material.  Dark  bands  canneloid.  White  bodies,  flattened 
spores.  (E.  C.  Jeffrey,  photo.} 


FIG.  2.  —  Enlarged   section   of    cannel    coal   from    Kentucky.     Light  undulating 
bands,  wood.     White  bodies,  flattened  spores.     (E.  C.  Jeffrey,  photo.) 

(7) 


ECONOMIC   GEOLOGY 

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ECONOMIC   GEOLOGY 


The  following  analyses  will  also  serve   to  illustrate  the  composition  of 
the  ash: — 

ASH  ANALYSES 


Si02 

AhOs 

Fe203 

CaO 

MgO 

MnO2 

SOs 

Na2O 
K2O 

Cl 

P205 

Peat,  average  of 

• 

OK     CA 

578 

10   70 

94.  r\o 

390 

7    "iO 

1  72 

60 

9    ^f\ 

Lignite 

30.14 

13.48 

11.70 

23.59 

.88 

3.32 

14.22 

Bituminous  coal 

34.32 

14.62 

22.94 

14.85 

1.42 

1.16 

10.97 

Sulphur  is  an  objectionable  impurity  in  steaming  coals  on  account  of  its 
corrosive  action  on  the  boiler  tubes.  It  is  also  undesirable  in  coals  to  be 
used  for  metallurgical  purposes  and  gas  manufacture. 

The  table  on  page  9  gives  the  proximate  and  ultimate  analyses  of  a  number 
of  coals  from  different  parts  of  the  United  States  and  Canada,  the  analyses 
being  arranged  according  to  grades.1 

Origin  of  Coal  (l-l2a). —  It  has  been  shown  that  there  are 
gradations  between  unquestioned  plant  beds  and  mineral  coal, 
and  that  coal,  besides  containing  the  same  elements  as  plant 
tissues,  although  in  different  proportions,  often  shows  the  pres- 
ence of  plant  fibers,  leaves,  steins,  seeds,  etc.,  in  addition  to 
their  occurrence  in  the  associated  rocks.  Moreover,  stumps  of 
trunks  of  trees  are  sometimes  found  standing  upright  in  the 
coal,  with  their  roots  penetrating  the  underlying  bed  of  clay 
(6,  9),  just  as  trunks  of  trees  at  present  stand  in  bogs.  While 
these  facts  point  unmistakably  to  a  vegetable  origin  of  coal,  it 
is  less  easy  to  understand  the  exact  manner  in  which  the  great 
accumulations  of  vegetable  matter  have  been  made,  and  the 
changes  from  plant  tissue  to  mineral  coal.  The  several  points 
requiring  explanation  therefore  are:  (a)  conditions  of  accumu- 
lation", (b)  character  of  organisms  forming  coal,  (c)  conditions 
of  initial  process  of  organic  decomposition,  and  (d)  nature  of 
forces  bringing  about  subsequent  alteration  of  organic  residues. 

Conditions  of  Vegetable  Accumulation  (4a,  5,  9,  12,  12a).  —  While 
it  is  generally  agreed  that  coal  originated  by  the  accumu- 
lation and  slow  decay  of  vegetable  matter  under  water,  a  dif- 
ference of  opinion  may  exist  as  to  whether  the  vegetable  matter 
accumulated  by  growth  in  place  (autochthonous  origin)  or  by  the 

i  The  type  names  are  in  each  case  those  given  in  the  reports  from  which  analyses 
were  taken. 


PLATE  III 


j 


FIG.  1. — Subbituminous  Coal  from  Marshall,  Colo. 

a.  Jet-black  Lenses  represent  Stems  Flattened  by  Pressure. 
Dull  layers,  composed  of  Decayed  Wood,  Cuticles,  Leaf  Laminae,  etc. 


FIG.  2.—"  Mineral  Charcoal."     (AJter  White  and  Thiessen,  Bur.  Mines,  Bull.  38.) 


12  ECONOMIC  GEOLOGY 

accumulation  of  transported  vegetable  matter  (allochthonous 
origin] . 

As  favoring  the  former  theory  we  have  the  perfect  preserva- 
tion of  many  plant  remains,  a  condition  unlikely  to  exist  if  the 
material  had  been  transported  by  streams,  and  the  upright 
trunks  in  coal,  with  roots  extending  into  the  under  clay,  the 
latter  supposedly  representing  the  old  soils  or  bottom  muds 
of  the  swamps  in  which  the  coal-forming  plants  grew. 

It  is  true,  however,  that  allochthonous  coals  may  exist,  be- 
cause some  formations  have  local  coal  deposits  occurring  as 
thin  wedges  or  lenses,  derived  from  drifting  plant  material, 
with  no  roots  penetrating  the  under  clay.  Indeed,  some  recent 
writers,  among  them  Jeffrey  in  the  United  States  (4a,  246), 
have  argued  most  strongly  in  favor  of  this  view,  because  of 
the  high  spore  content  of  many  coals,  which  could  only  be  due 
to  accumulation  in  open  water.  The  process  is  a  slow  one, 
but  its  analogue  is  to  be  seen  in  modern  lakes. 

Possibly  also  some  deposits  represent  vegetable  accumula- 
tions in  delta  deposits,  or  in  lacustrine  beds,  as  in  the  case  of 
the  Commentry  fresh-water  basin  of  France  1  or  the  Tertiary 
coals  of  the  Frazer  delta  in  British  Columbia. 

A  difficulty  to  be  overcome  is  the  fact  that  while  peat  bogs 
are  known  covering  several  square  miles  of  area,  they  are  not 
comparable  in  size  to  the  extensive  coal  deposits  found  in  .many 
parts  of  the  world. 

Perhaps  the  most  perfect  resemblance  to  coal-forming  con- 
ditions is  that  now  found  in  the  Dismal  Swamp  of  Virginia  and 
North  Carolina,  or  the  Great  Sumatra  Swamp.2 

In  the  former  the  area  is  very  level,  though  with  slight  de- 
pressions in  which  there  is  either  standing  water  or  swamp  con- 
ditions. Indeed,  there  is  "such  a  general  interference  with  free 
drainage  that  the  swamp  areas  are  extensive,  and  vegetable 
accumulations  are  taking  place,  a  thickness  of  8-12  feet  of  peat 
having  formed.  There  is,  moreover,  a  general  absence  of  sed- 
iment. 

In  the  latter  swamp,  which  covers  more  than  80,000  hectares 
(308.8  square  miles)  there  is  being  deposited  a  high-grade  peat 
reaching  a  depth  of  9  meters,  and  having  only  6.39  per  cent  ash 
in  the  dry  fuel. 

1  Stevenson,  Ann.,  N.  Y.  Acad.  Sci.,  XIX:   161,  1910. 
.  *  Potonie,  Entstehung  der  Bteinkohle,  5th  Ed.:    154,  1910. 


COAL  13 

If  either  of  these  areas  were  submerged  beneath  the  sea,  the, 
vegetable  remains  would  be  buried  and  a  further  step  made 
toward  the  formation  of  a  coal  bed.  Re-elevation,  making  a 
coastal  plain,  would  permit  the  accumulation  of  another  coal- 
bed  above  the  first,  and  this  process  might  be  continued  again 
and  again. 

The  evidence  now  at  hand  indicates  that  the  vast  deposits    ,;; 
of  peat  which  represent  the  first  stage  in  coal  formations  were 
probably  accumulated  near  tide  level  for  the  following  reasons: 
(1)  Marine  beds  are   often  intercalated   in   the   coal   measures, 
and  are  sometimes  found  overlying  the  coal;    (2)  brackish-water    , 
molluscs  are  found  in  some  of  the  rocks  of  the  coal  basins;    (3) 
the  coal  strata  show  a  marked  parallelism  and  a  frequency  of 
salt-water  invasion. 

The  coal-forming  plants  were  of  fresh-water  character,  and 
the  ingress  of  the  sea  was  probably  prevented  either  by  the 
presence  of  barrier  ridges  which  kept  out  the  salt  water,  or  in 
other  cases  a  thick  plant  growth  around  the  borders  of  the 
swamps  may  have  prevented  any  serious  inflow  of  salt  water. 

The  presumption  is,  then,  that  in  many  cases  the  coal-forming 
plants  grew  in  coastal  or  lacustrine  swamps  developed  in  regions 
of  slight  submergence  of  a  very  mature  and  broadly  extended 
peneplain.1 

Some  peat  swamps  were  probably  located  in  vast  deltas, 
but  it  is  doubtful  if  such  large  vegetable  accumulations  took 
place  in  salt  water,  for  although  peat  is  known  to  be  in  process 
of  formation  in  salt  marshes,  White  (I2a)  says,  "  it  does  not  seem 
clear  that  coal  with  so  large  a  percentage  of  mother  of  coal, 
jet-like  wood,  etc.,  and  with  such  pure  carbonaceous  matter, 
that  is,  containing  such  a  moderate  percentage  of  ash,  as  the 
coal  in  the  Carboniferous  of  Illinois  -or  Indiana,  or  that  inter- 
bedded  with  marine  or  brackish  water  beds  in  Wyoming,  was 
laid  down  in  estuaries  flooded  by  sea  water." 

A  distinction  is,  however,  sometimes  made  between:    (1)  lim- 
netic coals,  or  those  derived  from  plant  remains  accumulated  in 
fresh  water;   and  (2)  paralic  coals,  or  those  derived  from  plant  jj 
remains  which  collected  in  marshes  near  the  sea  border. 

Character    of   Organisms    Forming  Coal   (4a,   12,   I2a,   246) .  — 

1  Schuchert  points  to  the  persistent  high  sulphur  content  of  the  Mississippi 
Valley  coals  as  significant,  for  he  states  that  this  element  is  always  present  in 
marine  marshes  and  almost  wanting  in  fresh-water  ones. 


14  ECONOMIC  GEOLOGY 

Microscopic  study  of  different  coals  shows  that  the  material  is 
composed  of  plant  residues,  consisting  of  the  most  resistant 
components  of  plants. 

The  three  important  recognizable  constituents  are  spores  or 
canneloid,  modified  wood  or  lignitoid,  and  to  a  less  extent  of 
relatively  unmodified  carbonized  wood  or  mineral  charcoal  (mother 
cf  coal)  (Plate  III,  Fig.  2).  There  may  also  be  resins,  and  resin 
waxes. 

Examination  of  lignites  by  White  (I2o)  showed  them  to  con- 
sist chiefly  of  woody  material,  the  interstices  being  filled  with 
debris  of  macerated  plant  refuse,  comparable  to  many  of  the 
corresponding  varieties  of  black  amorphous  peat,  and  composed 
of  the  more  resistant  residue  of  plant  parts,  such  as  woody 
fragments,  resinous  substances,  spore  and  pollen  eximes,  cuticles 
and  a  cellulosic  residue  forming  the  binding  substance. 

Subbituminous  coal  shows  greater  density  and  higher  con- 
centration of  resinous  and  cutinous  substances,  while  stems, 
trunks  or  branches  appear  as  layers  or  lenses  of  dark  black, 
or  jetty,  glassy  character,  and  characteristic  luster  (Plate  III, 
Fig.  1). 

These  same  jetty  layers  show  in  bituminous  coal  (Plate  III, 
Fig.  1),  while  the  dull  lamina?  between  represent  plant  debris. 

Cannel  coal  is  formed  almost  entirely  of  spore  eximes,  the 
resins  and  cuticles  forming  only  a  small  proportion  of  the  mass. 
These  spores  were  formerly  mistaken  by  some  for  algae,  and  it 
is  now  recognized  that  neither  the  latter  nor  any  homogeneous 
fundamental  jelly-like  substance  of  this  nature  is  present  in 
bog-head,  cannel,  or  any  other  coal. 

Conditions  of  Decomposition.  —  Two  stages  may  be  recognized 
in  the  coalification  process,  viz.,  (a)  the  putrefaction  stage,  which 
is  a  biochemical  process,  and  (b)  the  alteration  or  metamorphic 
stage,  involving  dynamo-chemical  action. 

When  dead  vegetable  matter  accumulates  under  water,  it 
does  not  remain  unchanged,  but  undergoes  a  deoxygenation  and 
dehydrogenation  process,  which  is  accomplished  by  fermentation 
or  maceration  in  which  minute  plants  (bacteria)  and  also  ani- 
mals take  part.  As  a  result  of  this  the  plant  tissues  break  down 
to  a  greater  or  less  degree,  depending  on  the  stage  of  decay. 
The  change  may  advance  no  further  than  to  convert  the  mass 
into  woody  or  fibrous  peat,  or  it  may  go  far  enough  to  obliterate 
most  of  the  plant  structures,  giving  a  somewhat  jelly-like  black 


COAL  15 

peat,  which  changes  into  the  so-called  amorphous  coal.  It  is 
highly  probable  that  the  process  of  decay  had  not  advanced  to 
the  same  stage  in  all  peats  prior  to  their  burial  under  sediment. 

The  decomposition  of  the  original  cellulose  (C&HioOs)  of  the 
plant  tissue  liberates  substances  such  as  CEU,  as  well  as  CO 2, 
CO,  H2O,  etc.  It  seems  probable  that  the  jellification  process 
leads  no  further  than  peat,  and  that  for  the  development  of 
the  later  stages  dynamo-chemical  changes  are  necessary. 

While  in  peat  beds  the  lower  layers  are  under  gentle  pres- 
sure, so  that  a  bed  1  foot  thick,  when  buried  under  15  or  20 
feet  of  other  peat  layers,  may  be  reduced  to  about  1  inch  in 
thickness,  the  real  consolidation  does  not  begin  until  it  is  buried 
under  a  greater  weight  of  sediment. 

Indeed,  heat  and  pressure  seem  necessary  for  the  change 
from  lignite  to  bituminous  coal,  and  long  periods  of  time  are 
apparently  required  for  the  slow  changes  that  take  place. 

The  process  of  change  from  lignite  on  is  to  be  regarded  as 
a  dynamo-chemical  one,  which  may  in  fact  overlap  the  bio- 
chemical changes. 

The  first  stage  in  the  densification  of  peat  under  load  is  of 
this  nature.  Occluded  gases  are  expelled,  liquid  putrefaction 
products  forming  the  cementing  paste  or  binder  of  the  coal 
are  partly  hardened,  and  a  reduction  of  the  mass  takes  place. 

As  the  change  continues,  there  is  a  progressive  de volatiliza- 
tion due  to  geodynamic  processes,  and  while  the  exact  changes 
and  compounds  evolved  are  not  known,  we  do  know  that  there 
is  a  reduction  of  the  volatile  combustible  matter. 

It  has  been  commonly  assumed  that  to  produce  the  higher  grades 
such  as  anthracite,  strong  folding  was  necessary,  in  order  to  develop 
sufficient  heat  and  pressure  for  this  degree  of  metamorphism.  M. 
R.  Campbell  (2, 10)  has,  however,  argued  with  apparent  reason  that 
while  the  chemical  changes  involved  are  induced  by  heat  (of  ordi- 
nary temperature),  still  these  changes  are  retarded  or  prevented 
unless  the  structural  conditions  (presence  of  joints,  etc.)  are 
favorable  for  the  escape  of  the  gaseous  products  of  this  change. 

Thus,  for  example,  the  Pennsylvania  anthracites  are  formed  not 
so  much  because  of  heat  and  pressure,  but  because  of  the  cracking  of 
the  rocks  which  allowed  thorough  oxidation.  The  same  amount 
of  folding  in  the  Pocono  rocks  of  Maryland  has  not  produced  any 
anthracite,  as  the  structural  conditions  were  not  favorable  for  the 
free  escape  of  the  gases. 


16  ECONOMIC,  GEOLOGY 

Cases  are  known,  where  the  heat  causing  the  changes  is  intense 
and  local,  as  in  the  Cerrillos  coal  field  of  New  Mexico  (80),  or  the 
Crested  Butte  district  of  Colorado  (5o),  where  bituminous  coal  has 
been  locally  changed  to  anthracite  by  a  near-by  igneous  intrusion. 

Some  geologists,  notably  J.  J.  Stevenson,  have  argued  that  the 
anthracite  coal  has  not  been  developed  from  bituminous  coal  by 
metamorphism,  but  that  the  volatile  constituents  were  partly 
removed  by  longer  exposure  of  the  vegetable  matter  to  oxidation 
before  burial  (11).  Among  paleobotanists  there  is  also  a  difference 
of  opinion  as  to  whether  the  succession,  peat,  lignite,  etc.,  is  a 
strictly  lineal  one. 

David  White  (I2a)  has  recently  again  called  attention  to  the 
thrust-pressure  hypothesis,  which  postulates  that  the  devola- 
tilization  of  coal  is  the  result  of  thrust  pressure. 

He  points  out  that  as  a  result  of  regional  thrust  pressure, 
essentially  horizontal  in  direction,  the  coal  has  become  dense, 
lithified,  jointed,  further  reduced  in  volume,  schistose  and  even 
crushed,  or  possibly  cemented,  while  gradually  becoming  pro- 
gressively dehydrated,  devolatilized,  and  concentrated  both  as 
to  volume  and  as  to  its  combustible  matter. 

This  pressure,  acting  on  and  transmitted  with  diminishing 
(progressively  compensated)  force  through  the  buried  and  loaded 
coal-bearing  strata,  has  converted  lignite  successively  into  sub- 
bituminous,  semibituminous,  semianthracite,  anthracite,  and 
even  into  graphitic  coal.  , 

The  degree  of  devolatilization  depends,  other  things  being 
equal,  on  the  intensity  and  the  duration  of  the  pressure  move- 
ment, a  long  moderate  pressure  being  as  effective  as  a  short 
intense  one. 

In  considering  the  evidence  bearing  on  this  hypothesis 
White  points  out  that  we  must  remember  that:  (1)  The  de- 
volatilization  of  coal  is  still  going  on  in  many  parts  of  the  world, 
the  rate  being  almost  insensible  in  some  districts,  but  clearly 
perceptible  in  others,  where  active  gas  production  is  observed 
in  certain  mines.  (2)  There  is  no  sharp  line  of  separation  between 
the  different  kinds  of  coal,  the  intergradation  being  complete 
between  peat,  lignite  and  semigraphitic  coal.  (3)  The  physical 
evidences  of  thrust  pressure,  such  as  jointing,  cleavage,  folding, 
faulting,  crushing,  etc.,  become  in  general  more  highly  developed 
and  conspicuous,  not  only  in  the  coal,  but  also  the  enclosing 
rocks,  as  the  alteration  of  the  coal  proceeds,  and  hence  regions 


COAL  17 

of  greater  change  in  the  coal  show  the  physical  effects  of  greater 
pressure. 

In  regions  of  initially  equal  stress  the  metamorphism  will, 
other  things  being  equal,  be  greater  in  districts  where  no  buckling 
or  overthrusting  of  beds  has  permitted  escape  from  the  intensity 
of  the  thrust. 

The  following  theory  of  coal  formation  has  recently  been  advanced  by 
Bowling  (4).  The  death  of  a  plant  is  marked  by  the  loss  of  power  to  form 
oxidized  hydrocarbon  compounds,  consequently  chemical  reactions  are  set 
up  in  the  material  of  the  dead  plant.  The  formation  of  compounds  of  oxygen 
and  carbon  is  the  first  evidence  of  decay.  With  the  escape  of  these  gases 
the  hydrocarbons  left  behind  become  unstable,  and  loss  of  marsh  gas  follows. 
If  fermentation  accompanies  decay,  new  hydrocarbon  compounds  are  formed 
by  this  parasitic  form  of  life  and  the  reduction  of  oxygen  is  accomplished 
without  great  loss  of  hydrogen,  which  is  the  element  that  gives  character 
to  the  material,  especially  when  in  the  coal  stage.  When  solidified  by 
superposed  load,  the  fermentation  is  arrested  and  pressure  and  heat  cause 
the  subsequent  alteration.  Static  pressure  favors  the  combination  of  oxy- 
gen with  carbon  or  hydrogen.  Heat  causes  the  combination  of  carbon  with 
oxygen  or  hydrogen.  Pressure  effects  the  alteration  without  loss  of  carbon, 
while  heat  wastes  it. 

Chemical  Changes.  —  The  chemical  changes  referred  to  above 
may  be  illustrated  by  the  following  chemical  equations  (19,  p.  26): 

VEGETABLE  TISSUE  =  Loss  BY  DECOMPOSITION  COALS 

(1)  5C6H1005    =    6CO2  +  CO    +    3CH4  +  8H2O  +  CWW)* 

Cellulose  Carbon  oxides  Marsh  gas         Water  Lignite 

(2)  6CCH1005    =      SCO*  +  CO  +  5CH4  +  10H20  +  CaHaoO 

Cellulose  Carbon  dioxide  Marsh  gas  Water  Bituminous 

(3)  7C6H1005    =        8CO2     +     4CH4  +  19H2O  +  CgoH16O 

Cellulose  Carbon  dioxide          Marsh  gas  Water        Semibituminous 

These  equations  are  not  intended  to  indicate  that  there  is  neces- 
sarily a  direct  passage  from  cellulose  to  semi-bituminous  coal, 
without  the  development  of  intermediate  stages;  and  to  bring  out 
this  lineal  succession  as  well  as  to  show  the  changes  by  a  graphical 
method  we  may  use  the  following  diagram  (Fig.  1)  prepared  by  the 
late  Professor  Newberry. 

In  this  diagram  the  rectangle  A  BCD  represents  a  given  volume 
of  fresh  vegetable  matter,  which  contains  a  small  percentage  of 
mineral  matter,  the  rest  being  organic  substances  consisting  roughly 
of  50  per  cent  carbon  (EFCD)  and  50  per  cent  hydrogen,  oxygen, 
and  nitrogen  (ABEF).  In  the  change  from  fresh  vegetable  tissue 
to  peat,  part  of  these  four  elements  pass  off  as  gaseous  compounds, 


18 


ECONOMIC   GEOLOGY 


so  that  the  remaining  volume  of  peat  is  less  (BGD  H)  than  the  origi- 
nal volume  of  vegetable  matter  (A BCD).  Since,  however,  H,  0, 
and  N  have  passed  off  in  larger  amounts  than  the  carbon,  the  per- 
centage of  the  latter  in  the  peat  will  be  higher  than  it  was  in  the 
fresh  plant  tissue.  (Compare  BFGI  and  FIDH  with  ABEF  and 
EFCD.)  The  actual  weight  si  mineral  matter  will  be  the  same, 


BITUW.  COAL          ANTHRACITE  GRAPHITE 


FIG.  1.  —  Diagram  showing  changes  occurring  in  passage  of  vegetable  tissue  ta 
graphite.     (After  Newberry.) 

but  its  percentage  will  be  larger.  This  change,  continued,  will 
result  finally  in  anthracite,  the  last  of  the  coal  series,  in  which  the 
per  cent  of  carbon  (LKMN)  is  high  and  that  of  the  other  organic 
elements  low  (JKL).  The  amount  of  compression  that  occurs  in 
such  changes  as  those  illustrated  in  the  diagram  may  be  understood 
when  it  is  stated  that  it  is  estimated  that  from  16  to  30  feet  of  peat 
are  required  to  make  one  foot  of  true  coal. 

The  following  elementary  analyses  of  peat,  lignite,  and  various 
grades  of  coal  clearly  illustrate  this  gradual  concentration  of  carbon 
by  losses  of  volatile  elements. 

ELEMENTARY  ANALYSES  OF  COALS 


KIND 

C 

Pi 

o 

N 

s 

ASH 

MOISTURE 

Peat     ....         .    . 

5947 

652 

31.51 

251 

22 

Lignite                         m 

5266 

522 

27  15 

.71 

202 

1224 

Subbituminous   .... 
Bituminous               ... 

58.41 
82.70 

5.06 

4.77 

28.99 
9.39 

1.09 
1.62 

.63 
.45 

4.79 
1.07 

— 

Semibituminous       .     .     . 
Anthracite 

83.14 
90.45 

4.58 
2.43 

4.65 
2.45 

1.02 

.75 

5.86 
4.67 

— 

Classification  of  Coals.  —  At  the^$£sent  time  a  number  of  kinds  of  coal 
are  recognized  in  the  United  S&ates  and  Canada,  whose  differentiation 
depends  on  their  physical  and  chemical  properties.  But  even  these  few 
type  names  are  often  used  in  a  rather  loose  way. 


COAL  19 

Perhaps  the  first  important  attempt  at  classification  was  that  of 
P.  Frazer,  Jr.,  based  on  the  fuel  ratio  (17).  This  was  as  follows:  — 

FUEL  RATIO 
Anthracite    .     .....     .     .     .     .     .     100-12 

Semianthracite 12-  8 

Semibituminous 8-5 

Bituminous 5-0 

Objections  which  have  been  urged  against  this  are  that  all  coals  with  a 
fuel  ratio  of  less  than  5  are  grouped  into  one  class  and  no  provision  made 
for  lignite.  It  also  groups  good  and  poor  bituminous  coals  together. 

Collier  (15)  proposed  that  all  coals  having  a  moisture  content  of  over 
10  per  cent  should  be  classed  as  lignite  and  those  with  less  as  bituminous, 
but  this  differentiation  has  been  shown  to  be  unreliable. 

M.  R.  Campbell,  while  agreeing  to  the  usefulness  of  the  fuel  ratio  classi- 
fication for  coals  above  the  bituminous  grade,  criticised  its  application  to 
coals  of  this  type  or  lower  ones,  and  suggested  a  provisional  classification 
based  on  the  carbon-hydrogen  ratio  (14).1 

Q 

GROUP  g 

A  (Graphite)    ....     .v>  .V.     .     .  oo 

^  1  Anthracite      ...:..-...  ?-30  (?) 

v.J 

D  Semianthracite        .......  26  (?)-23  (?) 

E  Semibituminous      .......  23  (?)-20 


Bituminous 


20-17 
17-14.4 
14.4-12.5 
12.5-11.2 


J  Lignite     .     .     .     . 11.2-9.3 

KPeat   ...........  9.3-? 

L  Wood 7.2 

This  table  is  likewise  faulty,  as  it  does  not  completely  separate  the 
peats,  lignites,  subbituminous,  and  even  some  of  the  bituminous  coals. 

Parr  (19),  in  attempting  to  make  a  satisfactory  classification,  points  out 
that  the  term  volatile  combustible  is  incorrect  as  it  consists  of  combustible 
hydrocarbons  and  noncombustible  H,  O,  and  N.  Thus  in  a  Pocahontas 
coal  with  18.70  per  cent  volatile  combustible,  14.5  per  cent  is  hydrocarbons 
and  4.2  per  cent  hydrogen,  oxygen,  and  nitrogen.  Again,  a  North  Dakota 
lignite  had  41.91  per  cent  volatile  combustibles,  made  up  of  20.28  per  cent 
hydrocarbons  and  21.63  per  cent  hydrogen,  oxygen,  and  nitrogen.  In  a 
logical  classification,  therefore,  allowance  should  be  made  for  this  inert 
volatile  matter. 

In  Parr's  classification  the  terms  used  are :  vc,  or  volatile  carbon  unasso- 
ciated  with  hydrogen,  obtained  from  C  —  fc  (total  carbon  minus  fixed  carbon) ; 

1  Campbell  found  that  subdivisions  based  on  total  carbon,  total  hydrogen,  and 
calorific  value  were  all  unsatisfactory. 


20 


ECONOMIC   GEOLOGY 


C,  or  total  carbon  as  determined  by  analysis;  and  inert  volatile  matter,  ob- 
tained by  subtracting  from  100  per  cent  the  sum  of  total  carbon,  available 
hydrogen,1  sulphur,  ash,  and  water. 

It  will  be  seen  that  Parr's  classification,  which  follows,  requires  data  from 
both  the  elementary  and  the  proximate  analysis  of  the  coal. 

PARR'S  CLASSIFICATION. 


Coals 


Anthra- 
citic 


f 

Anthracites  Proper  Ratio  ^  below  4  %. 


Semianthracite 
Sermbituminous 


Bitumi- 
nous 


Bituminous  Proper 


I 

|  Ratio  —•  between  4  %  and  8  %, 

I 

f  Ratio  ^  from  10  %  to  15  %. 


Ratio  ^  from  20  %  to  32  %. 
C 

Inert  volatile  from  5  %  to  10  %. 


B 


Black  Lignites 


Brown  Lignites 


Ratio  ^  from  20  %  to  27  %. 
Inert  volatile  from  10  %  to  16  %. 

Ratio  ^  from  32  %  to  44  %. 
Inert  volatile  from  5  %  to  10  %. 

Ratio  ^  from  27  %  to  44  %. 
Inert  volatile  from  10  %  to  16%. 


Ratio  ~  from  27  %  up. 
[  Inert  volatile  from  16  %  to  20  %, 


Ratio  ^  from  27  %  up. 

Inert  volatile  from  20  %  to  30  %. 


Grout  expresses  the  fuel  ratio  as  follows  (18): 

Fixed  carbon 
100  — Fixed  carbon* 
He  makes  the  following  classification  based  on  pure  coal: — 

Graphite Fixed  carbon,  over  99  per  cent. 

Anthracite Fixed  carbon,  over  93  per  cent. 

1  That  part  of  hydrogen  content,  excluding  the  hydrogen  united  with  oxygen  to  form 
water,  which  is  free  to  enter  into  combustion  with  oxygen  for  the  production  of  heat. 


COAL  21 

. 

Semianthracite Fixed  carbon,  83  per  cent  to  93  per  cent. 

Semibituminous Fixed  carbon,  73  per  cent  to  83  per  cent. 

Bituminous 

High  grade  {  Fixed  carbon»  48  per  cent  to  73  per  cent. 

I  Total  carbon,  82  per  cent  to  88  per  cent. 

Low  grade  I  Fixed  carbon>  48  Per  cent  to  73  Per  cent. 

{  Total  carbon,  76.2  per  cent  to  82  per  cent. 

Cannel  |  Fixed  carbon,  35  per  cent  to  48  per  cent. 

[  Total  carbon,  76.2  per  cent  to  88  per  cent. 

Black  lignite  .  {  Fixed  carbon>  35  Per  cent  to  60  Per  Gent- 

{  Total  carbon,  73.6  per  cent  to  76.2  per  cent. 

Brown  lignite  j  Fixed  carbon'  30  Per  cent  to  55  Per  cent- 

(  Total  carbon,  65  per  cent  to  73.6  per  cent. 

Peat  and  turf  {  Fixed  carbon'  below  55  Per  cent' 

[  Total  carbon,  below  65  per  cent. 

Wood 

D.  B.  Bowling  (16)  notes  that  one  objection  to  Campbell's  §  classifica- 

H 

tion  is  the  necessity  for  having  an  elementary  analysis,  which  is  rarely 
made,  costly,  and  time  requiring.  As  a  substitute  for  Campbell's  classifi- 
cation, he  substitutes  what  he  has  provisionally  termed  the  "  split  volatile 
ratio  "  viz  Fixed  carbon  +  \  volatile  combustible . 

Moisture  +  \  volatile  combustible 
An  arrangement  of  a  series  of  coals  by  this  method  and  also  Campbell's 

C 

-p  ratio  does  not  indicate  great  disagreement;  moreover,  Bowling's  classifica- 
tion has  the  advantage  of  being  based  on  the  proximate  composition.  He 
makes  the  following  subdivisions:  — 


GROUP 


SPLIT  VOL.  RATIO 


Anthracite     .     . 
Semianthracite  .     .     .     , 
Anthracite  coal       . 
High  carbon  bituminous 
Bituminous   .     .     . 
Low  carbon  bituminous 
Lignitic  coal       .     .     .    ', 
Lignite      .     .     .     .' 


15  up 
13-15 
10-13 
6-10 
3.5-6 

3-3.5 
2.50-3 
1.00-2.50 


More  recently,  Campbell  has  suggested  the  recognition  of  two  classes  of 
coal  below  bituminous,  calling  the  upper  grade  "subbituminous"  and  the 
lower  grade  "lignite."  He  suggests  that  the  manner  of  weathering  be  used 
as  a  criterion  for  separating  the  bituminous  from  the  subbituminous,  the 
former  cleaving  into  prisms,  while  the  latter  checks  irregularly  on  drying, 
and  when  weathered  on  the  outcrop  cleaves  into  plates  parallel  to  the 
bedding.  The  subbituminous  coals  with  their  black  color  he  claims  can 
be  distinguished  from  lignites,  because  the  latter  are  brown, 


22 


ECONOMIC  GEOLOGY 


Coal  I 
Fire  Clay 


White's  Classification.  —  White  (20)  has  shown  that  if  a  series  of  coals  of 
different  ages,  kinds,  and  regions  are  plotted  according  to  the  C  :  (O  +  ash) 
ratios  and  calorific  values  as  components,  they  describe  a  curve,  which 
shows  a  close  relation  between  the  increase  of  the  above  mentioned  ratio 
and  the  calorific  power.  Weathered  coals,  those  having  over  78  per  cent 
fixed  carbon  in  pure  coal,  and  the  boghead-cannel  group  (high  in  hydrogen) 
are  the  greatest  variants.  Oxygen  is  ranked  with  ash  in  this  ratio  because 
the  two  are  approximately  equal  in  anti-calorific  potency.  This  ratio  can- 
not be  used  as  a  basis  for  separation  into  kinds,  such  as  peat,  lignite,  etc. 

Structural  Features  of  Coal  Beds.  —  Outcrops  (24,  25).  —  The 
outcrop  of  a  coal  bed  is  usually  easily  recognizable  on  account  of  its 
color  and  coaly  character;  but  unless  the  exposure  is  a  rather  fresh 
one,  the  material  is  disintegrated  and  mellowed,  the  wash  from  it 
mingling  with  the  soil,  and  if  the  outcropping  bed  is  on  a  hillside, 
often  extending  some  feet  down  the  slope.  This  weathered  outcrop 
has  been  termed  the  "smut"  or  "blossom"  by  coal  miners.  In 
areas  where  the  beds  have  been  tilted  and  the 
slopes  are  steep,  the  outcrops  of  coal  can  usually 
be  easily  traced;  but  in  regions  where  the  dip  is  low 
and  the  surface  level,  the  search  for  coal  is  often 
attended  with  difficulty,  which  is  increased  if  the 
country  is  covered  with  glacial  drift.  In  such  cases 
boring  or  pitting  is  commonly  resorted  to. 

The  number  of  coal  beds  found  in  any  given 
region  varies,  and  may  at  times  be  large.  Thus  in 
the  Pennsylvania  section,  as  many  as  20  beds  are 
known;  in  Alabama,  at  least,  55  have  been  counted, 
but  not  all  are  workable;  while  in  Indiana  there  are 
25,  of  which  9  are  minable  over  large  areas.  The 
beds  are  rarely  parallel,  and,  moreover,  thin  out  if 
followed  any  distance. 

Associated  Rocks.  —  Most  coal  beds  are  inter- 
bedded  with  shales,  clays,  or  sandstones,  though 
conglomerates  or  limestones  are  at  times  also  found 
in  close  proximity,  the  latter  sometimes  even  when 
of  marine  character,  resting  directly  on  them. 
Coal  beds  are  often  underlain  by  a  bed  of  clav 

L'n,.  _.  —  Section        !_•   v    •  •  .        „ 

in  coal  measures  wmch  m  some  regions  is  of  refractory  character 
of  western  Penn-  (Fig.  2);  but  the  widespread  belief  that  all  these 
sylvania,  show-  un(jer  clays  are  fire-clays  is  unwarranted. 

ing      nre      clay  T7. 

under  coal  beds.  ((  Variations  in  Thickness.  —  Coal  beds  or 
(After Hopkins.)  "seams "  are  rarely  of  uniform  thickness  over 


Coal 


Coal 
Fire  Clay 


Coal 


FIG.  2. 


COAL 


23 


large  areas;  indeed,  a  bed  which  is  of  sufficient  thickness  to 
work  in  one  mine  may  be  so  thin  in  a  neighboring  one  as  to  be 
scarcely  noticeable.  This  irregularity  is  in  some  cases  due  to 
variations  in  thickness  of  vegetable  accumulations,  in  other  cases 
to  local  squeezing  of  the  coal  bed  subsequent  to  its  formation. 


FIG.  3.  —  Section  showing  irregularities  in  coal  seam,     a,  split;  b,  parting  of  shale; 
c,  pinch;  d,  swell;   e,  cut  out. 

These  thinnings  and  thickenings  are  commonly  called  "pinchings" 
and  "  swellings"  (Fig.  3).  In  regions  of  pronounced  folding,  the 
beds  are  usually  found  in  separate  synclinal  basins,  the  intervening 
anticlinal  folds  having  been  worn  away. 

While  coal  beds  may  vary  in  thickness  from  a  mere  film, 
to  even  more  than  100  feet  in  extreme  cases,  they  are  rarely 
over  8  or  10  feet  thick. 

The  Mammoth  seam  of 
the  Pennsylvania  anthracite 
region  is  50  to  60  feet  thick. 
The  Commentry  basin  of 
central  France  contains  a 
single  bed  of  Permian  coal 
that  locally  exceeds  80  feet 
in  thickness.  But  on  one 
side  of  the  basin  the  coal 
splits  up  into  six  beds  sep- 
arated by  sand  and  shales. 
This  indicates  that  coal  accumulation  went  on  continuously  on 
one  side  of  the  basin,  but  was  interrupted  six-  times  by  sand 
deposits  on  the  other  side. 

Other  Irregularities.  —  Splitting  (Fig.  3)  is  a  common  feature 
of  many  coal  seams.  The  Mammoth  bed,  so  prominent  in  most 
of  the  anthracite  basins  of  Pennsylvania,  splits  into  three  separate 
beds  in  the  Wilkesbarre  basin.  This  splitting  is  caused  by  the 
appearance  of  beds  of  shale  (called  "  slate  "  by -coal  miners), 
which  often  become  so  thick  as  to  split  up  the  coal  seam  into 


FIG.  4. — Section  of  faulted  coal  seam. 
(After  Keyes,  la.  Geol.  Surv.,  II.} 


24 


ECONOMIC  GEOLOGY 


two  or  more  beds.  When  narrow,  such  a  bed  of  slate  is  called 
a  parting.  The  Pittsburg  seam  of  western  Pennsylvania  shows 
a  fire-clay  parting  or  "  horseback  "  from  6  to  10  inches  over 
many  square  miles. 

An  interesting  case  of  parting  is  found  in  the  13-foot  seam  at  Inverness, 
Nova  Scotia.  At  the  outcrop  this  showed  three  shale  partings,  of  1  foot, 
9  inches  and  11  inches  respectively.  At  2500  feet  down  the  dip,  these 
partings  had  increased  to  19,  3,  and  22  feet  respectively.  A  7-foot  seam, 
lying  284  feet  below  the  13-foot  one,  maintained  its  thickness,  however, 
for  this  same  distance  on  the  dip. 

A  split  may  occasionally  be  caused  by  overthrust  folds  as 
shown  in  Fig.  5. 


FIG.  5. — Section  of  coal  bed,  showing  the  development  of  a  "  split,"  due  to  an 
overthrust  roll.     (Pa.  Top.  and  Geol.  Surv.,  Rep.  10.) 


In  addition  to  these  "  slate  "  partings,  which  run  parallel  with 
the  bedding,  others  are  often  encountered  which  cut  across  the  beds 
from  top  to  bottom.  These  in  some  cases  represent  erosion  channels 
formed  in  the  coal  during  or  subsequent  to  its  formation,  and  later 
filled  by  the  deposition  of  sand  or  clay.  In  other  cases  they  are  due 
to  the  filling  of  fissures  formed  during  the  folding  of  the  strata. 

Coal  beds  may  pass  into  shale,  the  latter  representing  possibly 
islands  of  mud  or  ridges  which  arose  above  the  level  of  the  marsh  in 
which  the  coal  plants  accumulated. 

Faulting  (Fig.  4)  is  not  an  uncommon  feature  of  coal  beds, 
and  the  coal  is  sometimes  badly  crushed  on  either  side  of  the  line  of 
fracture.  The  amount  of  throw  and  the  number  and  kinds  of  faults 
may  vary,  so  that  one  might  expect  normal,  reverse,  overthrust, 
and  even  step  faults. 


.  *  FTTH           •*  /  ^    SZa  —  —  I  —  

J  

101°    Lon?itud« 

117°                                                113°                                                 109°                                                 105° 

BITUMINOUS  AND  ANTHRACITE  COAL 
A     Indicates  anthracite^  coal  C    coking  coal 

Oonto 

Areas                                Areas  that  may            'Areas  prrobably  containing 
containing  workable                   contain  workable             Workable  coal  beds  under 
ooal  beds                                   coal  beds                   such  heavy  cover  as  not 

to  be  available  at  present 


PLATE  IV.  —  Map  of  coal  i 


G.asnwich 


JMINOUS  COAL 


LIGNITE 


fa  i  that  may 
!a  n  workable 
no  al  beds 


Areas  probably  containing 
workabls  coal  beds  under 
such  heavy  cover  as  not 

to  be  available  at  present 


Areas 

containing  workable 
lignite  beds 


C^ 

Areas  that  may 

contain  workable 

lignite  beds 


States.      (11  S.  Onl    Snrvpv  ^ 


COAL  25 

Weathering  of  Coals.  —  Parr  and  Hamilton  (27),  as  a  result  of  their 
investigations  of  the  weathering  of  coal,  concluded  that  submerged  coal 
does  not  lose  appreciably  in  heat  value,  but  that  outdoor  exposure  results 
in  a  loss  of  heating  value  varying  from  2  to  10  per  cent.  Dry  storage  is 
only  of  advantage  for  high  sulphur  coals,  where  the  disintegrating  effect 
of  sulphur  in  process  of  oxidation  facilitates  escape  of  hydrocarbons  by 
oxidation  of  the  same.  Storage  losses  usually  appear  to  be  complete  at 
end  of  five  months. 

Coal  Fields  of  the  United  States.1  (PL  IV.)  —  Coal  in  com- 
mercial quantities  occurs  in  thirty-three  states  and  territories,  as 
well  as  in  Alaska.  These  occurrences  can  be  grouped  into  the 
following  fields: 

AREA, 

(J)  Appalachian,    including    parts    of  Pennsylvania,    Ohio,         SQ.  MI. 
Maryland,  Virginia,  West  Virginia,  Eastern  Kentucky, 
Tennessee,  Georgia,  and  Alabama 69,755 

(2)  Atlantic  Coast   Triassic,  including  parts  of  Virginia  and 

North  Carolina 210 

(3)  Eastern   Interior,   including   parts   of   Indiana,    Illinois, 

and  Western  Kentucky        47,000 

(4)  Northern  Interior,  including  a  part  of  Michigan      ...  11,000 

(5)  Western  Interior,  including  parts  of  Iowa,  Missouri,  Ne- 

braska, Kansas,  Oklahoma,  Arkansas,  and  Texas     .     .  74,900 

(6)  Gulf  Coast  Lignite  Field,  including  portions  of  Arkansas 

and  Texas 2,100 

(7)  Rocky  Mountain  field,  including  parts  of  Colorado,  Ari- 

zona, New  Mexico,  Utah,  Wyoming,  Idaho,  Montana, 

North  Dakota,  South  Dakota 126,022 

(8)  Pacific  Coast  Field,  including  parts  of  Washington,  Ore- 

gon, and  California 1,900 


332,887 
(9)  Alaska 1,210 

The  estimates  of  areas  given  above  are  from  calculations  made  by  the 
United  States  Geological  Survey,  and  are  to  be  regarded  as  fairly  accurate, 
but  some  of  these  fields  may  be  extended  in  the  future  by  the  development 
of  areas  now  classed  as  unproductive.  This  applies  especially  to  those  in 
which  the  coal  lies  too  deep  to  be  profitably  mined  at  present.  It  is  a 
noteworthy  fact  that  the  production  of  the  fields  is  by  no  means  propor- 
tional to  their  areas  (compare  above  list  with  table,  p.  54).  Proximity 
to  markets,  value  of  the  coal  for  fuel,  and  relative  quantity  of  coal  per 
square  mile  of  productive  area  are  factors  of  importance  in  determining 
the  output  of  a  field. 

1  The  Rhode  Island  area  of  graphitic  anthracite,  formerly  included  in  this  list, 
is  referred  to  under  Graphite. ,  t 


26 


ECONOMIC   GEOLOGY 


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28  ECONOMIC  GEOLOGY 

Geologic  Distribution  of  Coals  in  the  United  States.  —  The 
accompanying  table,  which  shows  both  the  geologic  and  geo- 
graphic distribution  of  coals  in  the  United  States,  indicates  that 
the  Carboniferous  coals  are  found  chiefly  in  the  eastern  half 
of  the  country,  and  the  younger  coals  in  the  western  half.  The 
separation  of  the  Carboniferous  coals  into  well-defined  areas  is 
probably  the  result  of  folding  and  erosion,1  and  to  a  certain 
extent,  the  same  is  true  of  the  Rocky  Mountain  Coal  fields. 
The  latter  have  often  been  seriously  disturbed  by  post-Creta- 
ceous uplifts. 

Appalachian  Field  (33,  36,  39,  91,  99,  101,  109,  etc.) .  —  This, 
the  most  important  coal  field  in  the  United  States,  extends  850 
miles,  from  northeastern  Pennsylvania  to  Alabama.  It  shows 
a  maximum  of  180  miles  at  the  northern  end,  narrows  to  less  than 
30  miles  in  Tennessee,  and  expands  again  to  85  miles  in  Alabama. 
About  75  per  cent  of  its  area  contains  workable  coal.  At  the 
southern  end  the  coal  measures  pass  beneath  the  coastal  plain 
deposits,  and  they  may  connect  with  the  Arkansas  Coal  Measures 
beneath  the  Mississippi  embayment. 

Being  closely  associated  with  the  Appalachian  Mountain 
uplift,  the  coal  measures  of  this  region  partake  of  the  structural 
features  of  the  Appalachian  belt.  The  eastern  margin  of  the  field 
borders  on  a  belt  of  steeply  folded  strata,  forming  the  Appalachian 
Valley,  and  hence  the  coal-bearing  formations  are  much  folded 
here  (Fig.  6,  10),  while  at  the  southern  end  of  the  field  they  are 
faulted  in  addition  (Fig.  6).  Extensive  erosion  following  the 
folding  of  the  Coal  Measures  has  resulted  in  the  development  of 
a  number  of  basins. 

The  Coal  Measures  of  the  Appalachian  field  consist  of  a  great 
thickness  of  overlapping  lenses  of  conglomerate,  sandstone, 
limestone,  shale,  fire  clay,  and  coal.  The  formations  in  general 
show  a  thinning  from  the  eastern  margin  of  the  field,  westward, 
as  well  as  showing  a  decrease  in  the  number  and  thickness  of  the 
beds.  Owing  to  the  lenticular  character  of  the  deposits,  and  the 
local  thickenings,  it  is  difficult  to  trace  individual  beds  of  coal 
over  wide  areas,  or  correlate  sections  at  widely  separated  points. 

The  middle  Carboniferous  or  Pennsylvanian  includes  most 
of  the  coal  beds  of  the  Appalachian  field,  but  there  are  some 
also  in  the  upper  Carboniferous  and  in  the  Pocono  of  the  lower 
Carboniferous  or  Mississippian. 

1  Ashley,  Econ.  Geol.,  II:  650,  19Q7. 


COAL 


29 


8 


The  classic  section  of  the  Coal  Measures,  first  worked  out 
in  Pennsylvania,  was  as  follows: — 

(1)  Dunkard  or  Upper  Barren  Measures.  d  ^ 

(2)  Monongahela    or   Upper    Productive 
Measures. 

(3)  Conemaugh]  or  Lower  Barren  Meas- 
ures. 

(4)  Alleghany     or     Lower     Productive 
Measures. 

(5)  Pottsville  conglomerate. 

At  the  time  it  was  made  the  second  and 
fourth  members  were  thought  to  be  the 
only  ones  carrying  coal,  and  hence  the  name 
"  Productive  ";  but  since  then  the  Potts- 
ville has  been  found  to  be  locally  productive, 
and  a  few  seams  have  been  found  even  in 
the  Barren  Measures.  By  some  the  Dunkard 
series  is  now  placed  in  the  Permian. 

The  divisions  named  above  are  recogniz- 
able also  in  Ohio,  West  Virginia,  and  Mary- 
land, but  farther  south  the  identification  of 
all  becomes  difficult. 

The  Appalachian  field  is  divisible  into 
two  parts  of  very  unequal  size,  viz.  (1)  the 
anthracite  field  of  northeastern  Pennsyl- 
vania ;  and  (2)  the  bituminous  area,  which 
occupies  the  balance  of  the  field.1 

Pennsylvania  Anthracite  Field  (100). — 
This  field  (Fig.  7)  lies  in  the  northeastern 
part  of  the  state,  covering  an  area  of  about 
3300  square  miles,  about  one-seventh  of 
which  is  underlain  by  workable  coal  meas- 
ures. The  field  has  four  main  subdivisions, 
known  respectively  as  the  northern,  eastern 
middle,  southern,  and  western  middle.  In- 
tense folding  (Fig.  8)  has  placed  some  of 
the  coal  in  synclinal  troughs,  where  it  has 
been  preserved  from  erosion  which  [has  removed  the  coal  from 
the  intervening  anticlines.  Therefore  the  anthracite  is  found  in 
a  number  of  more  or  less  separated  narrow  basins.  It  has  been 

1  This  includes  some  small  areas  of  semianthracite. 


II 


30 


ECONOMIC  GEOLOGY 


estimated  that  from  94  to  98  per 
cent  of  the  coal  originally  de- 
posited has  been  removed  from 
this  field  by  denudation. 

The  Coal  Measures  of  the  an- 
thracite district  consist  of  beds 
of  sandstone,  shale,  and  clay, 
with  coal  beds  at  intervals  vary- 
ing from  a  few  feet  to  several 
hundred  feet,  though  rarely  ex- 
ceeding 200  feet.  The  coal  beds, 
which  vary  in  thickness  from  a 
few  inches  to  50  or  60  feet,  occur 
throughout  the  entire  section  of 
the  Coal  Measures,  but  are  most 
important  in  the  lower  300  to  500 
feet.  Among  these  the  Mammoth 

FIG.  7.—  Map  of  Pennsylvania  anthra-     jg  of    importance,    but    Splits    in 
cite   field.     (After  Stock,  U.  S.  GeoL 

some  areas. 


p.,  22dAnn.  Rept.,  III.) 

The  anthracite  section,  though  not  yet  accurately  correlated  with  the 
bituminous  field  of  Western  Pennsylvania,  is  nevertheless  known  to  con- 

rrni 

*--$$   !i  I3i 

5  +          a     fe  a       ^DnckKdi. 


23     J.»M«T;ll..B«ia     Se»«r  "Brook     YorVtown  Anticl 
»S  ^      „,-  Anticlin.  (0«rt«rn«l) 

|       "': 


TreKkowB.tia     & 

3*     *  ^ 

i  iiiiji 


8ectlon(C)acro««  the  Panther  Cn*k  Basin 


FIG.  8.  —  Sections   in   Pennsylvania   anthracite   field.     (After  Stoek,  U.  S.  GeoL 
Surv.,  22d  Ann.  Rept.,  III.) 

tain  the  Pocono,  Mauch  Chunk,  Pottsville,  and  Alleghany  series,  as  well  as 
some  of  the  higher  ones  of  the  Coal  Measures  (39) .     The  Pottsville  conglom- 


COAL 


31 


erate  forms  an  important  stratigraphic  horizon,  recognizable  by  its  litho- 
logical  characters  and  bold  outcrops. 

The  position  of  the  coal  beds  and  physical  characteristics  of  the  coal  have 
necessitated  the  use  of  special  methods  of  mining  and  of  treatment  after 
mining  (100).  Sharpness  of  folding  and  steep  dips  prevail,  these  intro- 
ducing many  mining  problems  not  found  in  bituminous  regions.  When 
brought  to  the  surface^  the  anthracite  consists  of  lumps  varying  in  size  and 
mixed  with  more  or  less  shaly  coal  called  bone,  so  that  before  shipment 
to  market  it  is  necessary  to  break,  size,  and  sort  it.  This  is  done  in  a  coal 
breaker  (Fig.  9),  in  which  the  coal  is  crushed  in  rolls  and  sized  by  screens, 
while  the  slate  is  separated  either  by  hand,  automatic  pickers,  or  jigs. 
These  breakers  are  a  prominent  feature  of  the  anthracite  region,  and  much 
money  has  been  spent  in  increasing  their  efficiency.  As  the  result  of  years 
of  mining,  the  refuse  from  the  breakers,  consisting  of  a  fine  coal-dust  and 
bone,  termed  "  culm,"  has  accumulated  in  enormous  piles.  Much  of  it  is 
now  being  washed  to  save  the  finer  particles  of  clean  coal ;  and  much  is  also 
washed  into  the  mines  to  support  the  roof,  so  that  the  pillars  of  coal,  origi- 
nally left  for  that  purpose,  can  be  extracted. 

On  account  of  its  cleanliness  and  high  fuel  ratio,  anthracite  coal  is 
much  prized  for  domestic  purposes.  Most  of  that  mined  is  marketed  in  the 
eastern  and  middle  states,  although  small  quantities  are  shipped  to  the 
western  states,  especially  those  that  can  be  reached  by  way  of  the  Great 
Lakes. 


FIG.  9. —  Coal  breaker  in  Pennsylvania  anthracite  region. 

Appalachian  Bituminous  Area  (36,  41).  Pennsylvania. — The 
Pennsylvania  bituminous  field  includes  an  area  of  about  12,000 
square  miles  lying  mostly  in  the  western  part  of  the  state  (PL  V) , 
and  having  an  exceedingly  irregular  boundary.  In  the  north- 
western part,  where  folding  is  slight,  the  coal  measures  form  outliers, 
capping  the  high  hills  and  ridges;  but  to  the  eastward,  the  more 
marked  synclinal  structure  has  resulted  in  the  formation  of  a 


32  ECONOMIC  GEOLOGY 

strung  out  series  of  basins.  The  most  northeastern  areas  are  quite 
isolated,  and  include  the  Bernice  (semi-anthracite),  Barclay,  and 
Blossburg  basins,  as  well  as  an  easterly  one,  the  Broadtop  (PL  V). 
The  coals  range  in  age  from  Pottsville  to  Dunkard,  and  in  about 
four-fifths  of  the  territory  the  thickness  of  the  Upper  Carboniferous 
rocks,  including  Dunkard,  is  less  than  1000  feet,  while  in  one-third 
it  is  under  500  feet  (41) .  Faults  are  rarely  found.  On  account  of  the 
variation  in  thickness  of  the  sandstones  and  other  rocks,  splitting 
of  coal  seams,  and  other  irregularities,  correlation  is  difficult.  But 
in  a  general  way  the  beds  above  the  Pittsburg  seam  appear  to  be 
more  regular  in  their  appearance  and  more  constant  in  their  dis- 
tance from  one  another,  than  the  beds  in  the  lower  part  of  the  section. 
The  number  of  coal  seams  recognized  in  the  several  series  is  as 
follows  (99):- 

Dunkard  series,  1100-1200  feet  thick,  12  coals 

Monongahela,       200-  300  feet  thick,  6  coals 

Conemaugh,          500-  700  feet  thick,  6  coals,  mostly  unimportant 

Alleghany,  300  feet  thick,  4  coals 

Pottsville,  several 

The  Alleghany  yields  about  forty  per  cent  of  the  bituminous  coals 
mined  in  Pennsylvania.  While  most  of  the  coal  beds  are  of  limited  extent, 
the  celebrated  Pittsburg  seam  at  the  base  of  the  Monongahela  has  an  aver- 
age thickness  of  7  feet  over  about  2100  square  miles  of  its  area  and  an  esti- 
mated, tonnage  of  9,641,792,907  short  tons,  thus  making  it  one  of  the  most 
important  bituminous  coal  beds  in  the  world.  This  same  seam  is  also 
recognizable  and  important  in  Ohio,  West  Virginia,  and  Maryland. 

Ohio.  —  In  Ohio  (40,  90-92)  the  five  subdivisions  of  the  middle  and 
Upper  Carboniferous  are  also  recognized,  and  there  are  at  least  16  coal  beds, 
of  which  6  are  important.  These  include  the  Pomeroy,1  Pittsburg,  Meigs 
(Sewickley  of  Pennsylvania),  Clarion,  Lower  Kittanning,  Middle  Kittan- 
ning,  Upper  Freeport,  Wellston,  and  Block  (Sharon).  The  Pittsburg 
coal  is  of  high  importance  and  the  Middle  Kittanning  includes  the  well- 
known  Hocking  Valley  coal. 

Maryland.  —  In  Maryland  the  coals  lie  in  three  broad  northeast-south- 
west synclinal  folds,  the  coal  measures  of  these  being  separated  by  Missis- 
sippian  or  Devonian  Rocks,  exposed  by  erosion  of  the  intervening  anti- 
clines. The  eastern  or  Potomac  basin  is  the  most  important  of  the  three. 
The  geologic  position  and  number  of  coals  is  as  follows:  Monongahela, 
with  Pittsburg  (Elk  Garden),  Tyson,  and  Koontz  coals;  Conemaugh,  2 
coals;  Alleghany  with  Upper  Freeport  (Thomas  or  three  foot),  Middle 
Kittanning  (Davis  or  six  foot),  Brookville  (Parker),  and  Clarion  (Blue- 
baugh);  Pottsville,  with  two  seams.  The  coals  are  good  steaming  fuels 
and  will  coke  (71). 

1  Formerly  regarded  as  Pittsburg,  but  shown  by  Bownocker  to  be  equivalent  of 
Redstone  of  Pennsylvania  and  West  Virginia.  (Ohio  Geol.  Surv.,  4th  ser.,  Bull. 
9,  p.  96,  1908  ) 


PLATE  VI. 


FIG.  1.  —  Pit  working  (strippings)  near  Milnesville,  Pa.     The  Mammoth  seam  is 
uncovered  in  bottom  of  pit. 


FIG.  2.  —  View  in  Arkansas  coal  field.     (H.  Ries,  photo.) 


(33) 


34 


-  a 


o  ^ 


9 1 

o  q 

1^    So 


ECONOMIC  GEOLOGY 

West  Virginia.  —  In  this  state  the  Coal  Measures 
occupy  an  irregular  rectangle  extending  from  the  Alleghany 
Mountain  region  northwestward  to  the  Ohio  River.  The 
deepest  part  of  the  Appalachian  basin  takes  a  southwest 
course  across  the  state,  the  axis  rising  to  the  southward. 
From  this  the  strata  rise  to  the  northwest,  while  to  the 
southeast  the  basin  shows  a  series  of  folds  of  increasing 
steepness  and  height  towards  the  eastern  boundary  of 
the  fields. 

The  coal  beds  range  from  the  Pocono  to  the  Dunkard 
in  age.  The  Pocono  contains  some  unimportant  beds  of 
anthracite  along  the  eastern  border  of  the  field,  but 
westward  the  formation  is  noted  for  its  petroleum  and 
absence  of  coal. 

The  Pottsville  carries  the  coals  of  the  New  River  and 
Pocahontas  series,  these  underlying  an  area  of  about  2600 
square  miles  in  the  southeastern  and  eastern  part  of  the 
field.  These  coals  are  of  high  quality,  being  low  in  sulphur 
and  ash.  In  northern  West  Virginia  the  Alleghany  series 
carries  several  coal  beds,  but  with  one  exception  these 
disappear  to  the  southwest  ward.  The  Conemaugh  carries 
two  coal  beds  of  importance,  while  the  Monongahela  carries 
six  distinct  beds,  including  the  famous  Pittsburg  seam. 
No  coals  of  much  importance  are  found  in  the  Dunkard. 

Virginia  (111).  —  The  coals  of  the  Mountain  Province 
are  of  either  Mississippian  or  Pennsylvanian  age.  The 
first  or  least  important  forms  a  belt  of  small  areas  of 
either  semibituminous  or  semianthracite  character  ex- 
tending from  Wythe  to  Frederick  counties,  but  the  only 
one  of  much  importance  is  the  Montgomery-Pulaski 
counties  area. 

The  Pennsylvanian  coals  lie  in  the  extreme  southwestern 
part  of  the  state  in  the  Cumberland  Plateau  region,  and 
are  the  most  important  producers.  The  two  chief  fields 
are  the  Pocahontas  or  Flat  Top  and  the  Big  Stone  Gap 
coal  fields. 

The  coal  measures,  which  are  probably  mostly  of 
Pottsville  age,  show  comparatively  little  disturbance, 
although  they  lie  immediately  west  of  the  highly  folded 
rocks  of  the  Great  Valley  (Fig.  10),  but  the  Pocahontas 
field  is  abruptly  terminated  on  the  east  by  a  fault.  In 
the  Pocahontas  field  there  are  at  least  six  workable  beds; 
the  coal  is  of  excellent  quality  for  steaming  purposes,  shows 
often  a  remarkably  low  ash  content,  and  makes  a  good 
coke.  The  Big  Stone  Gap  field,  which  extends  into  Ken- 
tucky, contains  eight  workable  seams  and  is  even  a  more 
important  producer  of  coal  and  coke. 

Southern  Appalachian  Field.  —  In  the  southern 
Appalachian  field  the  coal-bearing  rocks  are  mainly 


COAL  35 

of  Pottsville  age,  and  in  the  Birmingham,  Ala.,  district,  have  a  thick- 
ness of  probably  5000  to  6000  feet.  The  Coal  Measures,  which 
show  much  disturbance  on  their  eastern  margin,  with  but  little 
toward  the  west,  are  divisible  into  a  lower  (Lee,  Lookout,  or 
Millstone  Grit)  group,  carrying  about  three  thin  seams  in  the 
lower  part,  and  an  upper  group,  with  many  beds  of  coal. 

Although  the  coals  and  associated  rocks  were  originally  deposited 
in  a  broad  trough,  this  has  been  subsequently  folded,  and  faulted, 
while  the  basins  are  separated  partly  by  faulting  and  partly  by 
erosion  of  intervening  anticlinal  crests. 

There  are  three  main  districts,  known  as  the  Jellico,  Chattanooga, 
and  Birmingham,  the  latter  containing  four  fields,  viz.,  the  Warrior, 
Coosa,  Cahaba,  and  Blount  Mountain. 

The  Triassic  Field  (111,  112).  —  This  coal  field,  which  is  more  important 
historically  than  economically,  having  been  worked  as  early  as  1700, 
includes  several  small  steep-sided  basins  (Fig.  11),  lying  in  the  Piedmont 


FIG.  11. —  General  structure  section  of  the  Richmond  Basin  in  the  vicinity  of 
James  River.  A,  A,  A,  minor  flexures,  with  beds  downthrown  to  the  west; 
/,  /,  /,  faults.  The  heavy  black  band  represents  the  supposed  position  of  the 
coal  beds.  North  and  south  of  this  section  the  beds  appear  to  be  deeply  faulted 
down  against  the  western  margin,  and  the  apparent  synclinal  structure  dis- 
appears. The  superficial  portion  of  this  section  is  based  on  observation  and 
reliable  information;  the  deeper  portion  is  hypothetical.  (After  Shaler  and 
Woodworth,  U.  S.  Geol.  Surv.,  19th  Ann.  Rept.,  PL  II.) 

region  of  Virginia  and  North  Carolina.  It  is  probable  that  the  coal- 
bearing  beds  of  the  several  areas,  originally  horizontal,  were  formerly 
continuous,  having  been  separated  by  folding,  faulting,  and  denudation. 
In  addition  to  this,  the  coal  is  cut  by  dikes  and  sheets  of  igneous  rock, 
which  have  locally  altered  it  to  natural  coke  or  carbonite. 

Eastern  Interior  Field  (34,  57-59,  65-69).  — This  field  is  an  oval, 
elongated  basin  (Fig.  12),  extending  northeast  and  southwest, 
with  the  marginal  beds  dipping  gently  toward  the  lowest  portion, 
which  lies  in  Illinois,  where  the  beds  are  nearly  horizontal.  It 
covers  most  of  Illinois,  southwestern  Indiana,  and  a  small  part  of 
Western  Kentucky,  with  some  small  outliers  in  Missouri,  near  St. 
Louis  and  St.  Charles,  and  two  in  Illinois. 


36 


ECONOMIC   GEOLOGY 


The  coal-bearing  rocks  rest  unconformably  on  lower  Carbonifer- 
fc  ous,  Devonian,  and  Silurian  strata,  the  basal 

member  being  a  sandstone,  probably  the  equiv- 
alent of  the  Pottsville.  The  coal-bearing  rocks, 
which  have  a  maximum  thickness  of  fully  2200 
^  feet  in  Illinois,  belong  to  the  Coal  Measures, 
""1  although  the  upper  part  may  be  of  Permian 
I1  age,  and  the  highest  workable  coals  beds  are 
jj  classed  as  Freeport  or  Conemaugh.  The  coal 
^  seams  occur  in  the  lower  portion  of  the  section, 
c|  and  hence  outcrop  around  the  margin,  the 
~-  mining  operations  being  therefore  confined  to 
eg  a  narrow  belt,  because  near  the  center  of  the 
^  basin  the  coal  beds  underlie  too  great  a  thick- 
^  ness  of  unproductive  strata  to  permit  of  prof- 
^  itable  working  under  present  conditions. 

Great  difficulty  has  been  encountered  in  at- 
3  tempts  at  correlation  of  the  coal  beds  of  different 
^  parts  of  the  field,  because  of  the  varying  section 
<§,  shown  from  place  to  place,  and  lack  of  continuity 
•"  of  the  beds.  In  consequence,  the  custom  has 
2  arisen  of  giving  the  coal  beds  numbers  instead 
2  of  names. 

The  coals  of  the  Eastern  Interior  field, 
o  although  varying  widely  in  quality,  are  all 
S  bituminous.  On  account  of  trieir  higher  per- 
*"  centage  of  ash  and  sulphur,  they  are  little  used 
jg  for  coking.  Most  of  the  coal  used  in  and  near 
J  this  field  is  supplied  from  it;  but  even  within 
%  the  field  the  Appalachian  coals  enter  into  com- 
|  petition.  The  cannel  coal  found  near  Cannels- 
o  burg,  Kentucky,  which  is  the  only  good  gas 
§  producer  found  in  this  field,  finds  a  ready 
market. 


1 

\ 

\ 

\ 

^ 

\ 

H  — 

-*i 

i* 

>  4 

\i 

ij 

ii 

J  '* 

.  ."-:    : 

V  ;«° 

•    i 

\   ^ 

/    / 

i 

' 

n 

i 

1 

•v* 

i 

In  Illinois  the  section  involves  (57) :  — 

a.  Upper  or  Barren  Coal  Measures. 

b.  Lower  or  Productive  Coal  Measures;  coal  bearing. 

c.  Millstone  Grit  or  Mansfield  Sandstone. 


^  The  old  survey  recognized  16  beds,  of  which  1-7 

are  commonly  worked,  but  later  work  throws  doubt 

on  this  classification;  the  areas  of  important  development  of  the  different 


COAL 


37 


beds  are  not  coincident,  but  as  a  general  rule  the  coals  above  No.  2  in 
the  western  part  of  the  state  are  persistent  in  extent  and  thickness  over 
large  areas,  while  in  the  eastern  portion  all  the  seams  are  irregular  in 
both  extent  and  thickness.  As  a  rule,  the  lower  seams  are  better  than 
the  upper  ones,  and  the  quality  also  increases  from  north  to  south.  The 
Illinois  seams  vary  from  3  to  8  feet  in  thickness,  and  all  are  bituminous. 

Ashley  subdivides  the  Indiana  section  as  follows :  — 

Permian-Merom  group;   Upper  or  Barren  Measures,  0'-400'. 

Coal  Measures  |  Wabasl1  g^P;  main  coal-bearing  measures,  100'-600'. 
l  Mansfield  group ;   basal  sandstone  member,  0'-200'. 

The  coal  field  is  roughly  divisible  into  two  areas,  viz.  an  eastern  or 
"block-coal"  area,  and  a  western  or  bituminous  area.  The  former  is 
also  bituminous,  but  shows  a  peculiar  block-like  jointing. 

The  Indiana  section 
shows  at  least  25  dis- 
tinct coal  beds  (59), 
nearly  all  of  them  2  feet 
or  more  thick  in  some 
places,  and  nine  of  them 
continuing  of  minable 
thickness  over  large 
areas.  The  upper  five 
of  the  nine  numbered 
ones  are  coking  and 
occur  in  broad  sheets, 
while  the  lower  four 
occur  in  basins  and  are 

not  extensively  workable.  No.  5  is  the  most  important  bed  in  the  state 
and  can  be  correlated  the  entire  length  of  the  field. 

In  Kentucky  the  coals  have  been  numbered  from  1-12,  beginning  at  the 
bottom  and  lettered  beginning  at  the  top.  Nos.  9,  11,  .and  12  are  the 
chief  ones  worked.  One  of  these  is  exceedingly  persistent,  being  found 
under  a  part  of  the  whole  of  two  counties,  with  an  average  thickness  of 
5  feet,  and  at  a  depth  commonly  of  less  than  200  feet. 

Northern  Interior  Field  (72).  —  This  field  forms  a  large  basin  in 
which  the  coal  dips  irregularly  from  the  margin  toward  the  center 
(Fig.  14) ,  but  on  account  of  the  heavy  mantle  of  glacial  drift  it  has 
been  difficult  to  determine  its  exact  boundaries,  and  prospecting  is 
necessarily  done  by  means  of  drilling.  The  Coal  Measures,  which 
are  probably  of  Pottsville  age,  attaiji  a  total  thickness  of  600  to  700 
feet  in  the  center  of  the  basin,  and  include  7  horizons  of  workable 
coal  with  an  average  thickness  of  2  feet  and  rarely  exceeding  4  feet. 
The  Verne  coals  near  the  top  may  correspond  with  the  Mercer  coals 
of  Ohio  (Lane).  Coal  is  found  near  the  center  of  the  basin  at 
depths  of  400  feet  or  more,  though  the  beds  that  are  mined  are 
mostly  at  depths  of  100  to  250  feet.  All  the  coals  are  bituminous 


FIG.  13.  —  Shaft  house  and  tipple,  bituminous  coal  mine, 
Spring  Valley,  111. 


38 


ECONOMIC   GEOLOGY 


and  used  chiefly  for  fuel,  but  some  are  coking,  and  others  will  prob- 
ably prove  of  value  for  gas  manufacture.  Saginaw  and  Bay  City 
are  important  mining  towns. 

Western  Interior  Field  and  Southwestern  Fields  (35).  —  These 
two  fields  form  a  practically  continuous  belt  of  coal-bearing  forma- 


FIG.   14.  —  Generalized  section  of  Northern  Interior  coal  field. 
U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  III.) 


(After  Lane, 


tions,  extending  from  northern  Iowa  southwestward  for  a  distance 
of  880  miles  into  central  Texas.  Throughout  most  of  this  area  the 
beds  lie  horizontal,  or  have  a  gentle  westward  dip  averaging  10  to 
20  feet  per  mile,  but  a  notable  exception  is  found  in  the  beds  of  east- 
ern Oklahoma  and  Arkansas,  which  are  rather  strongly  folded, 
reminding  one  of  the  Pennsylvania  anthracite  area. 


FIG.  15.  —  Composite  section  showing  structure  of   lower  coal  measures  of  Iowa. 
(After  Keyes,  la.  Geol.  Surv.,  I.) 

Western  Interior  Field.  — The  Coal  Measures,  composed  of  lime- 
stones, shales,  fire  clays,  and  coal  beds,  rest  unconformably  on  the 
Mississippian  and  dip  westwardly  under  beds  of  Permian,  Creta- 
ceous, and  Pleistocene.  Toward  the  south  and  west  the  beds  increase 
in  thickness,  the  maximum  being  1000  feet  in  Iowa  (62),  3000  in 
Kansas  (63),  and  200  in  Missouri  (74).  In  a  general  way  there  is 
a  prevailing  dip  westward  of  10-20  feet  per  mile;  in  detail  the  dip 


Sugar  Works 


40 


ECONOMIC   GEOLOGY 


CLASSIFICATION   BY 
N.  F.  DRAKE. 

GENERAL  SECTION. 

Poteau  group 


is  south-southwest  in  Iowa,  west-northwest  in  Missouri,  and  usually 
northwest  in  Kansas. 

The  Coal  Measures  are  divisible  into  two  parts.  The  lower  is 
known  as  the  Des  Moines  in  Iowa,  and  the  Cherokee  and  Marmaton 
in  Kansas.  The  upper  is  termed  the  Missourian  in  Iowa,  but  in 
Kansas  is  made  up  of  the  Pottawatomie,  Douglas,  and  Shawnee. 
In  both  states  most  of  the  coal  mined  comes  from  the  Cherokee  shales 
horizon.  Those  found  in  the  upper  measures  are  thin,  even  though 
persistent. 

Most  of  the  coal  mined  in  this  field  comes  from  the  lower  part  of 
the  coal  measures,  where  the  beds  are  irregular  in  thickness  and 
distribution,     in     conse- 
quence of  deposition  on 
a  very  uneven  surface. 

All  the  coals  of  this 
field  are  essentially  bitu- 
minous and  used  chiefly 
for  steaming  and  heating 
purposes,  being  of  no 
value  for  either  coking  or 
gas  making.  Some  of  the 
seams  will  coke,  but  there 
is  no  demand  for  the 
product,  and  the  sulphur 
and  ash  are  too  high  for 
gas  making. 

The  Oklahoma  and  Ar- 
kansas portions  of  the 
Western  Interior  field  are 
directly  connected,  but 
the  coals  differ  somewhat* 

The  rocks  of  the  Okla- 
homa field  (60),  belong  to 
the  Coal  Measures  (Fig. 
16),  the  lowest  coal  beds 
being  probably  in  the 
upper  part  of  the  Lower  Coal  Measures,  and  the  highest  coal  in 
the  Upper  Coal  Measures. 

The  coal  field  is  characterized  by  both  folds  and  faults.  The 
anticlines  are  generally  narrower  and  deeper  than  the  synclines,  with 
a  tendency  to  overturn  to  the  north,  but  the  folds  die  out  to  the 


Cavanal  (Cavaniol) 
group. 


Lower  Coal  Measures, 


CLASSIFICATION.  BY 
J.  A.  TAFF 

DETAILED  SECTION. 


Boggy  formation. 
Upper  Witteville  coal. 

Lower  Witteville  coal. 


Savanna  formation. 


Cavanal  coal. 


McAlester  coals. 


McAlester  shale. 


Hartshorne  coals. 
Hartshorne  sandstone. 


Atoka  formation. 


FIG.  16.  —  Columnar  section  of  coal-bearing  rocks 
in  Oklahoma  coal  field.  (After  Taff,  U.  S. 
GeoL  Surv.,  22nd  Ann.  Rept.,  PL  III.) 


COAL 


41 


westward  and  northwestward.  There  are  seven  important  beds  oi 
workable  character,  as  well  as  some  that  are  workable  locally. 
The  coals  are  bituminous  and  coking. 

In  the  Arkansas  field  (49)  the  rocks  (sandstones  and  shales)  are  all 
of  Pennsylvanian  age,  and  involve  a  section  several  thousand  feet 
thick,  which  can  be  correlated  fairly  well  with  the  Oklahoma  area. 


Names  of  coal  beds         Section 


Upper  Hartshorne. 
Hartshorne 


Savanna 
100-1,000 


Paris 
600-700 


Fort  Smith 
375-425 


Spadra 
400-500 


Hartshorne 
100-300 


Atoka 
1,500-5,000  H 


General  character  of  formations 


In  Indian  Territory  this  formation  comprises  three 
sandstone  members  with  interbedded  shales;  only  the 
lower  part  la  present  In  Arkansas . 


Sand;  shale  with  thin  beda  of  shaly  sandstone.  Paris 
coal  bed  about  400  feet  from  top. 


Sandstone  Interbedded  with  shales.  Formation  yields 
building  stones,  flagstones,  and  brick  shale.  Coal  beds 
axe  usually  too  thin  for  mining. 


Shale  with  lenses  of  sandstone.  Hartshome  ooa!  at 
Is  most  important  bed  in  Arkansas . 


Typically  massive  sandstone,  but  varying  to  sandy  ahalt 
In  some  places 


Mainly  shale,  but  sandstone  lenses  comprise  from  ono- 
tenth  to  one-third  of  the  section.  Coal  beds  in  the 
eastern  part  of  the  field  may  be  thick  enough  in  gome 
places  for  mining. 


FIG.  17.  —  Generalized  columnar  section  of  the  coal-bearing  rocks  of  Arkansas. 
(After  Collier,  U.  S.  Geol.  Surv.  Bull  326.) 

They  are  bent  into  a  trough  in  which  there  are  a  number  of  sub- 
ordinate folds  and  some  -normal  and  thrust  faults.  The  coals  of 
the  Hartshorne  horizon  (Fig.  17)  are  economically  the  most  impor- 
tant, while  those  below  it  are  probably  thin  and  not  continuous. 
The  coals  range  from  bituminous  to  semianthracite,  and,  although 
not  of  coking  character,  excel  in  quality  any  found  west  of  West 
Virginia. 


42  ECONOMIC   GEOLOGY 

Southwestern  Field  (40).  —  This  area,  lying  in  northern  Texas, 
is  separable  into  a  northern  and  southern  portion  by  an  arm  of 
Cretaceous  strata,  extending  across  it.  The  coals,  which  are  all 
Pennsylvanian,  rest  uncomformably  on  the  Mississippian  and  are 
overlain  by  the  Permian  on  the  north.  There  are  five  divisions, 
which  carry  three  workable  coal  beds,  and  while  all  are  of  bitu- 
minous character,  none  of  them  are  coking. 

Rocky  Mountain  Fields  (38).  —  These  cover  a  broad  area  extend- 
ing from  the  Canadian  boundary  southward  into  New  Mexico, 
a  distance  of  about  1000  miles,  and  including  a  large  number  of 
fields  of  varying  size  and  irregular  shape.  Most  of  these  beds  lie 
within  the  mountainous  region,  but  at  the  northern  end  of  the  area, 
in  Wyoming  and  the  Dakotas,  the  coal  fields  extend  eastward  under 
the  Great  Plains  for  some  distance.  The  age  of  the  coal  ranges 
from  Lower  Cretaceous  to  Eocene  (Tertiary),  though  most  of  it 
belongs  to  the  former. 

While  portions  of  this  enormous  area  of  coal-bearing  strata  are 
only  slightly  disturbed,  mountain-building  forces  and  igneous  in- 
trusions have  affected  a  large  proportion  of  the  region,  often  materi- 
ally changing  the  character  of  the  coal.  Thus,  while  in  undis- 
turbed portions  of  the  field  the  beds  may  be  lignitic  (PL  VIII. 
Fig.  2),  in  the  disturbed  parts  they  haye  been  altered  to  bitu- 
minous. Igneous  intrusions  may  have  changed  the  latter  locally 
to  anthracite,  as  in  the  Crested  Butte  (55)  area  of  Colorado  or  the 
Cerrillos  field  of  New  Mexico  (80).  Some  of  the  bituminous 
coals  produce  an  excellent  quality  of  coke. 

Colorado  (54,  55)  is  the  most  important  coal-producing  state  of  the  Rocky 
Mountain  region,  the  distribution  of  its  coal  fields  being  shown  in  Fig.  18. 
The  Raton  field  in  the  southeastern  part  of  the  state,  extending  into  New 
Mexico  (82),  is  the  most  important  producer  and  yields  coking  coal.  Like 
many  of  the  fields  of  this  region  the  coals  which  are  of  Cretaceous  age  are 
both  folded  and  faulted.  They  are,  moreover,  crossed  by  igneous  intrusions, 
which  have  in  some  places  produced  natural  coke,  but  in  others  destroyed 
the  value  of  the  coal.  The  subbituminous  coals  of  the  South  Platte  field, 
and  the  bituminous  ones  of  the  Canon  City  area  are  also  important.  An- 
thracite is  obtained  in  the  Yampa  and  Crested  Butte  fields.  The  latter 
lies  at  the  eastern  end  of  the  great  Uinta  Basin  field,  which  extends  into 
Utah. 

Wyoming  (116-118)  has  a  larger  percentage  of  its  area  underlain  by  coal- 
bearing  rocks  than  any  other  Rocky  Mountain  state,  but  most  of  this  lies 
in  the  Great  Plains  region,  and  the  coals,  which  are  chiefly  Cretaceous,  are 
on  the  whole  of  subbituminous  character  (Fig.  19).  The  Green  River 
basin  in  southwestern  Wyoming  is  the  most  productive  area  and  yields 


PLATE  VIII 


FIG.  1.  —  View  in  sub-bituminous  coal  area,  between  Minera  and  Cannel,  Texas. 

(H.  Ries,  photo.) 


FIG.  2.  —  Lignite  seam,  Williston,  N.  Dak.     (After  F.  Wilder,  photo.) 

(43) 


44 


ECONOMIC  GEOLOGY 


bituminous  coal,  and  the  same  is  also  obtained  from  small  areas  in  the 
Powder  River  basin  of  northeastern  Wyoming. 

Utah  (109)  has  two  large  coal  areas  (Fig.  18).  The  largest  of  these  is 
that  of  the  Uinta  Basin,  which  carries  Upper  Cretaceous  bituminous  coals 
of  coking  character,  and  which  are  worked  chiefly  in  the  Book  Cliffs  fields 


K-      |  GRANDE  ^Alan,osyo-\   «i 

I  hs    :  wS^X--  .  •    L- 


reas  with  workable        Areas  of  workable  Probable  areas  of  Possible  areas  of.  Probable  areas  of  Areas  probably 

bitumlnout  and  subbltumlnous  coals  workable  ooal  w»rka'.l«  workable  coal,  but  under     containing  sub- 

some  anthracite  bituimious  and  anthracite       eubbitumlnoue  coals  heavy  cover  '      bituminous 

coal  under 
heavy  cover 

FIG.  18.  —  Map  showing  distribution  of  different  kinds  of  coal  in  Colorado. 
(After  Parker,  U.  S.  Geol.  Sum.) 


on  the  southern  rim  of  the  basin.     The  other  large  field  lies  in  southern 
Utah,  but  is  not  commercially  developed. 

Other  Rocky  Mountain  States.  —  A  great  area  of  Eocene  lignitic  coal  is 
found  in  the  Fort  Union  region  of  North  Dakota,  South  Dakota,  and  Mon- 
tana (75-77).  Passing  towards  the  mountainous  district  of  Montana,  the 
coals  pass  into  high-grade  subbituminous  and  bituminous  ones.  Red 
Lodge,  Carbon  County,  yielding  a  coal  between  bituminous  and  subbitumi- 


COAL 


45 


nous,  is  the  most  important  producer,  and  the  Bull  Mountain  area  is  now 
second.     Coking  bituminous  coal  is  also  obtained. 


Areas  with 
workable  bituminous 
and  some  anthracite 


Possible  areas  of 

workable 
subbituminous  coals 


Areas  probably  containing 
subbituminous  coal 
under  heavy  cover 


Areas  with 

workable 

eubbituminous 


FIG.  19.  —  Map  showing  distribution  of  different  kinds  of  coal  in  Wyoming.     (After 
Parker,  U.  S.  Geol.  Sure.,  Min.  Res.,  1910.) 

Gulf  Province  Lignites  (70,  73,  105-107).  —  These  are  of  Eocene 
(Tertiary)  age  and  are  all  low  grade,  with  the  exception  of  those 
along  the  Rio  Grande,  northwest  of  Laredo,  which  may  be  re- 
garded as  subbituminous.  Those  found  near  Eagle  Pass  are 
of  still  better  quality,  but  occur  in  the  Cretaceous. 

Pacific  Coast  Fields  (37).  — Tertiary  coals,  partly  bituminous, 
though  mainly  lignitic,  occur  scattered  over  a  wide  area  in  the  states 
of  California  (50-53),  Washington  (114),  and  Oregon  (93,  94).  The 
separate  fields  are  limited  in  extent,  and  widely  separated. 
Their  output  is  small  as  compared  with  some  other  states,  but 
still  it  is  becoming  of  growing  importance. 

Of  the  scattered  fields  in  Washington,  the  most  important  lie 
directly  east  of  Seattle  and  Tacoma.  The  total  thickness  of 


46 


ECONOMIC  GEOLOGY 


coal-bearing  strata  is  about  10,000  feet, 
but  important  coal  beds  are  found 
only  in  the  lower  2000  feet.  The 
quality  of  the  coal  varies  with  the  extent 
of  the  dynamic  disturbance,  and  hence 
there  may  be  variation  even  in  a  single 
field.  Some  of  the  coal  is  coking.  The 
industry  suffers,  however,  from  compe- 
tition with  oil  fuel. 

Both  California  and  Oregon  are  small 
producers.  In  the  former  coals  of  sub- 
^bituminous  character  have  been  mined 
near  Tesla,  Alameda  County,  and  re- 
cently coal  of  good  bituminous  grade 
has  been  worked  in  Stone  Canyon, 
Monterey  County.  Indeed  this  is  of 
sufficiently  high  quality  to  compete  with 
foreign  coals  brought  into  San  Francisco. 

In  Oregon,  the  Coos  Bay  field  has 
been  a  small  but  fairly  steady  producer. 

Oil  may  be  said  to  dominate  the  fuel 
situation  along  the  Pacific  coast,  and  as 
long  as  this  continues,  the  demand  for 
coal  will  be  limited. 

Alaska  (45,  46) .  —  Although  Alaskan 
coal  was  first  mined  in  1852  at  Port 
Graham,  and  coal  deposits  have  been 
discovered  at  a  number  of  localities, 
the  quantity  produced  is  small.  This 
is  due  to  location  (Fig.  21),  character 
of  deposits,  which  are  often  badly 
folded  and  crushed,  cheaper  oil  fuel, 
and  also  conditions  obtaining  as  relat- 
ing to  patent  claims  regulated  by  the 
U.  S.  Government.  These  last  named 
obstacles  have  no  been  largely  re- 
moved and  developments  are  expected 
to  follow  the  building  of  railroads 
which  will  render  the  fields  acces- 
sible.1 Indeed,  in  1913,  the  domestic 

lBur.  Mines,  Bull.  36,  1912. 


COAL 


47 


product    formed    only    1.7  per    cent    of  all    the    coal   used   in 
Alaska. 

The  table  on  p.  48  gives  the  character  and  location  of  the 
Alaskan  coals. 


FIG.  21. — Map  of  Alaska,  showing  distribution  of  coal  and  coal-bearing  rocks,  so 
far  as  known.     (After  Martin,  U.  S.  Geol.  Surv.,  Bull.  314.) 

Canada.  —  The  coal  regions  of  Canada  include:  (1)  The 
Maritime  Provinces;  (2)  Western  Provinces;  (3)  Vancouver 
and  other  Pacific  Coast  islands. 

Maritime  Provinces.  —  Leaving  out  the  coals  of  New  Bruns- 
wick, which  are  of  little  importance,  we  have  several  areas 
of  active  production  in  Nova  Scotia.  There  the  coal-bearing 
rocks  range  from  Lower  Carboniferous  to  possibly  Permian, 
but  the  only  important  beds  are  those  occurring  in  the  Coal- 
Measures  proper,  lying  above  the  Millstone  Grit.  The  four 
areas  are  (1)  the  Cumberland  (including  Joggins  and  Spring 
Hill),  (2)  Pictou,  (3)  Inverness,  and  (4)  Sydney.  In  all  of  these, 
the  coal  is  bituminous,  and  in  (2)  and  (4)  of  coking  character. 
The  beds  show  more  or  less  folding,  and  in  one  area  at  least- 
(Pictou)  some  strong  faulting.  It  is  interesting  to  note  that  ia 


48 


ECONOMIC  GEOLOGY 


KIND  AND  DISTRIBUTION  OF  ALASKA  COALS 


SYSTEM 

SERIES 

CHARACTER  OF  COAL 

PRINCIPAL  DISTRIBUTION 

Quaternary 

Pleistocene 

Lignitic 

Yukon  basin  and  other 

parts  of  Alaska. 

Pliocene 

Lignitic 

Yakutat  Bay  and  other 

localities. 

Tertiary 

Miocene   or 
Eocene 

Anthracitic    and 
bituminous 

Bering  River 

Eocene 

Chiefly     lignitic; 

Throughout    Alaska, 

also  some  bitu- 

notably on  Cook  Inlet 

minous  and  sub- 

and     in     Matanuska 

bituminous. 

Valley,    and    Yukon 

basin. 

Cretaceous 

Upper  Cretaceous 

Subbituminous 

Alaska  peninsula,   Yu- 

and bituminous 

kon      and      Colville 

basins. 

Jurassic 

Lignitic,  subbitu- 

Near     Cape     Lisburne 

minous,  and  bi- 

and    in     Matanuska 

tuminous 

Valley. 

Carboniferous 

/  Pennsylvanian 
I  Mississiopian 

Subbituminous 
Bituminous 

Yukon  River. 
Twenty  miles  south  of 

Cape  Lisburne. 

the  Pictou  area,  the  upper  and  lower  series  of  seams  are  separated 
by  oil  shales. 

Western 


alif'ax 


Provinces.  - 

Coal-bearing  rocks  of  Cre- 
taceous, and  to  a  lesser  ex- 
tent Tertiary  age  are  widely 
distributed  throughout  the 
western  provinces. 

Within  the  Great  Plains 
regions  the  beds  lie  fairly 
flat,  and  the  coals  are.  either 
lignite  or  Subbituminous  but 
along  the  foothills  and  in 
the  mountains  themselves 
the  coal-measures  are  folded 

and  faulted,  the  sediments  usually  more   consolidated,  and  the 

coals  of  a  higher  grade  ranging  from  bituminous  to  anthracite. 
Some  of  the  areas  are  actively  worked  at  several  points,  but 

there  still  remain  undeveloped  districts,  awaiting  a  market  and 

transportation  facilities. 


FIG.  22.  —  Map  showing  coal  areas  of 
Nova  Scotia.  (After  Bowling,  Can. 
GcoL  Surv.,Mem.  59.) 


COAL 


49 


Saskatchewan.  —  Lignite-bearing  Tertiary  rocks  cover  a  wide 
extent  of  territory  in  the  southern  part  of  the  province,  and  a 
number  of  beds  are  known,  which  are  worked  chiefly  in  the 


SCALE  OF  MILES 


FIG.  23.  —  Map  showing  coal  areas  of  Western  Canada.     (After  Dowling,  Can- 
Geol.  Surv.,  Mem.  59.) 


50  ECONOMIC  GEOLOGY 

Souris  field.  (Fig.  23.)  The  Cretaceous  coals  of  the  Belly 
River  series  are  as  yet  unimportant. 

Alberta.  —  Coal  is  found  at  three  horizons  of  the  Cretaceous, 
viz.,  Edmonton  and  part  of  Paskapoo,  Belly  River  and  Kootenay. 
The  Edmonton  coals  lie  in  a  great  syncline,  with  the  Paskapoo 
sandstone  forming  the  upper  beds  in  the  center.  The  beds 
of  the  eastern  limb  have  a  lower  dip  than  those  of  the  western 
cne  towards  the  mountains,  so  that  the  coals  change  from  lignites 
in  the  northeastern  part  to  coking  coals  in  the  foothills.  Ed- 
monton is  the  chief  mining  center. 

The  Belly  River  coal  series,  which  covers  about  16,000  square 
miles  in  central  and  southern  Alberta,  carries  coals  ranging 
from  lignites  near  Medicine  Hat  to  subbituminous  coals  around 
Lethbridge,  but  the  series  traced  to  the  foothills  also  carries 
coking  coals. 

The  coal  of  the  Kootenay  formation  lies  deeply  buried  under 
the  Plains,  but  in  the  Rocky  Mountains  it  is  exposed  at  a  num- 
ber of  points  in  uplifted  fault  blocks,  and  along  the  crests  of 
anticlines.  Some  is  also  found  in  synclinal  troughs.  The  Al- 
berta areas  are  known  both  in  the  outer  ranges  and  in  the  foot- 
hills from  near  the  international  boundary  to  beyond  the  Atha- 
basca River.  The  coals  are  generally  bituminous,  sometimes  of 
coking  character,  but  semianthracite  and  anthracite  beds  are 
also  known.  The  bituminous  type  is  actively  worked  in  the 
Crows  Nest  Pass  district  at  Coleman  and  Frank,  while  the 
anthracite  is  mined  in  the  vicinity  of  Canmore  and  Banff. 

British  Columbia.  —  On  the  mainland,  the  coal  areas,  which 
are  more  or  less  isolated,  are  chiefly  of  Lower  Cretaceous  age, 
and  of  bituminous  character,  although  sometimes  locally  altered 
to  anthracite.  An  important  basin  is  situated  in  the  western 
part  of  the  Crows  Nest  Pass,  where  the  section,  sometimes 
showing  3700  feet  of  measures,  may  carry  over  20  beds,  exceed- 
ing 1  foot  in  thickness.  Scattered  deposits  of  Tertiary  coal 
are  also  known,  and  worked  specially  around  Princeton  and  in 
the  Nicola  Valley.  These  have  been  partly  covered  by  igneous 
flows,  and  locally  altered  to  bituminous  coal. 

Vancouver  Island.  —  The  coals,  so  far  as  known,  are  of  Upper 
Cretaceous  age,  associated  with  the  thick  Nanaimo  series  of 
clastic  sediments.  A  variable  degree  of  folding  and  some  fault- 
ing occurs,  and  the  seams  lack  persistence.  Some  of  the  bitu- 
minous coals  are  coking. 


PLATE  IX 


FIG.  1.  —  Beds  of  subbituminous  coal  near  Estevan,  Sask.     (H.  Ries,  photo.) 


FIG.  2.  — Coke  ovens  and  tipple  at  Coleman,  Alberta;    Crows  Nest  Pass  field. 

(H.  Ries,  photo.) 

(51) 


52  ECONOMIC  GEOLOGY 

Yukon.  —  Lignites  of  Tertiary,  and  lignites  to  anthracites  of 
Jura-Cretaceous  age  are  known. 

Other  Foreign  Fields.  —  Europe  contains  extensive  deposits  of  coal,  the 
bituminous  and  anthracite  varieties  being  chiefly  of  Upper  Carboniferous 
age,  although  important  Lower  Carboniferous  deposits  are  known  in  Central 
Russia  and  Scotland.  Of  the  Upper  Carboniferous  or  Coal  Measures 
proper,  there  are  important  deposits  in  western  Germany,  Belgium,  Northern 
France,  and  Great  Britain.  They  are  mostly  bituminous,  and  may -show 
strong  folding  and  faulting.  Anthracite  is  mined  in  Wales  and  Russia. 

The  lower  grades  of  coal  chiefly  of  Tertiary  age,  are  an  important  source 
of  supply  in  southern  Russia,  as  well  as  in  Austria,  Germany,  and  to  a 
lesser  extent  France. 

Asia  contains  extensive  areas  of  Permo-Carboniferous  coals  in  China 
(anthracite  to  lignite),  as  well  as  India,  while  Tertiary  coals  are  an  important 
source  of  supply  in  Japan  (bituminous)  and  northeast  Siberia. 

Australia  contains  both  Carboniferous  and  Tertiary  coals,  the  former 
being  especially  important  in  New  South  Wales.  In  South  America  the 
best  grades  of  coal  appear  to  be  those  along  the  Pacific  and  Gulf  of  Mexico 
in  formations  of  Tertiary  age,  while  in  Africa,  the  important  deposits — of 
Carboniferous  to  Jurassic  age — are  confined  to  the  southern  part  of  the 
continent. 

In  Mexico  the  most  important  fields  are  Cretaceous  ones  of  bituminous 
character,  near  the  Texas  border,  on  the  Rio  Grande  and  its  tributaries. 

The  Philippine  coals  are  of  Tertiarjr  age,  and  range  from  lignite  to  bitu- 
minous, but  the  area  known  to  be  underlain  by  mineable  coal  does  not 
cover  more  than  7  square  miles. 

Estimated  Coal  Reserves  of  the  World.  —  Much  attention  has  been 
given  in  recent  years  to  the  necessity  of  conserving  the  coal  supply,  and  in 
this  connection  the  figures  given  on  p.  53  and  collected  by  the  executive  com- 
mittee of  the  International  Geological  Congress  of  1913,  *  are  of  interest. 
They  include  both  the  actual  and  probable  reserves,  and  have  been  classified 
according  to  kinds  of  coal  as  follows: — 

A.  Coals  with  large  percentages  of  fixed  carbon,  including,  besides  the 
anthracites,  the  dry,  non-coking  coals  that  burn  with  a  short  flame. 

B  and  C.  Bituminous  coals,  including  some  of  the  non-coking,  but  free- 
burning  coals,  and  the  coking  coals  burning  with  a  long  flame.  The  cannel 
coals  and  coals  with  very  high  volatile  are  under  C. 

D.  Subbituminous  coals,  and  the  lignites. 

Production  of  Coal.  —  The  first  mention  of  coal  in  the  United 
States  is  probably  in  the  journal  of  Father  Hennepin,  who  in 
1679  recorded  the  site  of  a  "  cole  mine  "  on  the  Illinois  River 
near  the  present  city  of  Ottawa,  Illinois,  but  the  first  actual 
mining  appears  to  have  occurred  in  the  Richmond  basin,  Virginia, 
about  seventy  years  later.  The  first  records  of  production  are 

i  The  Coal  Resources  of  the  World.  Vols.  I,  II,  III  and  Atlas.  Morang  &  Co., 
Ltd.,  Toronto,  1913, 


COAL  53 

COAL  RESERVES  OF  THE  WORLD  (IN  MILLION  TONS) 


CLASS  OF  COAL 

TOTALS 

A 

B  and  C 

D 

ANTHRA- 

CITIC 

COALS 

BITUMINOUS 
COALS 

STTBBITUMI- 

NOUS    AND 

LIGNITES 

United  States 
Eastern  fields  .     . 
Interior  fields  . 
Gulf  fields   .     .     . 
Northern  plains    . 
Mountains     and 
coast   .     .     .     . 
Coal    deeply    cov- 
ered    .... 

16,906 
363 

494,454 
478,232 

511,360 
478,595 
20,952 
1,175,106 

1,028,151 

804,900 
19,593 

3,838,657,« 
500 

1,234,269 

20,952 
1,134,000 

692,207 
16,293 

484 

41,106 
335,460 

604,900 
1,369 

Alaska     .... 

Canada 
Newfoundland. 
Nova  Scotia     .     . 
New  Brunswick    . 
Ontario  .     .     .     . 
Manitoba    . 
Saskatchewan  .     . 
Alberta  .... 
British  Columbia  . 
Yukon    .... 
N.  W.  Territories. 
Arctic  Islands 

1,931 

19,684 

1,955,521 
500 
9,719 
151 

1,863,452 

9,719 
151 
25 
160 
57,400 
1,075,039 
76,035 
4,940 
4,800 



25 
160 
57,400 
876,179 
5,196 
4,690 
4,800 

768 
1,350 
40 

198,092 
69,489 
210 

6,000 

U.  S.  and  Can.     . 
South  America.     , 
Europe    .... 
Asia    . 

2,158 

283,661 

948,450 



21,842 
700 
54,346 
407,637 
659 
11,662 

2,239,182 
31,397 
693,162 
760,098 
133,481 
45,123 

2,811,902 



5,073,426 
32,097 
784,190 
1,279,586 
170,410 
57,839 

36,682 
111,851 
36,270 
1,054 

Oceania  .     .     .     . 
Africa      .     . 

World  total.     .     . 



7,397,548 

in  1822.  Ohio  probably  ranks  second  in  priority  of  production, 
as  coal  was  discovered  there  in  1755,  but  the  records  of  mining 
date  only  to  1838.  The  mining  of  Pennsylvania  anthracite  began 


54 


ECONOMIC   GEOLOGY 


in  1790,  and  in  1807,  55  tons  were  shipped  to  Columbus,  Ohio. 
The  regular  production  dates  from  1814.1 

The  phenomenal  growth  of  the  coal  mining  industry  is  well 
shown  by  the  diagram  (Fig.  24). 

The  production  of  the  individual  states  since  1910  is  given  on 
page  55. 

Grouping  the  output  by  regions,  the  overwhelming  importance 
of  the  Appalachian  region  is  well  seen. 

PRODUCTION  OF  COAL  IN  UNITED   STATES  BY  REGIONS  FROM   1910-1914 

IN  SHORT  TONS 


1910 

1911 

1912 

1913 

1914 

Anthracite  (Pa.,    .      . 

84,485,236 

90,464,067 
120 

84,361,598 
200 

91,524,922 

90,821,507 

Appalachian 
Northern       .... 
Eastern    

287,816,446 
1,534,967 
72,634,356 

275,212,234 
1,476,074 
75,041,014 

307,410,102 
1,206,230 
83,044,272 

330,737,079 
1,231,786 
87,302,055 

284,813,462 
1,283,030 
82,129,925 

Western     and     South- 
western    .... 
Rocky    Mountain    and 
and   Northern  Great 
Plains  
Pacific     Coast     and 
Alaska       .... 

22,276,364 

28,857,413 
3,991,596 

24,502,107 

26,044,387 
3,631,123 

26,580,416 

28,449,860 
3,413,902 

27,875,292 

27,338,220 
3,950,865 

26,396,916 

24,952,567 
3,128,070 

a.  Va.  production  included  in  Appalachian  region. 

Price  per  Ton.  —  The  average  price  per  short  ton  of  coal  fluctu- 
ates somewhat  from  year  to  year,  and  yet  not  as  much  as  one  might 
imagine.  The  figures  below  show  the  prices  for  the  last  ten  years. 

AVERAGE  PRICE  PER  SHORT  TON  OF  COAL  IN  THE  UNITED  STATES  SINCE  1C03 


YEAR 

ANTHRA- 
CITE 

BITUMI- 
NOUS 

YEAR 

ANTHRA- 
CITE 

BITUMI- 
NOUS 

1903  .... 

$2.04 

$1.24 

1909       .      .      . 

SI.  84 

$1.07 

1904  .... 

1.90 

1.10 

1910     .     .     . 

1.90 

1.12 

1905  .... 

1.83 

1.06 

1911      .     .     . 

1.94 

1.11 

1906  .... 

1.85 

1.11 

1912     .     .     . 

2.11 

1.15 

1907  .... 

1.91 

1.14 

1913     .     .     . 

2.13 

1.18 

1908  .... 

1.90 

1.12 

1914     .     .     . 

2.07 

1.17 

Exports  and  Imports.  —  The  exports  consist  of  anthracite  and 
bituminous  coal,  the  quantity  of  bituminous  being  the  greater 
in  the  last  few  years.  They  are  made  principally  by  rail  over 
the  international  bridges  and  by  lake  and  sea  to  the  Canadian 

i  Parker,  E.  W.,  Min.  Res.  U.  S.  Geol.  Surv.,  1908. 


COAL 


55 


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56 


ECONOMIC   GEOLOGY 


provinces.  Exports  are  also  made  by  sea  to  the  West  Indies, 
to  Central  and  South  America  and  elsewhere. 

The  imports  are  principally  from  Australia  and  British 
Columbia  to  San  Francisco,  from  Great  Britain  to  the  Atlantic 
and  Pacific  coasts,  and  from  Nova  Scotia  to  Atlantic  coast  points. 

The  statistics  since  1909  are  given  below: — 


COAL  OF  DOMESTIC    PRODUCTION  EXPORTED  FROM   THE    UNITED  STATES 
1909-1914,  IN  LONG  TONS 


YEAR 

ANTHRACITE 

BITUMINOUS  AND  SHALE 

Quantity 

Value 

Quantity 

Value 

1909          .... 

2,842,714 
3,021,627 
3,553,999 
3,688,789 
4,154,386 
3,830,244 

$14,141,468 
14,785,387 
18,093,285 
19,425,263 
21,959,850 
20,211,072 

9,693,843 
10,784,239 
13,878,754 
14,459,978 
17,986,757 
13,801,850 

$24,300,050 
26,685,405 
34,499,989 
36,817,633 
45,449,664 
34,104,903 

1910  ...     .     . 
1911   .fei,     .     .     . 
1912 

1913 

1914 

COAL  IMPORTED  AND  ENTERED  FOR  CONSUMPTION  IN  THE  UNITED  STATES. 
1909-1914,  IN  LONG  TONS 


YEAR 

ANTHRACITE 

BITUMINOUS  AND  SHAT.E 

Quantity 

Value    „ 

Quantity 

Value 

1909 

3,191 

8,196 
,      2,463 
'  i-  1,670 
896 
15,800 

$12,918 
42,244 
12,550 
,  8,329, 
5,620 
25,380 

,274,903 
,986,258 
,234,998 
1  1,605,873 
1  1,412,997 
,380,204 

$3,628,533 
4,761,223 
3,604,797 
4,509,066 
3,853,930 
3,902,881 

1910  

1911    .      ."•  .      .      . 

1912  ... 

1913 

1914 

i  Includes  455,587  long  tons  of  slack  or  "culm  (value  $901,051)  passing  \  inch 
screen  in  1912;  352,007  tons  (value  $689,864)  in  1913;  and  164,672  tons  (value 
$303,348)  in  1914. 


COAL  57 

PRODUCTION  OF  COAL  IN  CANADA,  1912-1913,  BY  PROVINCES 


1913 

1914 

TONS 

VALUE 

TONS 

VALUE 

Nova  Scotia 

7,980,073 
2,714,420 
4,014,755 
212,897 
70,311 
19,722 

$17,812,663 
8,482,562 
10,418,941 
358,192 
166,637 
56,945 

7,338,790 
2,238,339 
3,667,816 
232,541 
104,055 
13,443 

$16,381,228 
6,994,810 
9,367,602 
375,438 
260,270 
53,760 

British  Columbia 
Alberta 

Saskatchewan       .     .  '  /. 
New  Brunswick    .     .     . 
Yukon  Territory       .     . 

Total 

15,012,178 

$37,334,940 

13,594,984 

$33,433,108 

The  Canadian  exports  in  1914  amounted  to  1,423,126  tons, 
valued  at  $3,880,175.  The  imports  for  1914  were  14,721,057  tons, 
valued  at  $39,801,498. 


STATISTICS  OF  THE  MANUFACTURE  OF  COKE  IN  THE  UNITED  STATES  IN 
1880,  1890,  1900,  1910-1914 


YEAR 

ESTAB- 
LISH- 
MENTS 

OVENS 

COAL 
USED 
(SHORT 
TONS) 

PER- 
CENTAGE 
YIELD 
OF  COAL 
IN  COKE 

COKE  PRO- 
DUCED 
(SHORT 
TONS) 

TOTAL 
VALUE  OF 
COKE  AT 
OVENS 

VALUE 

OFCOKE 

AT 

OVENS 

PER 

TON 

BUILT 

BUILD- 
ING 

1880 

186 

12,372 

1159 

5,237,741 

63.0 

3,338,300 

$  6,631,267 

$1.99 

1890 

253 

37,158 

1547 

18,005,209 

64.0 

11,508,021 

23,215,302 

2.02 

1900 

396 

58,484 

5804 

32,113,553 

63.9 

20,533,348 

47,443,331 

2.31 

1910 

578 

104,440 

2567 

63,088,327 

66.1 

41,708,810 

99,742,701 

2.39 

1911 

570 

103,879 

2254 

53,278,248 

66.7 

35,551,489 

84,130,849 

2.37 

1912 

559 

102,230 

2783 

65,577,862 

67.1 

43,983,599 

111,805,113 

2.54 

1913 

551 

102,650 

1321 

69,239,190 

66.9 

46,299,530 

128,922,273 

2.78 

1914 

536 

99,755 

1249 

51,623,750 

66.9 

34,555,914 

88,334,217 

2.56 

The  quantity  of  coal  consumed  in  manufacture  of  coke  in  1914 
was  51,623,750  short  tons,  valued  at  $74,949,565,  while  the  value 
of  the  coke  made  therefrom  was  $128,922,273. 

There  were,  in  1914,  536  establishments,  operating  99,755 
ovens. 

There  were  5809  by-product  ovens  in  1914  with  644  build- 
ing. 

Of  the  1914  production  32.47  per  cent  of  the  quantity  and  43.11 
per  cent  of  the  value  was  from  by-product  ovens. 


ECONOMIC  GEOLOGY 


FIG.  24. — Curve  showing  relation  of  increase  in  population  in  the  United  States 
to  production  of  coal,  1856-1914.     (U.  S.  Geol.  Surv.,  Min.  Res.  1914.) 


COAL 


59 


VALUE  OF  PRODUCTS  OBTAINED  IN   MANUFACTURE  OF    COKE  IN  RETORT 
OVENS  IN  1913  AND  1914 


1913 

1914 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

Gas 

M  cubic  feet 
gallons 
reduced    to 
pounds 
gallons 
pounds 

64,553,941 
115,145,025 

173,342,349 
4,102,448 
128,663,936 

12,714,700 

$5,694,691 
2,830,158 

5,324,444 
537,413 
12,135,656 
403,579 
16,925,941 
48,637,852 

61,364,375 
109,901,315 

170,763,906 
5,938,223 
1  25,370,509 

11,219,943 

$6,009,583 
2,867,274 

4,696,590 
658,497 
12,300,137 
2  997,007 
17,529,088 
38,080,167 

Tar  
Ammonia,    sulphate    or 
equivalent  in  sulphate 
Ammonia  liquor 
Anhydrous  ammonia    . 
Other  by-products  . 

Total  value  of  by-products    . 
Coke      short  tons 

Grand  total     . 



65,563,793 



55,609,255 

1  Mainly  ammoniacal  liquor  sold  on  pound  basis  of  NH3. 

2  Mainly  benzol. 


World's  Production.  —  The  following  figures  are  those  given  by 
the  U.  S.  Geol.  Survey,  and  compiled  from  various  sources: — 


THE  WORLD'S  PRODUCTION  OF  COAL,  IN  SHORT  TONS 


COUNTRY 

PRODUCTION 

COUNTRY 

PRODUCTION 

United  States  (1914)  .     . 
Great  Britain  (1914)  .     . 
Germany  (1914) 

513,525,477 
297,698,617 
270  594  952 

Dutch  East  Indies  (1913) 
Indo-China  (1912).     .     . 
Servia  (1912) 

453,136 
471,259 
335  000 

Austria-Hungary  (1913)  . 
France  (1913)     .           .     . 
Russia  (1913)     .           .     . 
Belgium  (1913)             .     . 
Japan  (1914)      .           .     . 
India  (1913)        .           .     . 
China  (1913)      .           .     . 
Canada  (1914)  .           .     . 
New  South  Wales  (1914) 
Transvaal  (1913)          .     . 
Spain  (1913)       .           .     . 
Natal  (1913) 

59,647,957 
45,108,544 
35,500,674 
25,196,869 
21,700,572 
18,163,856 
i  15,432,200 
13,597,982 
11,644,476 
5,225,036 
4,731,647 
2  898,726 

Sweden  (1913)   .... 
Western  Australia  (1913)  . 
Peru  (1913)   .     .     . 
Formosa  (1912)       . 
Bulgaria  (1912).      . 
Rhodesia  (1913)      . 
Roumania  (1911)    . 
Cape  Colony  (Cape  of  Good 
Hope)  (1913)    .     . 
Korea  (1911)      .     . 
Tasmania  (1914)     . 
British  Borneo  (1913) 

401,199 
351,687 
301,970 
306,941 
324,511 
237,728 
266,784 

67,481 
138,508 
68,130 
49,762 

New  Zealand  (1913)    .     . 
Holland  (1913)  .... 
Chile  (1913)  
Queensland  (1914)       .     . 
Mexico  (1912)    .... 
Bosnia   and  Herzegovina 
(1913) 

2,115,834 
2,064,608 
1,362,334 
1,180,825 
982,396 

927  244 

Spitzbergen  (1911). 
Brazil  (1911)      .     . 
Portugal  (1913)       . 
Venezuela  (1913)    . 
Switzerland  (1911). 
Philippine  Islands  (1912) 
Unspecified    

44,092 
16,535 
27,653 
13,355 
8,267 
2,998 
i  1,016,947 

Italy  (1913) 

772  802 

Total     

«  1,346,000,000 

Victoria  (1912)  .... 
Orange  Free  State  (Orange 
River  Colony  (1913). 

668.524 
609,973 

l  Estimated. 


2  Approximate. 


60 


ECONOMIC  GEOLOGY 


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COAL  61 

PEAT 

Origin.  —  So  much  attention  has  been  attracted  to  this  material 
in  the  last  few  years  that  it  seems  desirable  to  treat  it  as  a  separate 
topic,  and  partly  so  because  it  can  be  used  for  other  purposes  than 
fuel. 

Peat  (128)  may  be  defined  as  "  vegetable  matter  in  a  partly  de- 
composed and  more  or  less  disintegrated  condition,"  and  represents 
much  of  the  "dark-colored  or  nearly  black  soil  found  in  bogs  and 
swamps."1  The  dry  peat  may  be  very  fibrous  and  light  colored, 
or  compact,  structureless,  and  dark  brown  or  black.  If  wet,  it 
contains  as  much  as  89  to  91  per  cent  or  even  more  water.  As 
previously  mentioned  (p.  1)  it  is  produced  by  the  slow  decay,  under 
water,  of  accumulated  plant  remains. 


FIG.  25. —  Diagram  showing  how  plants 'fill  depressions  from  the  sides  and  top,  to 
form  a  peat  deposit.  —  1.  Zone  of  Chara  and  floating  aquatics.  2.  Zone  of 
Potamogetons.  3.  Zone  of  water  lilies.  4.  Floating  sedge  mat.  5.  Advance 
plants  of  conifers  and  shrubs.  6.  Shrub  and  Sphagnum  zone.  7.  Zone  of  Tam- 
arack and  Spruce.  8.  Marginal  Fosse.  (After  Davis,  Mich.  Geol.  Surv.,  Ann. 
Rept.  for  1906.) 

The  two  essential  conditions  for  peat  formation  are  (1)  restricted 
access  of  air  to  impede  growth  of  decay-producing  organisms,  and 
(2)  abundance  of  water  to  permit  profuse  plant  growth. 

This  decay  is  accomplished  mainly  through  the  agency  of  fungi 
and  air-requiring  bacteria  which  break  down  the  tissues,  the  decay 
involving  decrease  in  bulk,  darkening  in  color,  and  liberation  of 
gaseous  constituents.  Both  moisture. and  air  are  essentials  to  this 
process. 

Since  an  abundance  of  water  is  essential  to  peat  formation,  and 
as  it  is  formed  by  accumulation  of  plants  in  the  spot  where  they 
grew,  it  requires  plants  of  a  water-loving  nature.  But  peat  may 
form  in  lakes  or  ponds,  or  in  moist  depressions  or  flat  areas,  and 
hence  plants  adapted  to  these  different  sets  of  conditions  being  differ- 

1  If  this  material  contains  too  much  mineral  matter  to  burn  freely,  it  is  technically 
known  as  muck. 


62  ECONOMIC  GEOLOGY 

ent,  it  follows  that  the  product  may  come  from  more  than  one 
kind. 

Peat  may  be  formed  in  lakes  or  similar  depressions  by  aquatic 
plants,  including  minute  algae,  building  up  a  deposit  from  the 
bottom  and  around  the  sides,  in  water  shallower  than  15  feet.  The 
extension  of  this  deposit  into  deeper  water  and  building  up  of  the 
bottom  permits  growth  of  aquatic  seed  plants,  resulting  in  estab- 
lishment of  characteristic  zones.  These  are  characterized  (127) 
by  (1)  the  pond  weeds,  Potamogeton,  next  to  the  deepest  water; 
(2)  shoreward  of  this  the  pond  lilies;  (3)  the  lake  bulrush,  Scirpus; 
and  (4)  the  amphibious  sedges,  especially  the  turf-forming  slender 
sedge.  In  some  localities  some  of  the  zones  may  be  absent.  The 
sedges  may  also  extend  outward  from  the  shore,  forming  a  floating 
mat,  which  may  cover  the  entire  surface  of  the  pond,  and  become 
covered  by  a  growth  of  shrubs  and  even  large  trees,  although  the 
mat  may  not  be  more  than  4  or  5  feet  thick. 

Peat  may  also  form  on  moist,  flat,  or  sloping  surfaces,  in  depres- 
sions from  which  standing  water  is  naturally  absent,  provided  the 
plant  remains  are  kept  saturated  with  water,  which  they  hold  there 
partly  by  capillarity.  In  such  situation  plants  of  the  rush,  grass, 
sedge  type,  or  sphagnum  are  important.  This  type  of  peat  accumu- 
lation flourishes  best  in  regions  of  heavy  rainfall  and  moist  atmos- 
phere, and  the  deposit  'shows  an  irregularly  stratified  structure, 
but  more  uniform  character  than  the  filled-basin  type  first  described, 
whose  structure  is  more  uniform  below  the  original  water  level,  but 
whose  upper  3-5  feet  is  nearly  always  of  different  structure  and  com- 
position from  that  below.  Some  bogs  may  be  of  composite  origin. 

The  present  surface  vegetation  of  the  bog  does  not  necessarily 
indicate  the  kind  of  plant  from  which  the  peat  was  formed. 

An  interesting  type  of  peat  is  that  found  in  salt  marshes,  of  which 
there  are  thousands  of  acres  along  the  Atlantic  coast,  these  marshes 
being  poorly-drained  plains  subject  to  frequent  overflow  by  the  sea- 
water.  Studies  by  Davis  of  the  Maine  marshes  (128)  indicate  that 
the  peat  is  either  of  "  fresh- water  origin  below  a  relatively  thin 
stratum  of  salt-water  peat,  or  else  made  up  entirely  of  plants  similar 
to  those  growing  on  the  marshes  to-day  at  about  high  tide  level." 
The  suggested  explanation  is  that  the  fresh-water  peat  has  been 
formed  in  fresh-water  bogs  situated  on  a  slowly  sinking  coast,  while 
the  upper  or  salt-water  peat  formed  when  the  land  was  low  enough  to 
permit  an  influx  of  salt  water,  thus  permitting  the  growth  of  only 
such  plants  as  could  stand  it. 


COAL  63 

The  fresh-water  peat  may  be  of  fuel  value,  but  that  formed 
wholly  by  the  growth  of  salt-marsh  plants  is  too  full  of  fine  silt 
and  mud  tidal  deposits  to  be  of  marketable  character.  (See 
analyses,  p.  9.) 

Uses  of  Peat  (119,  126,  127).  —  The  main  use  of  peat  is  for  fuel, 
but  it  has  never  been  extensively  used  in  America  for  this  purpose. 
A  number  of  experimental  plants  have  been  built  in  Canada,  but 
most  of  them  have  not  been  successful  nor  have  any  been  so  in  the 
United  States.  The  failure  may  have  been  due  to  lack  of  capital, 
improper  machinery,  or  lack  of  experience.  Since  a  detailed  dis- 
cussion of  peat-fuel  technology  is  beyond  the  limits  of  this  work, 
those  wishing  to  follow  it  up  are  referred  to  Nos.  126,  127,  128,  of 
the  bibliography. 

For  fuel  purposes  the  peat  may  be  used  in  air-dried  form  as  it 
comes  from  the  bog,  pressed  into  blocks  (machine  peat),  in  briquettes 
with  or  without  binder,  or  in  gas  producers.  There  is  only  one 
peat  briquetting  plant  in  Europe  (1913),  but  peat  powder  has 
been  successfully  used  in  special  burners.  Peat  fuel  has  been 
used  in  European  glass  factories. 

Of  importance  is  the  use  of  the  more  fibrous  kinds  of  peat  as 
a  material  for  bedding  for  stock  and  for  packing,  as  well  as  for 
deodorizing  and  disinfecting.  Those  varieties  of  powdered  peat 
which  are  rich  in  nitrogen  are  dried  and  sold  for  filler  in  certain 
kinds  of  artificial  fertilizer,  and  although  a  use  of  recent  origin 
it  seems  to  be  growing.  "  Mull  "  is  the  finer  matter  separated 
from  moss  litter  by  screening,  and  sold  for  deodorizing,  filtering, 
disinfecting,  and  packing  purposes. 

The  manufacture  of  fertilizer  filler  is  at  present  the  largest 
industry  based  on  peat  in  the  United  States. 

Those  peats  having  a  strong  fiber  can  be  used  in  the  manufacture 
of  cloth  and  paper,  but  there  is  only  one  American  plant  turning 
out  this  class  of  product.  Peat  can  also  be  utilized  for  making 
ethyl  alcohol,  and  also  for  pressing .  into  a  structural  material 
resembling  wood. 

Peat  baths  have  long  been  used  for  medicinal  purposes  in 
Germany  and  Austria,1  but  only  recently  have  they  been  tried 
in  the  United  States. 

Distribution  in  the  United  States.  —  Those  regions  possessing 
peat  beds  of  sufficient  size  and  depth  to  be  of  commercial  value 
lie  mostly  outside  of  the  coal-producing  territory. 

1  H.  Schreiber,  Moorkulturstation  in  Sebastiansberg,  Vol.  XII,  1910. 


64 


ECONOMIC  GEOLOGY 


Davis  states  that  workable  beds  are  found  in  many  states 
lying  north  of  the  Ohio  and  east  of  the  Missouri  rivers,  in  the 
coastal  portions  of  the  Middle  and  South  Atlantic  and  Gulf 
States,  and  in  the  narrow  strip  along  the  Pacific  coast  from 
southern  California  northward  to  the  Canadian  boundary. 

Production  of  Peat.  —  Few  statistics  showing  the  production 
of  peat  in  the  United  States  are  available. 

The  production  and  imports  for  1913  and  1914  are  given  by 
the  United  States  Geological  Survey  as  follows: 


PRODUCTION,  IMPORTS,  AND  CONSUMPTION  OF  PEAT  IN  THE  UNITED  STATES 
IN  1914,  IN  SHORT  TONS 


USE 

PRODUCTION                      IMPORTS 

CONSUMPTION 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

Fertilizer  filler. 
Fertilizer     .     . 
Fuel  .... 
Miscellaneous  l 
Peat  moss  litter 

Total  .     .     . 

22,767 

14,962 
1,925 
7,439 

$136,994 
112,905 
6,540 
53,253 

22,767 
14,962 
1,925 
7,439 
9,921 

$136,994 
112,905 
6,540 
53,253 
57,542 

9921 

$57,542 

47,093 

309,692 

9921 

57,542 

57,014 

367,234 

Only  1  producer  each  of  peat  for  stock  food,  mud  baths,  and  paper  pulp. 


PRODUCTION,  IMPORTS,  AND  CONSUMPTION  OF  PEAT  IN  THE  UNITED  STATES 
IN  1913,  IN  SHORT  TONS 


USE 

PRODUCTION 

IMPORTS 

CONSUMPTION 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

Fertilizer     .     . 
Stock  food  .     . 
Stable  litter     . 

Total  .     .     . 

28,460 
4,800 

$169,600 
27,600 

10,983 

$55,719 

28,460 
4,800 
10,983 

$169,600 
27,600 
55,719 

33,260 

197,200 

10,983 

55,719 

44,243 

252,919 

The  1913  production  of  peat  in  Canada  was  estimated  at 
2600  short  tons,  valued  at  $10,100,  and  came  from  Quebec  and 
Ontario. 


COAL  65 


REFERENCES    ON    COAL 

ORIGIN.  1.  Ashley,  Econ.  Geol.,  II:  34,  1907.  (Maximum  rate  of  deposi- 
tion.) la.  Arber,  Natural  History  of  Coal,  1911.  2.  Campbell,  Econ. 
Geol.,  I:  26,  1905.  (Origin.)  3.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  491: 
705,  1911.  4.  Bowling,  Can.  Min.  Inst.  Jour.,  XII,  1909  and  XIII: 
180,  1911.  (Chemical  changes  in  coal  formation.)  4a.  Jeffrey,  Jour. 
Geol.,  XXIII:  218,  1915.  (Origin.)  5.  Lesquereux,  2d  Geol.  Surv. 
Pa.,  Ann.  Kept.:  95,  1885.  (Origin.)  6.  Lyell,  Amer.  Jour.  Sci., 
CLV:  353,  1843.  (Upright  trees  in  coal.)  7.  Moffat,  Amer.  Inst. 
Min.  Engrs.,  Trans.  XV:  819,  1887.  (Change  of  mine  prop  to  coal.) 

8.  Potonie,  Klassifikation  und  Terminologie  der  rezenten  brennbaren 
Biolithe  und  ihrer  Lagerstatten.     Prussian  Geol.  Surv.,  Berlin,   1906. 

9.  Potonie,  Die  Entstehung  der  Steinkohle,  Berlin,   1907.     10.  Smith, 
Econ.  Geol.,  I:    581,   1905-1906.     (Discussion  of  Campbell's  theory.) 

II.  Stevenson,  Proc.  Amer.  Phil.  Soc.,  LII:    31,   1913.     (Formation  of 
coal    beds.)     lla.  Stutzer,    Kohle,    Berlin,     1914.     12.  White,    Econ. 
Geol.,    Ill:     292,    1908.     (Problems    in    coal   formation.)     12a.  White 
and  Thiessen,  Bur.  Mines,  Bull.  38,  1913.     (Origin  and  microstructure.) 

CLASSIFICATION.  13.  Campbell,  Econ.  Geol.,  Ill:  134,  1908.  14.  Camp- 
bell, Amer.  Inst.  Min.  Engrs.,  Trans.  XXXVI:  324,  1906.  14a.  Camp- 
bell, Econ.  Geol.,  VI:  562,  1911.  (Proximate  analysis.)  15.  Collier, 
U.  S.  Geol.  Surv.,  Bull.  218,  1903.  16.  Dowling,  Can.  Min.  Inst., 
Quart.  Bull.,  No.  1:  61,  1908.  17.  Frazer,  Amer.  Inst.  Min.  Engrs., 
Trans.  VI:  430.  18.  Grout,  Econ.  Geol.,  II:  225,  1907.  19.  Parr, 

III.  Geol.  Surv.,  Bull.  3,   1906.     20.  White,  U.  S.  Geol.  Surv.,  Bull. 
382,  1909. 

COMPOSITION,  STRUCTURE,  ETC.  21.  Bain,  Jour.  Geol.,  Ill:  646,  1895. 
(Structure  of  coal  basins.)  22.  Fieldner,  Bur.  Mines.,  Tech.  Pap.  76. 
(Sampling  and  analysis.)  23.  Campbell,  Econ.  Geol.,  Ill:  48,  1907. 
(Value  of  coal  mine  sampling.)  24.  Catlett,  Amer.  Inst.  Min.  Engrs., 
Trans.  XXX:  559,  1901.  (Coal  outcrops.)  24a.  Grout,  Econ.  Geol., 
VI:  449,  1911.  (Relation  of  texture  to  composition.)  246.  Jeffrey, 
Econ.  Geol.,  IX:  730,  1914.  (Composition  and  qualities.)  25.  Lesley, 
Manual  of  Coal  and  its  Topography,  Philadelphia,  1856.  26.  Lord  and 
others,  Bur.  Mines,  Bull.  22,  1913.  (Analyses,  texts,  etc.)  26a.  Porter 
and  Ovitz,  Bur.  Mines  Tech.  Pap.  16,  1912.  (Oxidation.)  27.  Parr  and 
Hamilton,  Econ.  Geol.,  II:  693,  1907.  (Weathering  of  coal.)  28. 
Pishel,  Econ.  Geol.,  Ill:  265,  1908.  (Test  for  coking  coal.)  28a. 
Somermeier,  Composition,  Analysis,  Utilization  and  Valuation.  New 
York.  29.  Much  general  information  in  the  special  coal  reports  of 
Iowa,  Kansas,  Indiana,  and  Ohio  Geological  Surveys. 

GENERAL  AREAL  REPORTS.  30.  Hayes,  U.  S.  Geol.  Surv.,  22d  Ann.  Rep., 
Ill:  7,  1902.  (U.  S.  coal  fields.)  31.  MacFarlane,  Coal  Regions  of 
America,  700  pp.,  3d  ed.,  1877,  New  York.  32.  Nicholls,  The  Story 
of  American  Coals,  1897  (Phila.).  33.  White,  U.  S.  Geol.  Surv.,  Bull. 
€5.  (Bituminous  field,  Pa.,  Ohio,  and  W.  Va.)  34.  Series  of  papers 
on  the  several  coal  fields  of  the  United  States,  in  U.  S.  Geol.  Surv., 
22d  Ann.  Rept.,  Ill:  11-571,  1902,  as  follows:  Ashley,  p.  271.  (East- 


66  ECONOMIC  GEOLOGY 

era  Interior.)  35.  Bain,  p.  339.  (Western  Interior.)  36.  Hayes,  p. 
233.  (Southern  Appalachians.)  37.  Smith,  p.  479.  (Pacific  coast.) 
38.  Storrs,  p.  421.  (Rocky  Mountain  field.)  39.  Stock,  p.  6.  (Pa. 
anthracite.)  40.  Taff,  p.  373.  (Southwestern.)  41.  White,  Camp- 
bell, and  Hazeltine,  p.  125.  (Northern  Appalachians.) — Alabama: 
42.  Butts,  U.  S.  Geol.  Surv.,  Bull.  316:  76,  1907.  (Cahaba  field.)  43. 
Gibson,  Ala.  Geol.  Surv.,  1895.  (Coosa  field.)  44.  McCalley,  Ala. 
Geol.  Surv.,  1900.  (Warrior  field.)  Also  brief  accounts  in  U.  S.  G.  S. 
Bulletins  260  and  285. —Alaska:  45.  Brooks,  U.  S.  Geol.  Surv.,  22d 
Ann.  Kept.,  Ill:  515,  1902.  46.  Martin,  Ibid.,  Bulls.,  314:  40,  1907, 
and  284:  18,  1906. —Arizona:  47.  Blake,  Amer.  Geol.,  XXI :  345,  1898. 
48.  Campbell,  U.  S.  Geol.  Surv.,  Bull.  225:  240,  1904.  (Deer  Creek 
field.)— Arkansas:  49.  Collier,  U.  S.  Geol.  Surv.,  Bull.  326,  1907.- 
California:  50.  Arnold,  Ibid.,  Bull.  285:  223,  1906.  (Mt.  Diablo  range.) 

51.  Campbell,  U.  S.  Geol.  Surv.,  Bull.  316:  435,  1907.     (Stone  Canyon.) 

52.  Smith,   U.   S.   Geol.   Surv.,   22d  Ann.   Kept.,   Ill:    479.     53.  Also 
county   reports   in    llth   Ann.   Kept.    Calif.    State   Mining   Bureau.  — 
Colorado:    54.  Storrs,   U.  S.  Geol.  Surv.,  22d  Ann.  Kept.,  Ill:    421, 
also  special  reports  of  U.  S.  Geol.  Surv.,  Bulls.  297  (Yampa  field),  316 
(Durango  field),  341  (N.  W.  Colo.).     55.  U.  S.  Geol.  Atlas,  Folio  No.  9. 
(Anthracite  —  Crested  Butte  area.)     55a.  U.  S.  Geol.  Surv.,  Bulls.  510 
and  471.  — Georgia:    56.  McCallie,  Ga.   Geol.    Surv.,  Bull.  12,   1904. 
(General.) — Illinois:    57.  Parr,    Grout,    and  others,    111.   Geol.   Surv., 
Bull.  4:    187,  1906;    also  Ibid.,  Bull.  8:    151,  1907,  and  Bull.  16:    177, 
1911.     58.  Ashley,   U.  S.   Geol.   Surv.,   22d  Ann.  Kept.,   Ill:    271.- 
Indiana:   59.  Ashley,  Ind.  Dept.  Geol.  and  Nat.  Res.,  23d  Ann.  Rept., 
1899,    and  33d  Ann.   Rept.,    1909.  —  Indian  Territory:    60.  Taff,    U. 
S.  Geol.  Surv.,  22d  Ann.  Rept.,  Ill:   367,  1902;   also  Ibid.,  Bull.,  260; 
382,  1905. —  Iowa:    61.  Bain,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  Ill: 
339.     62.  Hinds,  la.  Geol.  Surv.,  XIX:    1909.     (General.)  —  Kansas: 

63.  Haworth  and  Crane,  Kas.  Geol.  Surv.,  Ill:   13,  1898.  —Kentucky: 

64.  Norwood,    Ann.    Rept.,    Inspector   of    Mines,    1901-1902.     (Much 
general   information.)     65.  Moore,    Ky.    Geol.    Surv.,    Ser.    2,    IV,    pt. 
XI:  423.     (Eastern  border  and  Western  field.)     66.  Ashley  and  Glenn, 
U.  S.  Geol.  Surv.,  Prof.  Pap.  49,  1906.     (Cumberland  Gap  field.)     67. 
Crandall,  Ky.  Geol.  Surv.,  Bull.  4,  1905,  also  Hoenig,  Ibid.,  4th  ser., 
I:   79,  1913.     (Big  Sandy  Valley.)     68.  Stone,  U.  S.  Geol.  Surv.,  Bull. 
316:     42,    1907.     (Elkhorn    field.)     69.  For    analyses,    see    Ky.    Geol. 
Surv.,  new  series,  Chem.  Rept.,  etc.,  pts.  I,  II,   and  III.     69a.  Dil- 
worth,  Amer.  Inst.   Min.  Engrs.,  Bull.  62:    149,   1912.     (Black  Mtn. 
district.)     696.  Fohs,   Ky.   Geol.   Surv.,   Bull.    18,    1912. —Louisiana: 
70.  Harris,  Prelim.  Rept.  on  Geol.  of  La.  for  1899:    134.     (Lignite.) 
-Maryland:     71.  Clark,    Md.    Geol.    Surv.,    V,    1905.  —  Michigan: 
72.  Lane,  Mich.  Geol.  Surv.,  VIII,  pt.  2.  —  Mississippi:    73.  Brown, 
Miss.  Geol    Surv.,  Bull.  3,   1909;    also  Econ.  Geol.,  Ill:    219,   1908. 
(Lignite.) —  Missouri:    74.  Winslow,  Mo.  Geol.  Surv.,  1891:    19-226. 
74a.  Hinds,    Mo.    Bur.    Geol.    Mines,    2d   ser.   XI:     1912.     (General.) 
—  Montana:     75.  Rowe,    Univ.    of    Mont.,    Bull.    4.     (General.)     76. 

.       Weed,  Eng.  and  Min.  Jour.,  LIII:    520,  542,  and  LV:    197.     (Great 


COAL  67 

Falls  and  Rocky  Fork  fields.)  77.  Scattered  papers,  on  individual 
fields  in  Bulls.  225,  285,  316,  341,  356,  390,  471,  531,  and  541  of  U.  S. 
Geol.  Survey.  —  Nebraska:  78.  Barbour,  Neb.  Geol.  Surv.,  I:  198, 
1903. —  Nevada:  79.  Spurr,  U.  S.  Geol.  Surv.,  Bull.  225:  289,  1904. 
Hance,  Ibid.,  Bull.  513:  313,  1913.  (Coaldale.)  —  New  Mexico:  80. 
Johnson,  Sch.  of  M.  Quart.,  XXIV:  456.  (Cerrillos.)  81.  Schrader, 
U.  S.  Geol.  Surv.,  Bull.  285:  241,  1906.  (Durango-Gallup.)  Other 
papers  in  Ibid.,  Bulls.  225  (White  Mountain  region),  285  (Engle),  316 
(Durango-Gallup,  Sandoval  County,  Lincoln  County),  341  (Durango- 
Gallup),  471  (Tijeras),  541  (Sierra  Blanca).  82.  Storrs,  U.  S.  Geol. 
Surv.,  22d  Ann.  Kept.,  Ill:  415,  1902.  —  North  Carolina:  83.  Wood- 
worth,  U.  S.  Geol.  Surv.,  22d  Ann.  Kept.,  Ill:  31,  1902.  83a.  Stone, 
U.  S.  Geol.  Surv.,  Bull.  471:  137,  1912.  (Dan  River.)  —  North  Dakota: 
84.  Babcock,  N.  Dak.  Geol.  Surv.,  1st  Bien.  Rept.,  1901:  56.  85. 
Wilder,  Econ.  Geol.,  July-Aug.,  1906.  (Lignites.)  86.  Storrs,  U.  S. 
Geol.  Surv.,  22d  Ann.  Rept.,  Ill:  415,  1902.  87.  Leonard,  U.  S.  Geol. 
Surv.,  Bull.  285:  316,  1906.  (N.  Dak.  —  Mont,  lignite  area.)  88. 
Smith,  U.  S.  Geol.  Surv.,  Bull.  341:  15,  1908.  (Sentinel  Butte.)  89. 
Burchard,  Ibid.,  Bull.  225:  276,  1903.  (Missouri  Valley.)  Ibid., 
Bull.  471.  (Fort  Berthold),  Bull.  531  (Williston),  Bull.  575  (Standing 
Rock  and  Cheyenne  River  Reservation.)  —  Ohio:  90.  Orton,  Ohio 
Geol.  Surv.,  VII:  255.  91.  Lord,  Bownocker,  Somermeier,  Ohio  Geol. 
Surv.,  4th  ser.,  Bull.  9,  1908.  92.  White,  U.  S.  Geol.  Surv.,  Bull.  65, 
1891.  (Stratigraphy.)  —  Oklahoma:  See  Indian  Territory.  —  Oregon: 
93.  Smith,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  Ill:  473,  1902.  94. 
Diller,  Ibid.,  19th  Ann.  Rept.,  Ill:  309,  1899.  (Coos  Bay.)  94a. 
Lesher,  U.  S.  Geol.  Surv.,  Bull.  541:  399,  1914.  (Eden  Ridge.)  946. 
Diller,  Ibid.,  Bull.  546:  130,  1914.  (s.  w.  Ore.)  94c.  Williams, 
Min.  Res.  Ore.,  I,  No.  1:  28,  1914.  (Squaw  Creek  basin.)  Pennsyl- 
vania: 95.  d'Invilliers,  2d  Pa.  Geol.  Surv.,  Rept.,  1885  and  1886.  (Pitts- 
burg  region.)  96.  MacFarlane,  Coal  Regions  of  America,  3d  ed.,  New 
York,  1877.  97.  Report  MM  of  2d  Pa.  Geol.  Surv.  contains  many 
analyses;  see  also  county  reports  of  same  survey.  98.  Lesley,  Final 
Summary  Rept.,  Ill,  pts.  1  and  2.  (Stratigraphy.)  99.  Hice  and 
others,  Top.  and  Geol.  Surv.,  Pa.,  1906-1908:  218,  1908.  99a.  Gardner, 
Ibid.,  Rept.  10,  1913.  (Broad  Top  field.)  100.  Stock,  U.  S.  Geol. 
Surv.,  22d  Ann.  Rept.,  Ill:  61,  1902.  (Anthracite.)  101. .  White, 
Campbell,  Hazeltine,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  Ill:  125, 
1902.  (Bituminous.)  Numerous  references  to  coal  in  U.  S.  G.  S. 
bulletins  and  geologic  atlas  folios,  for  list  of  which  see  bibliography 
in  Min.  Res.,  1907. — Rhode  Island:  lOla.  Ashley,  U.  S.  Geol. 
Surv.,  Bull.  615,  1915.  —  South  Dakota:  102.  Todd,  S.  Dak.  Geol. 
Surv.,  Bull.  1:  159.  See  also  U.  S.  Geol.  Surv.  Bulls.  499  and  575. 
—  Tennessee:  103.  Hayes,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  Ill: 
227,  1902.  104.  Ashley  and  Glenn,  U.  S.  Geol.  Surv.,  Prof.  Pap.  49, 
1906.  (Cumberland  Gap.)  104a.  Ashley,  Resources  Tenn.,  I,  No. 
5;  Nelson,  Tenn.  Geol.  Surv.,  Bull.  5,  1911.  Many  brief  references 
in  U.  S.  G.  S.  Geologic  Atlas  folios.  —  Texas:  105.  Durable,  Bull,  on 
Lignite,  Tex.  Geol.  Surv.  106.  Phillips,  Univ.  Tex.  Min.  Surv.,  Bull. 


68  ECONOMIC  GEOLOGY 

3,  1902.  (Coal  and  lignite.)  106a.  Phillips,  Univ.  Tex.  Bull.  189, 
1911.  (Analyses.)  107.  Vaughan,  U.  S.  Geol.  Surv.,  Bull.  164,  1900. 
(Rio  Grande  fields.)  108.  Taff,  U.  S.  Geol.  Surv.,  22d  Ann.  Kept., 
Ill:  367,  1902.  —  Utah:  109.  Storrs,  U.  S.  Geol.  Surv.,  22d  Ann.  Kept., 
Ill:  415,  1902.  See  also  articles  in  U.  S.  G.  S.  Bulls.  285  (Sanpete 
County,  Weber  River,  Book  Cliffs),  316  (Pleasant  Valley  and  Iron 
County),  341  (n.  e.  Utah,  s.  w.  region),  371  (Book  Cliffs),  other  fields 
in  Bulls.  471  and  541.  —  Vermont:  110.  Hitchcock,  Amer.  Jour.  Sci., 
ii,  xv :  95,  1853.  (Lignite  at  Brandon.) — Virginia:  111.  Watson, 
Mineral  Resources  Virginia:  336,1907.  (General.)  112.  Shaler  and 
Woodworth,  U.  S.  Geol.  Surv.,  19th  Ann.  Rept.,  II:  393,  1898.  (Rich- 
mond basin.)  113.  Campbell,  U.  S.  Geol.  Surv.,  Bull.  Ill,  1893. 
(Big  Stone  Gap.) — Washington:  114.  Landes  and  Ruddy,  Wash. 
Geol.  Surv.,  II.  (General.)  114a.  Evans,  Wash.  Geol.  Surv.,  Bull. 
3,  1913.  (King  Co.)  See  also  U.  S.  'Geol.  Surv.,  Bulls.  474,  531,  and 
541.  —  West  Virginia:  115.  White,  W.  Va.  Geol.  Surv.,  II,  1903.  (Gen- 
eral.) 115a.  White,  W.  Va.  Geol.  Surv.,  Bull.  2:  209,  1911.  (Analyses.)  - 
Wyoming:  116.  Storrs,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  Ill:  415, 
1902.  (General.)  117.  U.  S.  Surv.,  Bulls.  225  (Bighorn  Basin),  260 
(Black  Hills),  285  (Uinta  County),  316  (Central  Uinta  County,  Lander 
field,  Carbon  County,  Laramie  Basin),  341  (Bighorn  Basin,  Sheridan 
district,  Little  Snake  River,  Great  Divide  Basin,  Rock  Springs,  Casper 
Douglas  district).  118.  Veatch,  U.  S.  Geol.  Surv.,  Prof.  Pap.  56,  1908. 
(s.  w.  Wyo.)  For  other  individual  fields,  see  Ibid.,  Bulls.  471,  499,  531, 
and  543. 

Canada:  118a.  Dowling,  Can.  Geol.  Surv.,  Mem.,  59,  1915.  (General.) 
1186.  Porter  and  Durley,  Mines  Branch,  Investigation  of  Canadian 
Coals,  1912.  118c.  Cairnes,  Can.  Min.  Inst.,  XV:  364,  1913.  (Yukon.) 
118d.  Clapp,  Can.  Geol.  Surv.,  Mem.  51,  1914.  (Nanaimo.)  118e. 
Dowling,  Ibid.,  Rep.  No.  1035,  1915.  (Man.,  Sask.,  Alta.,  and  e. 
Brit.  Col.)  118/.  Dowling,  Ibid.,  Mem.,  8,  1911.  (Edmonton  field.) 
1180.  Dowling,  Ibid.,  Mem.,  69,  1915.  (Brit.  Col.)  118ft.  Hudson, 
Mines  Branch,  Spec.  Eire.,  1913.  (Sydney  field.)  Il8i.  Mallock, 
Can.  Geol.  Surv.,  Mem.,  9-E.,  1911.  (Bighorn  Basin,  Alta.)  118/. 
Poole,  Ibid.,  XIV:  Pt.  M.  (Pictou  field.) 

REFERENCES    ON   PEAT 

119.  Ries,  N.  Y.  State  Museum,  54th  Ann.  Rept.,  1903.  (N.  Y.,  Origin 
and  uses  in  general,  Bibliography.)  120.  Carter,  Ont.  Bur.  Mines,  Rept. 
for  1903.  (General.)  121.  Shaler,  U.  S.  Geol.  Surv.,  12th  Ann.  Rept., 
p.  311.  (Peat  and  swamp  soils.)  122.  Roller,  Die  Torfindustrie,  Vienna, 
1889.  123.  Wilder  and  Savage,  la.  Geol.  Surv.,  Bull.  2,  1905.  (la.)  124. 
Taylor,  Ind.  Dept.  Geol.  Nat.  Res.,  31st  Ann.  Rept.,  1906.  125.  Par- 
melee  and  McCourt,  N.  J.  Geol.  Surv.,  Rept.,  1905:  223,  1906.  126. 
Nystrom,  Dept.  Mines  Can.,  Spec.  Bull.,  1908.  (Manufacture  and  uses.) 
127.  Davis,  Mich.  Geol.  Surv.,  Ann.  Rept.,  1906:  105,  1907.  (General 
and  Mich.)  128.  Bastin  and  Davis,  U.  S.  Geol.  Surv.,  Bull.  376,  1909. 
(Maine,  many  analyses.)  129.  Parsons,  N.  Y.  Geol.  Surv.,  23d  Ann. 
Rept.,  1904.  (N.  Y.)  130.  Taylor,  Ind.  Dept.  Geol.  Nat.  Res.,  31st  Ann. 


COAL  69 

Kept.,  73,  1906.  (Ind.)  131.  Davis,  Bur.  Mines,  Bull.  38:  165,  1913. 
(Origin.)  132.  Davis,  Econ.  Geol.  V:  623,  1910.  (Salt  marsh  formation.) 
133.  Dachnowski,  O.  Geol.  Surv.,  4th  ser.,  Bull.  16,  1912.  (Ohio.)  134. 
Harper,  Fla.  Geol.  Surv.,  3rd  Kept.:  197,  1910.  (Fla.) 

For  Canada  see  reports  issued  by  Mines  Branch,  dealing  especially  with 
technology  and  digging  of  peat.  Among  them:  135.  Haanel,  Kept.  299. 
Values  of  Peat  for  Gas  and  Power  in  Producers.  136.  Anrep.  Canad.  Rep. 
266,  Canadian  Peat  Bogs  and  Peat  Industry. 


CHAPTER  II 
PETROLEUM,  NATURAL  GAS,  AND  OTHER  HYDROCARBONS 

Introductory.  —  Under  this  head  are  included  four  well-known 
substances,  viz.  natural  gas,  petroleum,  mineral  tar  or  maltha,  and 
asphaltum,  all  essentially  compounds  of  carbon  and  hydrogen  - 
hydrocarbons  —  or  mixtures  of  such  compounds.  In  addition  they 
may  contain  many  impurities,  such  as  sulphur  compounds,  oxidized 
and  nitrogenous  substances,  etc.,  whose  exact  nature  may  be  doubtful. 

The  hydrocarbons  are  divisible  primarily  into  a  number  of  regular 
series,  each  of  which  has  a  generalized  formula  as  indicated  below. 

1.  CnHon+2  6.  CnH2n-8 

2.  CnHon  7.  CnH2n-30 

3.  CnHsu-2  8.  CuH2n_12 

4.  CnHto-4 

5.  CnHsn— 6  18.  CnH2n— 32 

Members  of  the  first  eight  series  have  been  discovered  in  petro- 
leum. Of  the  above  formulas,  the  first  represents  the  paraffin 
hydrocarbons,  beginning  with  marsh  gas  or  methane,  CH4,  and 
ranging  at  least  as  high  as  the  compound  C-xRw.  Methane  is 
gaseous,  the  middle  members  of  the  series  are  liquids,  while  the 
higher  members  are  solids,  like  ordinary  paraffin.  Members  of  the 
second  series  are  also  important  in  petroleums,  especially  the  olefine 
subseries.  The  third  or  acetylene  series  is  represented  in  some 
petroleums  by  its  higher  members.  The  fifth  or  benzine  series 
occurs  in  nearly  all  petroleums,  but  not  in  large  amounts. 

Properties   of  Petroleum   (4,  10,  12).  — Crude   petroleum  is  a 
liquid  of    complex  composition  and  variable  color  and  density. 
It  consists  of  a  mixture  of  hydrocarbons,  mainly  liquid,  with 
some  gase'ous  and  solid  ones,  the  last  being  in  solution.1 

Oils  which  contain  chiefly  paraffin  hydrocarbons,  and  which  usually 
yield  paraffin  scales  when  the  heavier  distillates  are  subjected  to  a  freezing 
temperature,  may  be  said  to  have  a  paraffin  base.  Those  containing  asphaltic 
bodies,  and  yielding  on  evaporation  a  residue  consisting  essentially  of  as- 

1  For  a  resume  of  the  different  hydrocarbons  discovered  in  American  and  Cana- 
dian oils,  see  F.  W.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  491.  Much  general  information 
also  in  Johnson  and  Huntley,  Principles  of  Oil  and  Gas  Production,  New  York,  1916 

70 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    71 

phalt,  are  said  to  have  an  asphaltic  base.  These  two  terms,  though  much 
used  formerly,  are  rapidly  falling  into  disuse;  because  some  asphaltic  oils 
may  also  yield  paraffin  wax. 

Sulphur  may  be  present  as  a  constituent  of  hydrogen  sul- 
phide, as  free  sulphur,  or  as  organic  sulphur  compounds.  The 
first  two,  which  occur  for  example  in  the  Mexican,  and  in  the 
Gulf  Coast  oils  of  Texas  and  Louisiana,  are  not  difficult  to  re- 
move. Organic  sulphur,  such  as  occurs  in  the  Lima,  Ohio,  and 
the  Ontario  limestone  oils,  is  more  difficult  to  eliminate,  even 
though  in  small  amounts. 

Most  petroleum  contains  some  nitrogen,  but  it  rarely  exceeds 
2  per  cent,  except  in  some  California  oils,  where  it  may  reach 
10  or  20  per  cent.1 

The  following  are  analyses  of  several  petroleums  from  American 
and  foreign  localities :  — 

ELEMENTARY  ANALYSES  OF  PETROLEUM 


PER  CENT 

SPECIFIC 

C 

H 

o 

H20=T1 

Heavy  oil,  W.  Va.      .     . 

83.5 

13.3 

3.2 

.873 

Light  oil,  W.  Va.       .     . 

84.3 

14.1 

1.6 

.8412 

Heavy  oil,  Pa.       .     .     . 

84.9 

13.7 

1.04 

.886 

Light  oil   Pa 

82.0 

14.8 

3.2 

.816 

Parma,  Italy     .... 

84.0 

13.4 

1.8 

.786 

Hanover,  Germany   .     . 

80.4 

12.7 

6.9 

.892 

Galicia,  Austria     .     .     . 

82.2 

12.1 

5.7 

.870 

Light  oil,  Baku,  Rus.     . 

86.3 

13.6 

0.1 

.884 

Heavy  oil,  Baku,  Rus.    . 

86.6 

12.3 

1.1 

.938 

Java    

87.1 

12.0 

0.9 

.923 

Beaumont,  Texas       .     . 

86.8 

13.2 

— 

.920 

Most  crude  oils  are  opaque  by  transmitted  light,  except  in 
thin  layers.  Some  of  the  thinner  grades  of  Pennsylvania  oils, 
and  some  Alberta  ones  may  show  pale  straw,  yellow,  red,  and 
brown  colors. 

Crude  oils  usually  have  a  green  cast  by  reflected  light,  but 
otherwise  vary  in  color  from  yellow  to  black. 

Oils  from  different  fields  vary  in  their  refractive  indices  (26), 
and  this  property  may  be  of  use  for  purposes  of  identification. 

They  also  show  double  refraction.     As  a  rule  crude  oil  rotates 


Jour.  Soc.  Chem.  Ind-,  XIX:   505,  1900. 


72 


ECONOMIC  GEOLOGY 


the  plane  of  polarization  to  the  right,  but  some  rotate  it  to  the 
left,  while  others  may  be  optically  inert. 

Petroleums  commonly  vary  in  specific  gravity  between  about 
.8  and  .98,  the  following  being  some  of  the  limits  shown  by 
American  oils: — 

SPECIFIC  GRAVITY  OF  SOME  AMERICAN  PETROLEUMS 


STATE 

SPECIFIC  GRAVITY 

GRAVITY  BEAUME* 

California  (Placerita  Canon) 
Pennsylvania                      ... 

.777  + 
.801-.817 

50  + 
46.2-42.6 

Ohio 

816-  860 

42  8-32.5 

Kansas  

.835-1.000 

38.8-10.0 

\Vest  Virginia 

.841-.873 

37.6-30.0 

BeaumoD  t   T6xas 

904-925 

24  8-31  1 

"Wyoming    

.912-.945 

23.3-11.9 

California   

.920-  983 

21.9-12.3 

The  viscosity  of  the  oil  increases  with  the  specific  gravity. 

The  temperature  at  which  crude  petroleum  solidifies  ranges  from  82° 
F.  in  some  Burma  oils  to  several  degrees  below  zero  in  certain  Italian  oils. 
The  flashing  point,  or  the  lowest  temperature  at  which  inflammable  vapors 
are  given  off,  may  be  as  low  as  zero  degrees  in  the  Italian  oils  to  as  high  as 
370°  F.  in  an  oil  found  on  the  Gold  Coast  of  Africa,  but  these  are  extreme 
limits.  There  is  also  a  great  range  in  the  boiling  point,  which  is  180°  F. 
in  some  Pennsylvania  oils  and  338°  F.  in  oils  found  at  Hanover,  Germany. 

The  various  liquid  hydrocarbons  making  up  crude  petroleum  vary  in 
their  specific  gravity  and  boiling  point.  The  more  important  oils  which  can 
be  separated  from  crude  petroleum  by  distillation  are  gasoline,  benzine, 
heavy  naphthas,  and  residuum.  Those  with  a  paraffin  base  are  generally 
lighter  and  more  valuable  on  account  of  the  higher  quantity  and  quality 
of  the  naphthas,  illuminating  oils,  and  lubricating  oils  which  they  produce. 
Those  with  an  asphalt  base  are  of  inferior  quality  and  .chiefly  valuable  for 
fuel.  Their  transportation  by  pipe  lines  is  also  more  difficult. 

The  percentage  of  the  different  distillates  varies. 
The  following  average  percentages  of  distillates  were  yielded  by 
the  oils  of  several  fields  in  1902  (Oliphant) :  — 

1  A  specific  gravity  of  1,  compared  with  water,  is  10°  on  the  Beaume  scale. 
Conversion  from  one  scale  to  the  other  may  be  made  by  the  following  formula: — 


Beaume  = 


140 


Sp.  Gr. 


-  130;  or  Sp.  gr. 


140 


130  +  Beaume 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    73 


APPALACHIAN 
FIELD 

LIMA,  IND., 
FIELD 

KANSAS 
FIELD 

Naphthas     

20.1 

10.9 

18 

Illuminating  oils  

61.4 

488 

30 

Lubricating  and  heavy  oils     . 
Residuum 

7.1 
63 

17.2 

25 

Loss  from  uncondensed  prod- 
ucts and  water       .... 

5.1 

23.0 

27 

In  the  following  table  (p.  74)  there  are  given  a  number  of  de- 
terminations of  distillates,  etc.,  published  by  Dr.  David  T.  Day, 
of  the  United  States  Geological  Survey,  and  in  part  made  by 
him. 

Properties  of  Natural  Gas.  —  This  consists  chiefly  of  marsh 
gas  —  fire  damp  —  CH4.  It  is  colorless,  odorless,  burns  often 
with  a  luminous  flame,  and  when  mixed  with  air  it  is  highly  ex- 
plosive. 

Ethane  (XZ^He),  the  next  member  of  the  marsh-gas  series,  may 
exist  in  considerable  quantities  in  natural  gas.  Ethylene,  or  ole- 
fiant  gas  (€2114) ,  burns  with  a  much  more  luminous  flame  than  the 
two  preceding,  but  it  rarely  exists  in  American  gas  in  amounts 
greater  than  a  small  fraction  of  1  per  cent.  Carbon  monoxide 
occurs  only  in  very  small  quantities,  and  the  same  is  true  of 
carbon  dioxide-  Nitrogen  is  found  in  variable  amounts,  and 
oxygen  is  not  uncommon,  but  when  present  in  large  quantity  in 
an  analysis,  it  may  be  due  to  contamination  of  the  sample 
analyzed  with  air. 

The  analyses  given  on  p.  78  represent  a  number  of  American 
occurrences.  It  will  be  seen  that  marsh  gas  is  the  predominating 
constituent  in  nearly  all  of  them. 

The  gas  from  Dexter,  Kansas  (No.  4  of  the  table  on  page  78), 
is  interesting  because  of  its  high  content  of  nitrogen.  Of  47 
samples  of  gas  examined  l  by  Cady  and  McFarland,  all  except  one 
showed  helium,  in  amounts  averaging  .10  per  cent.  One  Kansas 
sample  contained  1.84  per  cent  more  than  the  others,  and  this 
same  one  carried  the  high  nitrogen  contents  referred  to  above. 
The  rare  element  neon  was  also  discovered. 


1  Jour.  Amer.  Chem.  Soc.,  XXIX:  1524. 


74 


ECONOMIC   GEOLOGY 


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78 


ECONOMIC   GEOLOGY 


ANALYSES  OF  NATURAL  GAS 


No. 

METHANE, 
(CH4) 

ETHANE 
(C2H6) 

OLEFINE 
(C2H4) 

CARBON 
DIOXIDE 
fCOj) 

CARBON 
MONOXIDE 

(CO) 

OXYGEN 

NITROGEN 

HYDROGEN 

HELIUM 

HYDROGEN 
SULPHIDE 

1  .... 

94.40 









.23 

5.08 

.183 



2  .... 

96.20 

.78 





.11 

tr. 

2.46 

.18 

.27 



3  .... 

82.25 



.12 

.61 



tr. 

16.40 

.616 

— 

4  .... 

14.85 

.41 







.20 

82.70 

tr. 

1.84 



5  .     .     .-  . 

62.93 





.50 

tr. 

.70 

24.36 

11.51 

undet. 



6  .... 

95.35 

1.60 

2.50 

.55 





undet. 



7  .... 

13.97 





.10 

.05 

.05 

85.83 

undet. 



8  .     .    ;.     / 

73.81 





.81 



3.46 

21  .92 

undet. 



9  .     . 

92.67 



.25 

.25 

.45 

.35 

3.53 

2.35 

undet. 

.15 

10  .     .     .     . 

92.61 



.30 

.26 

.50 

.34 

3.61 

2.18 

undet. 

.20 

11  .... 

90.01 

.20 



tr. 

9.79 



undet. 



12  .... 

98.90 

.40 





.70 

undet. 



13  ...     . 

80.94 

14.60 





.40 

.20 

3.46 

tr. 

undet. 



14  .     . 

86.48 

7.65 





.50 

.30 

4.87 



undet. 



15  

98.40 







.95 

tr. 

.40 

tr. 

undet. 

tr. 

16.     . 

94.20 



.39 

1.06 

1.13 

.92 

3.31 



tr. 



17.    .......    . 

92.20 

—  - 



1.40 

.21 

tr. 

5.59 

.40 



.20 

is  .  .  ;  . 

96.57 











2.69 





.74 

Minima  .     . 

14.33 





.05 



.10 

.60 





Maxima  .     . 

98.30 

30.40 

9.00 

85.83 





1.  lola,  Kas.,  p.  270;  2.  Buffalo,  Kas.,  p.  270;  3.  Fredonia,  Kas.,  p.  270; 
4.  Dexter,  Kas.,  p.  270;  5.  Stockton,  Cal.,  p.  252;  6.  From  glacial  drift,  Dawson, 
la.,  p.  252;  .7.  Princeton,  111.,  p.  251;  8.  Pittsfield,  111.,  p.  251;  9.  Muncie,  Ind., 
p.  249;  10.  Trenton  limestone,  Findlay,  O.,  p.  248;  11.  Kane,  McKean  Co.,  Pa., 
p.  247;  12.  Pittsburg,  Pa.,  p.  247;  13.  Big  Injun  sand,  Shinnston,  W.  Va.,  p.  242. 
14.  Fifty-foot  sand,  same  locality,  p.  242;  15.  Trenton  limestone,  Baldwinsville; 
N.  Y.,  p.  241;  16.  Gas  from  coal  mine,  Scranton,  Pa.,  1-16,  quoted  by  Kas.  Geol. 
Surv.,  IX  on  page  given  after  each;  17.  Kent  County,  Ont.;  18.  Welland,  Ont. 


For  additional  analyses  of  gas  used  in  different  cities,  see  Bur- 
rell,  G.  A.,  and  Oberfell,  G.  G.,  Bur.  Mines,  Tech.  Pap.  109, 
1915. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    79 


The  following  table  brings  out  the  essential  differences  between  natural 
gas  and  other  fuel  or  illuminating  gases. 

Analyses  of  natural  and  manufactured  gases. 


AVER. 

AVER.  PA. 
&  W.  VA. 

AVER.  O. 
&  IND. 

AVER. 
KAS. 

AVER. 
COAL 
GAS 

AVER. 
WATER 
GAS 

PRO- 
DUCER 
GAS  BIT. 

COAL 

Marsh  gas,  CH4    . 

80.85 

93.60 

93.65 

40.00 

2.00 

2.05 

Other  hydrocarbons 

14.00 

.30 

.25 

4.00 

.00 

.04 

N   

4.60 

3.60 

4.80 

2.05 

2.00 

56.26 

C02     

.05 

.20 

.30 

.45 

4.00 

2.60 

CO 

.40 

.50 

1.00 

6.00 

45.00 

27.00 

H   

.10 

1.50 

.00 

46.00 

45.00 

12.00 

H2S     . 

.00 

.15 

.00 

.00 

.00 

.00 

0    

tr. 

.15 

.00 

1.50 

1.50 

.05 

Lbs.  in  1000  cu.  ft.   . 

47.50 

48.50 

49.00 

33.00 

45.60 

75.00 

Sp   gr  

.624 

.637 

.645 

.453 

.600 

985 

B.T.U.  per  1000  cu.  ft. 

1,145,000 

1,095,000 

1,100,000 

755,000 

350,000 

155,000 

Origin  of  Oil  and  Gas.  —  That  the  solid,  liquid,  and  gaseous  hydro- 
carbons are  more  or  less  closely  related  is  evident  from  the  fact  that 
the  gases  given  off  by  petroleum  are  similar  to  those  predominating 
in  natural  gas,  while  the  exposure  of  many  petroleums  to  the  air 
results  in  a  change  to  a  viscous  mass  and  finally  to  a  solid  asphalt 
or  paraffin-like  substance.  It  is  a  well-known  fact  that  petroleum 
is  rarely  free  from  natural  gas,  although  this  gas  may  sometimes 
form  alone,  as  in  coal  mines,  or  from  decaying  vegetation  in  stag- 
nant pools.  The  origin  of  the  hydrocarbon  compounds  has  been 
the  subject  of  much  speculation  among  both  chemists  and  geolo- 
gists, the  former  for  a  time  arguing  for  an  inorganic  or  mineral  origin, 
the  latter  for  an  organic  derivation,  the  same  evidence  curiously 
enough  being  sometimes  used  by  persons  holding  opposite  views. 

It  cannot  be  said  that  the  matter  has  yet  been  settled  to  the  satis- 
faction of  all,  although  it  is  probable  that  the  majority  of  observers 
admit  the  organic  origin  of  petroleum.  One  cause  of  uncertainty  is 
that  oils,  unlike  coals,  do  not  usually  contain  visible  traces  of  their 
original  constituents.  Moreover,  we  had  until  recently  few  un* 
doubted  known  instances  of  the  recent  formation  of  petroleum 
under  conditions  similar  to  those  found  in  the  older  rocks. 

Inorganic  Theories  (1,  2a,  2d,  3a,  10).  —  Several  theories  have 
been  advanced  to  account  for  an  inorganic  origin  of  oil.  Hum- 
boldt  was  the  first  to  propose  it,  in  1804,  although  it  was  later 
more  definitely  stated  by  Berthelot,1  and  still  later  elaborated 
by  Men  del  jeff,2  under  whose  name  it  is  frequently  referred 

1  Comptes  Rendus,  LXII:   949,  1866. 

2  Ber.  Deutsch.  Chem.  Gesell.,  X:  229,  1877,  and  Jour.  Chem.  Soc.,  XXXII:  283. 


80  ECONOMIC  GEOLOGY 

to.  The  general  substance  of  these,  and  several  others'  hypoth- 
eses is  that  surface  water  has  percolated  downward  through  the 
earth's  crust,  where  on  reaching  the  heated  interior  it  becomes 
converted  into  steam,  which,  attacking  the  carbide  of  iron, 
forms  hydrocarbons,  which  make  up  the  oil  and  gas. 

From  a  purely  chemical  standpoint,  this  theory  is  reasonable, 
and  the  production  of  hydrocarbons  by  this  method  has  been  done 
experimentally,  but  it  does  not  accord  with  geologic  facts.  If 
petroleum  were  formed  in  this  manner,  we  should  expect  to  find  it 
widely  distributed  through  the  oldest  rocks  of  the  earth's  crust. 

On  the  contrary,  hydrocarbon  compounds  like  oil,  gas,  and  as- 
phalt are  practically  unknown  in  crystalline  rocks.  In  Ontario,  a 
hard  compressed  asphalt  is  found  in  them,  but  it  is  sign'""ant  that 
this  material  (Anthraxolite)  which  was  probably  origin,* •  petro- 
leum, occurs  in  rocks  which  may  be  metamorphosed  sediments.  A 
second  case  is  found  in  California  (17),  where  oil  occurs  in  a 
much-folded  crystalline  schist,  but  its  associations  are  such  that  it 
may  have  been  derived  from  neighboring  sediments. 

A  possible  point  in  favor  of  the  derivation  of  oil  and  gas  from  carbides 
has  been  noted  by  Becker  (l),  who  has  called  attention  to  the  fact  that 
the  irregularities  of  the  curves  of  equal  magnetic  declination  are  strongly 
marked  in  the  principal  oil  regions.  While  the  agreement  is  not  a  very 
close  one,  it  is  most  marked  in  the  Appalachian  field.  There  are,  however, 
some  systematic  irregularities,  as  in  the  New  Jersey  magnetite  regions, 
which  are  not  known  to  contain  any  oil.  Becker  believes  that  the  coin- 
cidence between  the  petroleum  occurrences  and  local  disturbances  of  the 
compass  are  too  numerous  to  be  attributable  to  mere  accident,  and  that 
there  must  be  a  direct  or  indirect  historical  connection  between  the  two 
phenomena  in  the  regions  of  coincidence,  thus  suggesting  the  possibility  of 
the  oil  being  derived  from  iron  carbides. 

Tarr  (12a),  however,  disputes  Becker's  conclusions,  pointing  out:  (1) 
That  the  isoclinals  or  lines  of  magnetic  dip  do  not  show  any  evidence 
of  disturbances  due  to  magnetic  masses  in  the  oil  regions;  (2)  that  the 
secular  variation  is  a  shifting  of  the  isogonics  or  lines  of  magnetic  declination, 
indicating  that  the  origin  of  this  variation  is  not  due  to  a  stationary  mass; 
and  (3)  the  magnetism  of  iron  is  lost  at  high  temperatures,  hence  it  must 
exist  at  comparatively  shallow  depths  to  be  magnetically  effective. 

Volcanic  Theory.  —  A  second  inorganic  theory  advocated  by  several, 
and  in  recent  years  expounded  with  great  vigor  and  detail  by  E.  Coste 
(2d,  3a),  is  the  theory  of  volcanic  origin  of  the  hydrocarbons. 

Mr.  Coste  believes  that  all  hydrocarbons  cannot  be  of  animal  or  vege- 
table origin,  but  must  be  of  volcanic  derivation  for  the  following  reasons: 
1.  Animal  remains  are  never  entombed  in  rock  formations.  2.  Vegetable 
remains  in  rocks  decompose  into  carbonaceous '  matter.  3.  Further  distilla- 
tion of  carbonaceous  matter  has  not  taken  place  in  nature.  4.  Gaseous 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    81 

liquid,  and  solid  hydrocarbons  are  products  of  volcanic  emanations.  5.  Oil 
and  gas  are  under  strong  pressure,  and  hence  must  be  of  volcanic  origin, 
for  nothing  else  could  produce  this  pressure.  6.  In  some  oil  fields  heated 
gas  and  water  are  met  with.  7.  Oil  and  gas  fields  are  located  along  faulted 
and  fissured  zones  of  the  earth's  crust,  parallel  to  great  orogenic  (mountain- 
making)  and  volcanic  dislocations.  8.  Oil,  gas,  and  bituminous  matter 
are  never  indigenous  to  the  strata  in  which  they  are  found.  9.  The  density 
of  the  rocks  precludes  possibility  of  anything  but  volcanic  pressure  having 
forced  them  upward. 

The  arguments  against  some  of  these  points  may  be  mentioned  under 
the  same  numbers :  1.  Animal  remains  are  entombed  in.  rocks,  otherwise  we 
could  not  have  fossils  of  those  lacking  hard  parts.  2.  Vegetable  remains  in 
rock  have  been  proven  to  decompose  into  hydrocarbons,  as  evidenced  by. 
natural  gas  supplies  found  in  glacial  drift ;  moreover,  some  coal  seams  have 
oil  seepages.  3.  While  hydrocarbons  are  known  to  occur  in  some  volcanic 
emanations,  they  might  be  formed  by  the  direct  union  of  carbon  and  hydro- 
gen of  tV1  gases,  or  have  been  distilled  out  of  sedimentary  rocks  through 
which  t  u*ya  passed.  Moreover,  they  are  frequently  formed  from  decay- 
ing vegetable  matter.  5.  The  pressure  may  be  due  to  the  natural  expansive 
force  of  the  gas.  7.  Oil  and  gas  fields  are  sometimes  found  in  regions  of 
but  little  disturbance,  as  Illinois,  Medicine  Hat,  Alberta,  etc.  8.  This  may 
be  true,  but  they  are  often  clearly  shown  to  have  come  from  adjoining  beds. 
9.  If  volcanic  pressure  forced  this  oil  and  gas  up  through  many  feet  of 
dense  rock,  why  were  they  not  forced  all  the  way  to  the  surface  ? 

One  may  also  add  that  the  restriction  of  oil  and  gas  to  sedimentary 
rocks  is  not  in  accordance  with  a  volcanic  origin,  neither  is  the  decrease  in 
pressure  which  most  wells  show  with  time. 

Organic  Theory.  —  This  considers  that  petroleum  has  been 
formed  by  the  decomposition  of  organic  matter  buried  in  the 
rocks,  although  the  exact  changes  involved  are  somewhat  un- 
certain. 

But  even  though  many  are  in  agreement  on  the  theory  of  organic 
origin,  they  differ  as  to  whether  the  oil  came  from  animal  or 
vegetable  matter. 

Adherents  of  the  former  view  include  Hofer,*1  Newberry,2  Hunt,  Zalo- 
ziecki,3  Engler,4  and  others,  while  among  those  of  the  latter  are  numbered 
Lesquereux,  Phillips,  Kramer,  Spilker,  and  others. 

Perhaps  the  majority  of  geologists  and  even  others  have 
unconsciously  assumed  that  petroleum  has  been  derived  from 
land  plants,  and  while  in  some  cases  this  may  be  so,  some  rather 

1  Proc.  Manchester  Lit.  Phil.  Soc.,  Ill:    136,  and  Das  Erdol,  p.  118. 
2Geol.  Surv.  Ohio,  1878,  Pt.  I:    125  and  174. 

3  Dingler's  Polytech.  Jour.,  CCLXXX:    69,  85  and  133;    Chem.  Zeit.,  XV: 
1203. 

4  Redwood,  Petroleum  and  its  Products,  1906,  p.  259, 


82  ECONOMIC   GEOLOGY 

weighty   objections   can   be   urged   against   it.     These   are   the 
following : — 

1.  There  is  a  general  lack  of  association  of  coal  or  lignite  and 
oil.  2.  Where  lignite  or  carbonized  wood  is  found  with  oil  it 
has  lost  none  of  its  essential  constituents.  3.  There  is  a  great 
chemical  difference  between  lignite  tar  oils  and  natural  petro- 
leums. 4.  It  requires  a  high  temperature  (geologically  speaking) 
to  convert  wood  into  liquid  bitumen,  and  leave  no  trace  of  its 
original  structure.1  5.  An  argument  of  doubtful  weight  is  that 
limestones,  being  of  marine  origin,  the  oil  in  them  could  not  be 
derived  from  land  plants. 

The  following  arguments  may  be  mentioned  in  favor  of  the 
derivation  of  petroleum  from  marine  plants  such  as  seaweeds: 
1.  Saline  water  associated  with  some  oils  carries  iodine >  2. 
Certain  seaweeds  found  on  the  coast  of  Sardinia  become  covered 
with  an  oily  coating  while  decomposing.3  3.  In  some  localities 
the  diatom  cases  found  in  rocks  are  known  to  contain  small 
globules  of  oil,  which  have  in  some  regions  been  regarded  as 
a  source  of  petroleum  (19).  4.  The  so-called  algal  remains  of 
bog-head  coals  were  formerly  regarded  as  evidence  of  marine 
origin,  but  these  minute  bodies  are  now  recognized  as  spores r 
the  coals  rich  in  them  being  petroliferous  or  highly  bituminous, 
and  according  to  Jeffrey  *  in  some  form  or  other  are  the  mother 
substance  of  oil  or  gas.5 

Some  have  also  considered  that  the  oil  may  have  been  de- 
rived, in  part  at  least,  from  animal  remains,  the  oil  thus  having 
a  dual  origin. 

Some  have  claimed  that  the  optical  activity  of  oil  shows  it 
to  be  of  undoubted  organic  origin  (l),  for  the  reason  that  mai  y 
petroleum  products  have  the  power  of  rotating  the  plane  of 
polarization  of  light,  as  is  done  by  sugar,  lactic  acid,  and  other 
organic  compounds.  These  optical  phenomena  are  not  shown 
by  inorganically  synthesized  petroleum,6  and  hence  it  is  argued 
that  the  substances  to  which  it  is  believed  to  be  due  are  only  of 
organic  derivation.  These  substances  are  cholesterol,  found  in 
the  fatty  parts  of  animals,  and  phytosterol,  found  in  plants. 

1  Such  a  process  would  be  likely  to  occur  only  where  a  bed  of  land  plants  was 
approached  by  an  intrusive. 

2  Watts,  Calif.  State  Min.  Bur.,  Bull.  19:  202. 

3  Redwood,  Petroleum  and  its  Products,  2d  edition,  I:  126,  142. 
4Econ.  Geol.,  IX:   741,  1914. 

5  C.  A.  Davis  has  recently  identified  alga3  in  Utah  oil  shales. 
8  Some  natural  petroleums  are  now  found  to  be  inert  optically. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    83 

If  the  oils  are  derived  from  animal  and  plant  remains  of 
marine  character,  it  is  possible  that  the  nitrogenous  portions  were 
eliminated  by  bacterial  action  soon  after  the  death  of  the  organ- 
ism, and  before  it  became  buried  under  sediments.  Subsequently 
the  oil  was  produced  by  decomposition  of  the  fatty  matter  of 
the  plants  and  animals.  Some  geologists,  including  Orton  (4) 
and  Newberry  (Ohio  State  Agric.  Kept.  1859)  believed  that  the 
formation  of  petroleum  has  taken  place  at  lower  temperatures; 
but  others,  including  Peckham  (6),  have  considered  heat  nec- 
essary. In  the  case  of  Appalachian  oils  the  folding  of  the  strata 
is  supposed  to  have  supplied  this  heat. 

Mode  of  Occurrence.  (6,  8,  9,  13).  —  Oil  is  rarely  found  without 
some  gas,  but  gas  may  occur  without  oil,  and  in  either  case 
saline  water  may  be  present. 


Kansas  Crude  1      Oread  1      Oread  3      Kansas  Crude  No.l        Oread  No.l 


Oread  No.2 


Oread  No.5 


SECTION  27 


Oread  2 


Oread  I 


.764 

'--Oil 

834 

Oil 


798 
/Gas 


13 


SECTION  26 


O  Oread  5 


FIG.  26.  —  Showing  positions  and  vertical  sections  of  wells  southeast  of  Hum- 
boldt,  Kas.,  and  differing  thickness  and  number  of  sands  in  neighboring  wells. 
(Kas.  Geol.  Sure.,  IX.)  ^ 


In  the  first  discovered  fields,  the  oil  and  gas  were  found  in 
porous  sandy  strata,  varying  from  fine-grained  sandstones  to 
conglomerates.  These  rocks  were  termed  sands,  and  the  area 
of  porous  oil  sand  was  called  the  pool.  Later  discoveries  in 
Ohio  and  Indiana  showed  that  the  gas  and  oil  might  occur  in 
limestone  also,  while  in  a  few  fields  (Florence,  Colorado,  and 
parts  of  California)  the  oil  has  accumulated  in  fissures  in  shale, 
produced  by  earth  movement. 

The  number  and  thickness  of  the  oil  and  gas  sands  may  some- 


84 


ECONOMIC  GEOLOGY 


times  vary  in  different  parts  of  the  same  field  (Figs.  26  and  27), 
thereby  making  correlation  difficult. 


fi 


HSDVW3NOO      AN3H93T1V 


NV:NVAlASNN3d 


NVIddlSSISSIW 


The  thickness  of  the  producing  rock  ("  pay  sand  ")  varies 
in  the  different  fields.  White,  referring  to  West  Virginia,  re- 
gards 5  feet  of  sand  as  sufficient  for  good  productive  territory, 
but  thicker  ones  are  found  in  the  Appalachian  field.  The 
Illinois  sands  range  from  2  to  over  30  feet  in  thickness,  while 
that  estimated  for  Spindle  Top  in  Texas  averages  75  feet.  The 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    85 

Kern  River  field  of  California  is  said  to  have  pay  sands  as  much 
as  100  feet  thick.1 

The  quantity  of  oil  which  a  cubic  foot  of  apparently  dense  rock 
can  hold  is  often  surprising.  White  estimated  that  fairly  produc- 
tive sands  may  hold  from  six  to  twelve  pints  of  oil  per  cubic  foot, 
but  that  probably  not  more  than  three-fourths  of  the  quantity 
stored  in  the  rock  is  obtainable.  According  to  Day  (53)  it  has  been 
customary  to  consider  10  per  cent  as  near  the  average  porosity  of 
the  pay  sand,  with  a  latitude  of  variation  from  practically  nothing  in 
damp  shales  to  over  30  per  cent  in  the  most  porous  strata.  The 
degree  of  openness  of  the  pores  will,  however,  govern  the  rate  of  flow 
of  oil  from  the  rock.2 

Pressure  of  Oil  and  Gas  Wells.  —  Since  both  oil  and  gas  usually 
occur  in  the  earth  under  pressure,  any  break  in  the  porous  rock  or 
reservoir  which  contains  them  allows  them  to  escape,  frequently 
giving  rise  to  surface  indications,  and  the  force  with  which  oil  and 
gas  oftentimes  issue  from  a  well  indicates  the  pressure  under  which 
they  are  confined.  It  is  sometimes  sufficient  to  blow  out  the  drill- 
ing tools  and  casing,  as  well  as  to  cause  the  oil  to  spout  many  feet 
into  the  air. 

There  are  several  remarkable  cases  of  the  amount  spouted  by  these 
gushing  wells.  One  of  these  is  the  famous  Lucas  well  at  Beaumont,  Texas, 
which  in  1901  for  nine  days  gushed  a  6-inch  stream  to  a  height  of  160 
feet,  at  the  rate  of  75,000  barrels  per  day.  This,  however,  is  small  com- 
pared with  the  records  of  some  Mexican  oil  wells.  Although  many  wells 
flow  when  first  drilled,  this  does  not  usually  continue  long,  and  the  oil  then 
has  to  be  brought  to  the  surface  by  pumping.  The  depth  of  the  wells  drilled 
in  the  United  States  ranges  from  250  to  4000  feet. 

The  maximum  pressure  which  a  well  develops  when  closed  has 
been  called  rock  pressure.  As  a  result  of  his  studies  in  the  Ohio- 
Indiana  field,  Orton  (42)  found  that  the  rock  pressure  was  the  same 
as  that  of  a  column  of  water  whose  height  was  equal  to  the  differ- 
ence in  elevation  between  the  level  of  Lake  Erie  and  that  of  the  oil 
or  gas-bearing  stratum.  He  therefore  considered  it  to  be  hydro- 
static pressure.  This  theory,  while  apparently  applicable  in  many 
localities,  was  found  to  be  inadequate  to  explain  the  great  pressure 
shown  in  many  shallow  wells.  In  these,  as  also  in  deep  ones,  the 
pressure  is  thought  by  many  to  be  due  to  the  expansive  force  of  the 
imprisoned  gas. 

Either  the  drilling  of  additional  wells  or  a  drain  by  excessive  use 

1  U.  S.  G.  S.,  Bull.  394:  34,  1909. 

2  Washburne,  Amer.  Inst.  Min.  Engrs.,  Bull.,  Feb.  1915. 


86 


ECONOMIC  GEOLOGY 


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PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    87 

from  wells  already  bored  commonly  causes  a  slow  decrease  in  pres- 
sure in  an  oil  or  gas  field.  Thus  in  the  natural  gas  region  of  Findlay, 
Ohio,  the  rock  pressure  in  1885  was  450  pounds  per  square  inch;  400 
in  1886;  360-380  in  1887;  250  in  1889;  170-200  in  1890.  Some 
West  Virginia  wells  have  shown  a  measured  rock  pressure  of  1110 
pounds  per  square  inch  and  an  estimated  pressure  of  2000  pounds. 

It  has  been  not  infrequently  noticed,  however,  that  the  opening 
up  of  one  or  more  wells  close  to  a  good  producer  may  have  little  or 
no  effect  on  it. 

The  table  on  page  86  (53)  gives  the  closed  or  rock  pressure  in 
various  fields,  in  different  years.  They  are  interesting,  but  lose 
their  comparative  value  as  they  do  not  probably  in  all  cases 
represent  the  same  well. 

Classification  of  Oil  and  Gas  Sands. —  As  early  as  1861  T. 
Sterry  Hunt,  the  Canadian  geologist,  and  A.  Hofer,  the  Austrian 


a  GAS 


OIL 


C    WATER 


d    CAPROCK 


FIG.  28.  —  Section  of  anticlinal  fold  showing  accumulation  of  gas,  oil,  and  water. 
(After  Hayes.  U.  S.  Geol.  Surv.,  Bull.  212.) 


geologist,  called  attention  to  the  fact  that  oil  and  gas  occurrences 
appeared  to  be  associated  with  anticlinal  folds,  but  the  anti- 
clinal theory,  as  it  came  to  be  called,  was  most  fully  developed 
by  I.  C.  White  (13).  According  to  this  theory,  iri  folded  areas 
the  gas  collects  at  the  summit  of  the  fold,  with  the  oil  imme- 
diately below,  on  either  side,  followed  by  the  water  (Fig.  28). 
It  is,  of  course,  necessary  that  the  oil-bearing  stratum  shall  be 
capped  by  a  practically  impervious  one. 

If  the  rocks  are  dry,  then  the  chief  points  of  accumulation 
of  the  oil  will  be  at  or  near  the  bottom  of  the  syncline,  or  lowest 
portion  of  the  porous  bed.  If  the  rocks  are  partially  saturated 
with  water,  then  the  oil  accumulates  at  the  upper  level  of  sat- 
uration. 


88  ECONOMIC  GEOLOGY 

In  a  tilted  bed  which  is  locally  porous  and  not  so  throughout, 
the  oil,  gas,  and  water  may  arrange  themselves  according  to 
their  gravity  in  this  porous  part. 

While  the  anticlinal  theory  has  been  found  to  apply  in  many 
oil  regions,  some  doubt  has  been  raised  regarding  its  possible 
application  in  parts  of  southwestern  Pennsylvania  (6),  and 
even  other  localities. 

Many  occurrences  of  oil  and  gas  appear  to  be  associated 
with  anticlines,  but  there  are  others  which  are  either  related  to 
modifications  of  this  structure,  or  to  totally  unrelated  structures. 


Scale  of  Miles 


Dome 


EXPLANATIONS: 

.gg_ Structure-Contour  Lines, Showing 

"Lay"  of  Gas  Sands 

OOil  Well;  -$•  Gas  Well;-f  Dry  Hole;     «t>Shovv  of  Gas 


FIG.  29. —  Contour  map  of  "  sand," 
showing  occurrence  of  gas  on  a 
structural  dome  in  Oklahoma. 
(Clapp,  Econ.  Geol.  VIII.) 


EXPLANATIONS:  SCALE  OF  MILES 

^-~-110- .Structure  Contour  Lines  Showing 

Elevations  of  top  of  Berea  Sand  above,  tide 
&  Gas  Well  withjarge  production     . 
'•&  Gas  Well;with  small  production 
-$-DrjUole(,Xooll.orGaB) 


FIG.  30.  —  Gas  pool  coincident  with 
a  structural  terrace.  Class  Id. 
(Clapp,  Econ.  Geol.  V.) 


The  following  classification  has  been  suggested  by  Clapp  (2c). 

I.  Where  anticlinal  and  synclinal  structure  exists. 
a.  Strong  anticlines  standing  alone. 

(Eureka- Volcano    Burning    Springs    anticline    in 

West  Virginia.) 
6.  Alternating,  well-defined  anticlines  and  synclines. 

(Appalachians,  southern  Indiana,  and  Illinois,  etc.) 
c.  Monoclinal  slopes  with  change  in  dip. 
(Southeast  Ohio  pools.) 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    89 

d.  Terrace  structures. 

(Southwest  Ohio.) 

e.  Broad  geanticlinal  folds. 

(Trenton  limestone,  Ohio.) 
II.  Domes  or  quaquaversal  structures, 
a.  Anticlinal  bulge  type. 

A  variation  of  I  and  merges  into  it. 

(Rogersville,  Pa.,  Geol.  Atl.  Fol.  146,  a  type  case.) 
6.  Saline  dome  type. 

(Southern  Louisiana  and  Texas.) 
c.   Volcanic  neck  type. 

(Northeast  Mexico.) 

III.  Along  sealed  faults. 

(Lompoc  field,  Calif.) 

IV.  Oil  and  gas  sealed  by  asphaltic  deposits. 

(Trinidad.) 
V.  At  contact  of  sedimentary  and  crystalline  rocks. 

(Some  Quebec  and  Ontario  occurrences.) 
VI.  In  joint  cracks. 

(Florence,  Colorado,  and  some  California  fields.) 
VII.  In  crystalline  rocks. 

Of  these  the  representatives  of  Group  I  are  by  far  the  most 
important. 

Mode  of  Accumulation.  —  While  the  oil  and  gas  are  not 
necessarily,  and  perhaps  rarely  are,  indigenous  to  the  rock  con- 
taining them,  a  difference  of  opinion  exists  as  to  whether  they 
have  been  transported  long  distances;  indeed  their  source  is 
often  indicated  in  some  under-  or  over-lying  bed  of  shale. 

According  to  the  original  anticlinal  theory,  the  oil,  gas,  and 
water  were  supposed  to  arrange  themselves  readily  according 
to  their  specific  gravities,  but  this  postulates  a  somewhat  free 
movement  of  these  materials  through  the  pores  of  the  rocks, 
to  which  many  modern  investigators  hesitate  to  agree. 

Capillary  action  and  great  rock  pressure  have  been  suggested 
as  possible  operating  forces,  while  Munn  believes  it  is  caused 
by  hydraulic  action.  According  to  his  hydraulic  theory  (6), 
the  diffused  oil  and  gas  are  concentrated  into  pools  or  pay 
streaks  by  the  action  of  currents  of  underground  water.  These 
collect  the  oil  and  gas  and  push  them  along.  Since  these  under- 


90 


ECONOMIC   GEOLOGY 


through  a  volcanic  neck  in  the  oil 
fields  of  Vera  Cruz  and  Tamaulipas, 
Mexico,  showing  one  mode  of  occur- 
rence of  oil  in  formations  having  a 
quaquaversal  structure.  (After  Clapp, 
Econ.  Geol.  VII.) 


ground  currents  circulating  through  the  rocks  vary  in  the  direc- 
tion of  their  flow,  there  may  be  places  where  the  meeting  of 
conflicting  currents  forms  eddies  or  places  of  no  movement. 
It  is  at  such  points  that  the  accumulated  oil  and  gas  are  held. 

If  the  water  is  flowing  through 
the  rocks  under  the  influence 
of  capillarity  alone,  and  con- 
flicting currents  are  absent, 
there  will  be  a  tendency  to 
force  the  oil  and  gas  into  the 
more  porous  beds  where  the 
capillarity  is  too  weak  for  the 
water  to  follow. 

The    pressure    of    the  oil  is 

ascribed  to  the  expansive  force 

f  . 

°*  the-  gas,  which  cannot  dif- 
fuse because  of  the  saturation 

of  the  surrounding  rocks.     The  association  of  oil  with  anticlines 

is    thought    to    be    due   to  the  influence  which  these  structures 

exert  on  the  water  currents.     The  difference  in  specific  gravity 

of  oil  and  water   is    considered   insufficient   to   account  for  the 

widespread      movement 

of  oil  against   the   fric- 

tion   developed    by    its 

passage     through    rock 

pores. 

The   oil   and  gas  are, 

then,  held   in  the  rock, 

not   because  of  an  im- 

pervious  cap   rock,  but 

by   the     overlying     and 

Surrounding    Water  man- 
j.j 

Washburne      (I2c),     in 

discussing   the  effect  of 

capillary  action,   points 

out  that  the  force  drawing   liquids    into  pores    varies  directly 

as  the  surface  tension   of  the  liquid   and  inversely  as  the  di- 

ameter  of  the  pore.      Water  having   a   greater   surface  tension 

than  oil,  capillary  action  will  exert   a  greater  pull  on  it,  and 

there  will  be  a  tendency  to  draw  it  into  the  finest  openings  and 


>  ^2.  —  Hypothetical  section  in  same  district 
as  Fig.  31,  showing  a  second  and  probably 
less  common  mode  of  occurrence  of  oil  in 
quaquaversal  structures.  (After  Clapp,  Econ. 

<&»*••  vn.) 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    91 

displace  oil  or  gas.     This  results  in  concentrating  the  last  two 
in  the  coarsest  spaces  available. 

Surface  tension  collects  the  small  bodies  of  oil  and  gas  in  a  sand 
into  larger  ones,  which  in  case  of  gas  are  capable  of  gravitative 
displacement  by  water,  so  that  the  gas  is  lifted  to  the  highest 
position  it  can  reach.  If  circulatory  movements  of  the  water 
bring  oil  to  the  water-gas  surface,  it  is  held  there  by  surface 
tension,  and  the  mass  of  oil  may  grow  by  accretion.  It  is  claimed 
that  in  the  absence  of  such  conditions,  oil  might  accumulate 
below  water  as  it  does  in  some  fields. 


Yield  of  Sands.  —  The  yield  of  an  oil  sand  depends  on  the  porosity, 
of  saturation  and  quantity  extractible.  Washburne  uses  a  saturation  factor 
of  15  per  cent  for  the  average  oil  sand,  but  assumes  that  only  75  per  cent  of 
the  sand  in  a  large  pool  is  saturated  and  that  only  60  to  75  per  cent  of  this  can 
be  recovered.  The  last  two  factors  must  be  varied  to  suit  conditions. 
The  figures  given  above  mean  524  barrels  of  oil  per  acre  foot,  which  is  high. 
The  yield  per  acre  foot  calculated  for  example,  by  Washburne,  for  the  dif- 
ferent sands  of  the  Midway,  California,  field  ranges  from  32  to  1020. l 

It  is  a  difficult  matter  to  estimate  closely  the  average  yield  of  oil  in  any  field. 
Life  of  a  Well.  —  This  may  vary  with  the  amount  of  supply,  compactness 
of  pay  sand,  and  gas  pressure  accompanying  the  petroleum.  It  varies  from 
a  few  months  to  20  years  or  more.  Some  wells  may  gush  forth  tremendous 
quantities  of  oil  and  gas  for  a  short  period  and  then  die  down  to  almost 
nothing.  Others  may  yield  moderate  quantities,  or  perhaps  only  a  few 
barrels  daily,  for  a  period  of  years.  The  average  life  of  Pennsylvania  wells 
is  seven  years. 

In  all  fields  the  production  increases  at  first  and  then  begins  to  drop  off, 
and  the  increasing  production  of  the  United  States  is  due  to  the  discovery 
and  development  of  new  fields,  whose  production  more  than  offsets  the 
decrease  of  the  older  ones. 

As  examples,  the  daily  average  production  per  well  per  day  of  New  York 
and  Pennsylvania  has  fallen  from  a  maximum  of  207  barrels  to  1.7  barrels. 
The  West  Virginia  production  has  dropped  to  56  per  cent  of  its  maximum, 
and  Ohio  and  Indiana  have  shown  a  still  greater  decline. 

On  the  other  hand,  Oklahoma  and  California  are  still  increasing  their 
output. 

Arnold  in  1915  has  figured  the  probable  future  supply  from  the  United 
States  and  Alaska  at  5,763,100,000  barrels.' 

Distribution  of  Petroleum  in  the  United  States  (PL  X).  —The 
fields  as  figured  by  Arnold  in  1915  together  with  their  proven 
areas  and  per  cent  exhaustion  are  as  follows: 

1  Johnson  and  Huntley,  Principles  of  Oil  and  Gas  Production,  1916. 


92  ECONOMIC   GEOLOGY 

PROVEN    PER  CENT 
STATE.  AREA.       EXHAUST. 

Appalachian1    ....     N.  Y.-Pa '".    .  1400  85 

W.  Va .     .  350  55+ 

Ky.-Tenn.       .....:..-  100  47 

Ohio      .     .     .     ...     ....     .  115  67 

Ohio-Indiana     ....     Ohio      .     .     .  "i     ....     .       535 

Indiana      ....    .     .     .     ..    .-      500  83+ 

Illinois          .     .     .     :    .     ....      400  36+ 

Mid-Continental    .     .     .     Kansas  .     ...     .  \    .     .     .         70  42 

Oklahoma 297  22 

Gulf Louisiana  .........         87  34 

Texas    .     ....     .     ./  .     .         50  33+ 

California    ..................     156  24 

Colorado      ....,.<.-.•     .     .     .     .     .     .         17  33£ 

Michigan     ..................  1  58 

Wyoming     ..................         31  2 

Alaska N     15  0 

1  Arnold,  Econ.  Geol.,  X,  1915. 

These  figures  of  course  represent  only  the  areas  actually  under- 
lain by  known  pools,  and  not  the  entire  area  of  the  field. 

Appalachian  Field.  —  This  is  the  largest  oil  field  in  the  United 
States,  and  includes  portions  of  New  York,  Pennsylvania,  Ohio, 
West  Virginia,  Kentucky,  and  Tennessee. 

The  rocks  are  chiefly  sandstones,  with  a  few  limestones,  embedded 
in  and  underlain  by  a  great  thickness  of  shales,  while  below  these 
are  probably  limestone  beds.  The  sandstones  have  a  thickness  of 
probably  2000  feet  or  more,  and  in  the  middle  and  northern  end  of 
the  field  range  from  the  Conemaugh  series  nearly  to  the  base  of  the 
Devonian,  and  still  lower  in  Tennessee  and  Kentucky.  Their 
deposition  represents  a  period  of  continuous  sedimentation,  with 
the  exception  of  the  period  between  the  Mauch  Chunk  and  the 
Pottsville,  where  an  unconformity  indicates  an  interval  of  uplift 
and  erosion. 

It  may  be  said  of  the  Appalachian  field  as  a  whole  that  the  oil- 
bearing  rocks  occupy  the  bottom  and  west  side  of  a  large  structural 
trough,  whose  rim  passes  through  central  Ohio,  then  eastward  south 
of  the  Great  Lakes  and  then  south  along  the  western  base  of  the 
Appalachians.  It  therefore  crosses  western  Pennsylvania  where 
petroleum  has  been  found  in  large  quantity.  While  the  total  area 
outlined  is  probably  over  50,000  square  miles,  the  area  actually  un- 


94 


ECONOMIC   GEOLOGY 


derlain  by  known  oil-bearing  sands  does  not  appear  to  exceed  3500 
(53). 

Within  this  great  trough  there  are  a  number  of  subordinate  folds 
whose  trend  is  northeast  southwest,  while  still  minor  ones  are  found 
with  their  axes  at  right  angles  to  these. 


1  Starbrick  Well 

2  Conway  Well 

3  Bradys  Bend  Well 

4  Smith  Well 

5  Bedell  Well 
GCasemanNo.lWell 


FIG.  33. — Map  showing  lines  of  sections  in  Plate  XI. 

The  sandstones  are,  moreover,  found  at  increasing  depths  as  one 
goes  southward,  so  that  those  outcropping  in  Ohio  and  New  York 
may  be  2000  or  3000  feet  below  the  surface  in  southwestern  Pennsyl- 
vania or  West  Virginia. 

In  this  region  there  are  a  number  of  sandstones,  the  important 
ones  individually  underlying  many  square  miles.  These  sand- 
stones are  most  numerous  and  attain  their  greatest  thickness  in  the 
center  of  the  region. 

The  upper  or  younger  sands  are  usually  white,  and  may  be 
conglomeratic  locally,  while  the  older  beds  are  brown  or  reddish, 
and  generally  more  uniform  in  texture. 

At  some  localities  two  or  more  sands  produce  oil,  and  the  lowest 
then  may  be  the  most  prolific.  The  wells  range  in  depth  from  10G 
to  4000  feet. 

The  character  of  the  oil  found  in  this  region  is  said  by  Dr.  Day 
to  differ  essentially  from  any  other  petroleum  thus  far  found  in  the 
world.  It  is  practically  free  from  sulphur  and  usually  from  asphalt,. 


PLATE  XI 


I 

1 


II 

tnV 


V 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    95 


but  is  rich  in  paraffin  wax.  Added  to  this  is  its  easy  conversion 
into  lamp  oil,  of  which  product  it  yields  the  greatest  percentage, 
being  far  ahead  of  all  others  except  the  Lima  and  Ohio  petroleums, 
which,  however,  are  more  expensive  to  refine. 

The  Kentucky  and  Tennessee  product,  while  inferior  to  that 
found  in  Pennsylvania,  is  much  better  than  the  Russian  or  any 
other  of  the  foreign  products  with  which  it  has  to  compete. 


I  i|^  I  Dry  oil  sand 
IjHH    Oil  accumulation 
^IwSx   Gas  accumulation 


FIG.  34. — Diagrammatic  section  of  sands  in  the  central  Appalachian  region.     (After 
Griswold  and  Munn,  U.  S.  Geol.  Sun.,  Bull.  318.) 

The  Appalachian  region,  however,  has  passed  the  zenith  of  its 
production,  that  of  Pennsylvania  having  been  reached  seven- 
teen years  ago;  and  yet  some  of  the  wells  show  a  remarkably 
persistent,  though  small,  production. 

In  New  York  State  petroleum  is  obtained  from  the  fine-grained 
sandstones  of  Chemung  age  in  parts  of  Cattaraugus,  Allegany,  and 
Steuben  counties.  The  wells  range  from  600  to  1800  feet  in  depth, 
and  while  of  small  capacity,  they  yield  a  product  of  good  quality, 
which  ranges  from  amber  to  black  in  color. 

The  petroleum-producing  belt  extends  across  Pennsylvania,  in  a 
southwesterly  direction,  leaving  it  in  the  southwestern  corner. 
Within  this  area  (whose  general  structure  has  been  referred  to  above) 
there  are  a  number  of  oil  pools,  occurring  in  rocks  ranging  from  the 
Conemaugh  series  of  the  Carboniferous  down  to  and  including  the 
Chemung  division  of  the  Devonian.  In  the  space  permitted 
here,  it  is  not  possible  to  go  into  detail  regarding  all  the  pools. 


96 


ECONOMIC  GEOLOGY 


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PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS     97 


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Ragland  oil  sand. 
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|  Clinton  (Morgan  Co.). 

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Upper  Sunnybrook. 
Deep. 
Shallow. 

Lower  Sunnybrook. 
Lower  sands  of 
Barren  } 
Wayne 
Clinton  \  Counties. 
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land  j 
Deep  sand 
(Wayne  Co.). 

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98 


ECONOMIC  GEOLOGY 


Suffice  it,  therefore,  to  say,  that  the  oil  is  obtained  from  a  num- 
ber of  different  sands,  some  of  which  are  of  high  importance, 
as  the  Berea,  Hundred  Foot,  Fifth,  etc. 

Although  the  Appalachian  field  is  on  the  wane,  some  new 
po'ols  are  being  discovered  in  West  Virginia  (56,  57),  central 
Ohio  (39a  and  6)  and  Kentucky  (32,  32a),  but  no  definite  results 
have  been  obtained  in  Tennessee  (48a) . 

In  recent  years  the  Bremen  field  (396)  of  southeastern  Ohio 
has  become  of  interest  and  importance,  because  of  its  yield  of 
oil  from  the  Clinton  sandstone  (39a).  This  formation  dips 
southeasterly,  but  there  are  occasional  reversals  of  dip,  which 
develop  local  basins,  in  which  according  to  Bownocker,  the  oil 
occurs.  The  sand  is  dry  and  has  a  thickness  of  about  30  feet. 

In  the  table  given  on  pp.  96  and  97,  an  attempt  has  been  made 
to  show  the  oil  (and  gas)  sands  known  in  the  different  formations, 
but  they  are  correlated  only  so  far  as  occurring  in  the  same 
formation.1 

Ohio-Indiana  Field  (24-26,  39-44).  — The  discovery  of  oil  and 
gas  in  the  Trenton  rocks  of  western  Ohio  in  1884  caused  consider- 
able excitement,  since  it  showed  the  existence  of  petroleum  in  lime- 
stone, an  exception  to  previously  known  conditions,  and  at  a  much 
lower  geological  horizon  than  any  in  which  oil  or  gas  had  hitherto 
been  found.  This  field  extends  from  Findlay  in  northwestern  Ohio 
southwestward  into  Indiana. 


TRENTON                       UTICA                      HUDSON  R.  NIAGARA  LIMESTONE  LOWER  UPPER                           OHIO 

LIMESTONE                    SHALE                         SHALE               NIAGARA  SHALE  HELDERBERG  HELDERBERG  SHALE 

MEDINA  CLINTON  LIMESTONE  LIMESTONE  LIMESTONE 
SHALE 


FIG.  35.  —  Geological   section   of   Ohio-Indiana  oil  and   gas  fields. 
U.  S.  GeoL  Surv.,  8th  Ann.  Kept.,  II.) 


(After  Orion, 


Most  of  the  Trenton  oil  has  been  found  in  the  upper  50  feet  of  the 
formation,  in  one  of  two  thin  streaks;  but  at  several  localities  in  both 

1  These  tables  are  those  given  by  the  respective  state  surveys. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS    99 

Ohio  and  Indiana,  a  productive  horizon  lying  from  100  to  200  feet 
deeper  has  been  discovered.  The  oils  of  this  field  contain  sufficient 
sulphur  to  require  special  treatment  for  its  elimination,  but  the  oil 
is  of  paraffin  base  like  that  of  the  Appalachian  region. 

Outside  of  the  main  field,  oil  has  been  found  in  the  Clinton  for- 
mation of  Ohio,  the  most  important  occurrence  being  in  Vinton 
County  (39).     In  Indiana  oil  has  been  obtained  from  the  Cornif- 
erous  limestone  (Devonian)  and  from  the  Huron  sandstone  (Lower 
Carboniferous)  in  Gibson  County.     The  latter  occurrence  is  ex- 
ceedingly pockety,  and  the  oil,  which  is  darker  and  thicker  than 
the  Trenton  oil,  has  a  low  percentage  of  illuminants. 

Ohio  and  Indiana  show  a  much  smaller  production  than 
formerly. 

Illinois  Field  (23,  23a  and  6).  —  Oil  and  gas  have  been  known 
in  Illinois  for  some  years,  but  the  important  discoveries  were 
not  made  until  1904,  and  the  production  since  then  has  in- 
creased at  such  a  rapid  rate  that  in  1913  it  ranked  third  .in 
the  list  of  producing  states. 

The  oil  fields,  of  which  there  are  two — the  eastern  and  the 
western,  are  associated  with  the  spoon-shaped  basin  of  the 
Eastern  Interior  Coal  Region.  On  the  eastern  slope  of  this 
syncline  is  a  somewhat  persistent  ridge,  the  La  Salle  anticline, 
whose  extension  is  traceable  across  southwestern  Indiana  to 
Hartford,  Ky.,  and  it  is  in  this  arch  that  the  sands  have  proved 
very  productive,  especially  in  Clark,  Crawford,  and  Lawrence 
counties,  a  distance  of  about  66  miles.  Seven  sands,  ranging 
from  450-1985  feet  in  depth,  are  known  in  Lawrence  County. 

On  the  western  slope  there  are  a  number  of  separate  anti- 
clines, which  have  yielded  oil  at  a  number  of  points  from  Morgan 
to  Jackson  Counties  (Fig.  35) . 

The  principal  horizons  at  which  oil  and  gas  have  thus  far 
been  discovered  are  in  the  Carboniferous  rocks,  the  sands  occurring 
in  both  the  Upper  and  Lower  Coal  Measures,  the  Potts ville 
group,  and  the  Birds  ville  and  Tribune  of  the  Mississippian. 

Most  of  the  Illinois  oils  are  above  30°  B.,  have  a  paraffine 
base,  and  are  essentially  free  from  sulphur.  The  average  gasoline 
content  is  15  per  cent. 

In  general  the  depth  of  the  wells  increases  from  north  to 
south  as  follows:  Oilfield  pool,  300-350;  Siggins  pool,  400  and 
570;  Johnson  township,  470  and  610;  Crawford  County,  900 
to  1000;  Lawrence  County,  950,  1300,  1500. 


ECONOMIC  GEOLOGY 


-L-r -A)        J 

I      DEW1TTX/       !/  }      I  * 

-^          MpA 


f—^l  GALLA^N 

WILLIAMSON       SALINE   ,  / 


iP^-^TJ 

ILLINOIS  OIL 
AND  GAS  FIELDS 

1.  Plymouth  oil  field  i  |      CL|N-/ON     I    MARION    I 

2.  Pike  County  gas  field  /  v/^_J 

3.  Jacksonville  gas  field  *  /\8  T.  C  L  A  ,  R  I  /^« 

4.  CarlinviUe  oil  and  gas  field  J  V. 

5.  Litchfield  oil  and  gas  field* 
«.  Greenville  gas  field 

7.  Carlyle  oil  field 

8.  Sparta  oil  and  gas  field* 

9.  Sandoval  oil  field. 
10.  Main  oil  fields 

IL  Allendale  oil  field 
12.  Stannton  oil  and  gae  field 
*  abandoned 


SCALE  OF  MILES 


0        10       20       30       10       50  100 

FIG.  36.  —  Map  of  Illinois  showing  distribution  of  oil  fields.     (After  De  Wolf.) 


The  Illinois  field  is  no  longer  included  in  the  Ohio-Indiana 
region,  because  the  oils  are  of  different  horizon.  Moreover,  the 
product  carries  less  sulphur  and  much  of  it  is  refined  without 


PLATE  XII 


FIG.   1.  —  General  view  of  Tuna  Valley,   in   Pennsylvania   oil   field.     (Photo,  by 

F.  H.  Oliphant.) 


FIG.  2.  —  View  in  Los  Arigeles,  Cal.,  oil  field.     Such  close  spacing  of  oil  derricks 
tends  to  hasten  the  exhaustion  of  the  oil  supply. 

(101) 


102  ECONOMIC  GEOLOGY 

special  treatment.  Some  of  it  contains  asphalt  as  well  as  paraffin, 
and  the  oils  vary  within  wide  limits  of  gravity  and  distillation 
products. 

Mid-Continental  Field  (28,  45,  45a-d) .  —  This  region  underlies 
a  portion  of '  southeastern  Kansas  and  northeastern  Oklahoma, 
and  extends  roughly  from  Paola,  Kansas,  to  Colgate,  Oklahoma. 
The  Pennsylvanian  rocks  which  outcrop  in  this  area  dip  west- 
ward in  Kansas,  and  in  northern  Oklahoma  from  50  feet  per 
mile,  to  less  than  20  feet  per  mile,  as  they  are  followed  to  the 
west,  but  in  the  southern  part  of  the  field  they  appear-  to  be 
folded  into  anticlines  and  synclines.  Three-fourths  of  the  oil 
has  come  from  the  Cherokee  formation  at  the  base  of  the  Pennsyl- 
vanian, a  little  from  the  Fort  Scott  Limestone  member  above 
it,  and  in  the  western  part  of  the  field  the  beds  still  higher  in 
the  section  have  yielded  oil. 

The  sands  outcrop  in  southeastern  Kansas  and  eastern  Okla- 
homa are  300  to  800  feet  deep  in  Nowata  County,  1200  to  2000 
near  Bartlesville  and  Tulsa,  and  2700  feet  in  the  Cleveland 
Pool. 

The  sands,  which  are  usually  lenticles  capped  by  shale  and 
sometimes  limestone,  may  vary  from  20  to  100  feet  in  thick- 
ness, and  while  there  are  usually  not  more  than  one  or  two  in 
a  pool,  the  Glen  Pool,  one  of  the  most  important,  contains  at 
least  four. 

Most  of  the  Kansas  oils  are  asphaltic,  but  in  Oklahoma  oils 
of  both  asphaltic  and  paraffin  types  are  found,  those  from  near 
Muskogee  resembling  the  Pennsylvania  oils. 

This  field  is  the  second  largest  producer  in  the  United  States, 
but  the  output  is  supplied  mainly  by  Oklahoma. 

California  (15-20).  —  While  all  the  commercially  productive 
oil  fields  lie  in  the  southern  half  of  the  state,  along  the  flanks 
of  the  Coast  Ranges,  they  are  divisible  unto  two  groups  (Fig. 
37)  as  follows:  (1)  Valley  districts,  including  the  Coalinga, 
Lost  Hills,  McKittrick,  Midway,  Sunset,  and  Kern  River;  and 
(2)  coast  districts,  lying  on  the  west  flank  of  the  Coast  Ranges, 
and  including  Santa  Maria,  Summerland,  Santa  Clara  Valley, 
Los  Angeles,  Puente  Hills,  and  others. 

The  oil  is  found  at  one  or  another  place  in  every  important 
geologic  horizon  from  the  Chico  of  the  Upper  Cretaceous  to  the 
Fernando  of  the  Pliocene,  and  the  structure  is  quite  varied. 
In  the  San  Joaquin  Valley  districts  the  oil  is  generally  associated 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS   103 


with  monoclines,  but  in  the  coastal  counties,  anticlines  and 
faults  are  more  effective  factors  of  accumulation.  Sandstones 
commonly  form  the  reservoir  rock,  but  exceptionally,  as  in  the 
Santa  Maria  field,  the  oil  occurs  in  cracks  in  hard  flinty  shales 
or  in  the  pores  of  softer  ones. 


MAP  OP 

A  PORTION  OF 

CALIFORNIA          *«»™^ 

Showing  Pipe  Lines  and  Oil  Districts 
SCALE  OF  MILES 


0     10     -JO  40  GO  80 


FIG.  37.  —  Map  of  California  oil  fields  and  pipe  lines.     (After  Arnold  and  Garfias, 
Amer.  Inst.  Min.  Engrs.,  Bull.  87,  1914.) 

Where  the  oil  sand  outcrops,  it  is  often  sealed  by  asphalt. 

Arnold  believes  that  the  oil  has  been  derived  from  both  animal 
and  vegetable  matter,  but  chiefly  diatoms. 

Nearly  all  of  the  California  oils  have  an  asphalt  base,  and 
about  40  per  cent  of  the  output  is  heavy  oil,  used  for  fuel  or 
road  dressing,  while  the  remaining  60  per  cent  is  refined,  the 
residuum  being  used  for  fuel. 


104 


ECONOMIC   GEOLOGY 


In  the  Kern  River  field,  which  is  the  most  important,  the  well  records 
indicate  a  great  body  of  Miocene  (Tertiary)  sands  and  clays  in  which  the 
general  westerly  dip  away  from  the  Sierra  granites  has  been  locally  inter- 
rupted by  anticlines,  on  the  flanks  of  which  the  oil  has  been  found. 

The  oil  occurs  in  sands  interbedded  with  the  clays  which  underlie  one 
heavy  clay  bed  and  overlie  another.  The  thickness  of  the  oil-bearing  sands 
may  vary  from  200  or  300  to  400  or  500  feet. 

The  Santa  Maria  field  comprises  the  Santa  Maria,  Lompoc,  and  Cat 
Canyon  fields,  in  northern  Santa  Barbara'  and  southern  San  Luis  Obispo 
County.  The  formations  involved  in  the  productive  region  range  from 
Lower  Miocena  to  Quaternary,  involving  beds  of  shale,  sandstone,  diatoma- 
ceous  earth,  and  volcanic  ash. 

The  region  contains  long  sinuous  folds  of  a  peculiar  type,  and  most  of 
the  wells  arc  located  along  or  near  anticlines,  ranging  in  depth  from  1500 


FIG.  38.  —  North-south  section,  showing  structure  of  western  field  of  Los  Angeles 
district.     (After  Eldridge  and  Arnold,  U.  S.  Geol.  Sun.,  Bull,  309.) 

to  over  4000  feet.  In  the  Santa  Maria  and  Lompoc  fields  the  oil  is  ob- 
tained from  zones  of  fractured  shale,  or  sandy  layers  in  the  lower  portion 
of  Monterey  (Middle  Miocene),  and  has  an  average  gravity  of  25°  B. 

Although  the  Kern  River  field  leads  in  point  of  production,  the  Santa 
Maria  leads  in  the  production  per  well,  and  supplies  most  of  the  oil  exported, 
its  situation  giving  it  command  of  the  coast  trade  from  Alaska  to  Chile, 
as  well  as  foreign  trade  with  Japan  and  Hawaii. 

The  Summerland  field  is  of  interest,  for  the  reason  that  Arnold  believes 
the  oil  to  have  been  derived  from  diatoms  (19),  and  other  organisms  found 
in  the  Monterey  shale.  It  has  subsequently  migrated  upward  into  the 
overlying  Fernando,  and  to  some  extent  Pleistocene  formations,  urged  along 
probably  by  gas  or  hydrostatic  pressure.  A  similar  origin  is  also  ascribed 
to  the  oil  in  the  Coalinga  district. 

The  California  oils  are  generally  characterized  by  much  asphalt  and  little 
or  no  paraffin,  although  in  recent  years  there  has  been  a  considerable  yield 
of  lighter  grade  oils  from  the  Santa  Maria  and  Monterey  districts.  Since 
these  are  well  adapted  to  refining,  they  will  probably  be  in  strong  demand. 


106 


ECONOMIC  GEOLOGY 


Texas-Louisiana  Oil  Fields  (34,  35,  49-51).  — This  includes  a 
series  of  small  scattered  fields  lying  mostly  in  the  coastal  plain 
region  of  Texas  and  Louisiana  (PL  X).  Underlying  the  coastal 
plain  there  is  a  series  of  Quaternary,  Tertiary,  and  Cretaceous 
clays,  sands,  and  gravels,  with  occasional  limestones,  having 
in  general  a  gentle  southeastern  dip,  interrupted  by  low 


LEGEND 


m 

SAND 


m 

SHALEj 


SALT        DOLOMITE        CLAY  SAND  SHALE.,       GYPSUM. 

FIG.  39. — Section  of  Spindle  Top  oil  field  near  Beaumont,  Tex. 

Min.  Mag.,  XL) 


(After  Fenneman, 


domes,  which,  in  parts  of  Louisiana  at,vteast,  appear  to  be 
due  to  the  upthrust  caused  by  the  growth  of  salt  and  gypsum 
masses. 

Under  these  domes,  or  mounds,  and  underlying  the  sediments 
mentioned  above,  there  are  usually  found  deposits  of  marly  or 
crystalline  limestone  (often  dolomitic),  sulphur,  gypsum,  and 
rock  salt,  which  in  most  cases  are  at  considerable  depth,  but 
occasionally  lie  at  or  near  the  surface.  Thus  at  Avery  Island, 
Louisiana,  the  heavy  deposit  of  rock  salt  comes  within  15  feet 
of  the  surface,  but  at  Spindle  Top,  Texas,  the  limestone  is  800 
or  900  feet  deep. 

The  oil  is  most  frequently  found  in  or  near  the  lime- 
stones. 

The  oil  pools  a.re  of  small  size,  and  that  discovered  at  Beau- 
mont, Texas,  may  serve  as  a  type  of  many.  This  pool,  which 
covers  an  area  of  about  200  acres  (PL  XIII),  was  discovered  in 
1901,  and  within  a  year  and  a  half  280  successful  wells  had  been 
drilled.  The  oil  rock,  which  lies  from  900  to  1000  feet  below 
the  surface,  is  a  very  porous,  crystalline,  dolomitic  limestone, 
and  the  cap  rock  is  clay.  The  m occurrence  of  gypsum  and  salt 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  107 


underlying  the  oil  rock  in  some 
of  the  wells  is  unique  (Fig.  39). 
Many  of  the  wells  in  this  pool 
were  gushers,  but  so  great  was  the 
drain  on  this  field  that  by  the 
end  of  the  first  year  after  its 
discovery  the  pressure  was  con- 
siderably reduced,  and  in  1903 
many  of  the  wells  had  practically 
ceased  producing,  while  others 
were  yielding  a  mixture  of  salt 
water  and  oil.  The  production, 
however,  is  still  considerable, 
although  the  supply  is  no  doubt 
exhaustible.  The  coastal-plain 
oils  have  an  asphaltic  base,  or 
are  "  heavy,"  and  at  times  con- 
tain considerable  sulphur. 

In  1903  many  wells  were 
being  developed  in  the  Sour 
Lake  district  about  20  miles 
northwest  of  Beaumont.  The 
oil  is  heavy  like  that  of  Beau- 
mont, but  runs  lower  in  sulphur. 
In  Louisiana  active  drilling  oper- 
ations have  been  carried  on  in 
the  region  around  Jennings,  and 
one  well  yielded  20,000  barrels 
per  day  while  it  was  gushing. 
The  oil  resembles  that  of  Beau- 
mont. 

The  belt  of  Cretaceous  rocks 
of  central  Texas  has  yielded  both 
oil  and  gas  at  several  localities, 
but  the  only  important  one  is 
at  Corsicana,  where  both  a 
light  and  heavy  oil  have  been 
found  in  sands  interbedded  with 
dense  clay  shales.  The  two 
kinds  of  oil  occur  at  different 
horizons. 


\ 
A 

// 
^JL 


6 

31 


108 


ECONOMIC  GEOLOGY 


In  northwestern  Louisiana,  both  oil  and  gas  are  found  in  the  more  or 
less  consolidated  Cretaceous  rocks,  which  underlie  the  Tertiary  and  Quater- 
nary. Here  the  Cretaceous  rocks  which  dip  to  the  southward  show  a  dome- 
like uplift  of  considerable  dimensions,  which  brings  them  within  700  feet 
of  the  surface.  This  includes  the  Caddo  field,  and  although  the  oil  and 
gas  occur  separately  or  together  at  four  horizons,  viz.  the  Nacatoch, 
Austin,  Eagle  Ford,  and  Woodbine,  of  the  Upper  Cretaceous,  most  of  the 
gas  is  obtained  from  the  first  or  upper,  and  the  oil  from  the  fourth  or  lower 
division.  The  main  oil  sand  is  about  2200  feet  deep.  The  oil  from  this 
field  is  light,  similar  to  that  of  the  Appalachian  region,  and  thus  differs 
strongly  from  the  Beaumont  and  Jennings  oils  (Harris). 

Most  of  the  oils  of  the  Gulf  region  contain  considerable  quantities  of  sul- 
phur, largely  in  the  form  of  hydrogen  sulphide,  and  therefore  easily  removed 
by  steam  before  refining,  or  for  use  as  fuel.  They  make  a  good  fuel  oil, 
which  because  of  the  location  of  the  field  can  be  easily  exported,  but  they 
also  yield  a  good  grade  of  lubricating  oil.  Moreover,  the  gasolene  derived 
from  them  is  acceptable  as  a  substitute  for  turpentine. 

The  Corsicana  and  Caddo  field  oils  are  lighter  and  run  lower  in  sulphur. 

Colorado.  —  Florence  (21)  and  Boulder  (22)  are  the  two  important 
oil-producing  localities.  At  the  former  the  oil  is  found  in  beds  of 
Cretaceous  age,  at  depths  of  from  1000  to  2000  feet,  and,  unlike 
many  occurrences,  appears  to  have  accumulated  in  fissures,  although 
the  rocks  of  the  region  as  a  whole  form  a  syncline. 

At  Boulder,  the  oil  is  found  associated  with  broad  low  anticlines  in 
sandstones  and  shales  of  the  Pierre  (Cretaceous)  formation,  and  is 
now  being  obtained  at  depths  ranging  from  2100  to  2350  feet.1  The 
oil  does  not  vary  much  in  quality. 


FIG.  41. — Map  of  Wyoming,  showing  approximately  the  areas  underlain  by  oil  and 

gas.     (After  Day.) 
1  R.  D.  George,  private  communication. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  109 

Wyoming  (58-63) .  —  This  state  contains  a  number  of  oil  and 
some  gas  districts  (Fig.  41),  most  of  which  are  but  slightly 
developed.  The  oil  is  obtained  chiefly  from  the  Cretaceous, 
and  many  of  the  occurrences  appear  to  be  associated  with  anti- 
clines (62),  but,  in  one  field  (Spring  Valley,  Uinta  County) 
at  least  (63),  the  oil  occurs  in  a  synclinal  basin  (Fig.  42),  whose 
bounding  fault  on  the  northwest  seems  to  have  permitted  some- 
what abundant  seepage. 

The  oils  vary  in  their  gravity,  but,  according  to  published 
data,  are  mainly  of  medium  gravity. 


.«  SECTION  X-X 

*   -  -          § 


Feet 
8000 
6000 
4000 
2000 
Sea  Level 


Ifisa  137  I*  i 

iSIiiHiiJ 


II 


Feet 


6000 
4000 
2000 


.Level 


SECTION  Y-Y 

FIG.  42. — Section  across  portion  of  oil  district  of  southwestern  Wyoming.     (After 
Veatch,  U.  S.  Geol.  Surv.,  Prof.  Pap.  56.) 


The  Salt  Creek  field  is  the  most  important  producer,  its  prod- 
uct being  piped  to  Casper  for  refining. 

Alaska  (14).  —  Oil  has  thus  far  been  found  in  Alaska  at  only 
four  localities,  at  which  the  indications  were  sufficient  to  warrant 
drilling.  Wells  have  been  driven  at  three,  and  disclosed  the  presence 
of  oil  similar  to  that  of  Pennsylvania.  All  of  the  fields  lie  in  the 
Pacific  coast  region,  but  none  have  been  extensively  developed,  as 
the  low  price  of  imported  oil  and  high  cost  of  drilling  in  Alaska  have 
discouraged  attempts  towards  development. 

In  the  Katalla  field,  located  near  the  mouth  of  the  Copper  River, 
the  oil  is  found  in  complexly  folded  and  faulted  Tertiary  shales  and 
sandstones.  At  Cook  Inlet,  folded  and  faulted  Jurassic  shales  and 
sandstones  form  the  petroliferous  horizon.  At  Cold  Bay,  where 
seepages  are  found  as  in  the  other  fields,  the  structural  conditions 


110 


ECONOMIC   GEOLOGY 


and  age  of  the  oil-bearing  strata  are  similar  to  those  at  Cook  In- 
let. Seepages  are  found  in  Tertiary  rocks  near  Cape  Yakataga, 
but  no  wells  have  been  drilled. 


ifl 


43S%^ 

^l°°    k^^SHUMAGIN   IS. 
162  a  LonBilude  West  from  Orwnwich     154° 


SCALE  OF  MILES 

9     5,0   IPO         290 


FIG.  43.  —  Map  of  Alaska,  showing  areas  in  which  oil  or  gas  are  known  to  occur. 

(After  Day.) 

Summary.  —  The  following  table  summarizes  very  briefly  the 
mode  of  occurrence  in  the  several  fields: — 


SUMMARY  OF  OIL  OCCURRENCE  IN  THE  PRINCIPAL  UNITED  STATES  FIELDS 


FIELD 

STRUCTURE 

GEOLOGIC  AGE 

KIND  OF  ROCK 

KIND  OF  OIL 

Appalachian. 

Geosyncline   with 
subordinate  an- 

Ordovician       to 
Carboniferous. 

Mostly  sandstone. 

Paraffin  base. 

ticlines. 

Lima-Indiana. 

Anticlines. 

Ordovician. 

Mostly         lime- 

Paraffin base.  Sul- 

stone. 

phur. 

Illinois. 

Low  anticlines  (?) 

Carboniferous. 

Sandstones. 

Paraffin             and 

mixed  oils. 

Michigan. 

Probably       anti- 

Silurian. 

Sandstones. 

Paraffin  base. 

clines. 

M  id-Con  tinental  . 

Westerly         dip, 

Carboniferous. 

Shales,         sand- 

Both       paraffinic 

with  some  anti- 

stones mostly. 

and  asphaltic. 

clines. 

Wyoming. 

Usually  folded. 

Carboniferous  to 

Mostly  sandstone. 

Paraffinic  and  as- 

Tertiary. 

phaltic. 

Colorado. 

Folded. 

Cretaceous. 

Sandstone      and 

Paraffinic. 

shale. 

Gulf  Coast. 

Domes. 

Tertiary          and 

Dolomite        and 

Mainly  asphaltic, 

Cretaceous. 

sandstone. 

sometimes  high 

sulphur. 

California. 

Folded            and 

Tertiary. 

Sandstones, 

Mainly  asphaltic. 

faulted. 

shales,        con- 

glomerates. 

Alaska. 

Folded            and 

Jurassic  to   Ter- 

Sandstones    and 

Paraffin. 

faulted. 

tiary. 

shales. 

Canada  (63e-i). — Oil  is  obtained  in  Canada  in  Ontario, 
New  Brunswick  and  Alberta,  but  only  the  production  from  the 
first  named  is  important,  although  it  has  been  decreasing  since 
1906. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  111 

In  Ontario  the  important  wells  are  confined  to  the  Paleozoic 
rocks  of  the  area  lying  west  and  southwest  of  a  line  connecting 
Georgian  Bay  and  Toronto.  The  flat-lying  undisturbed  sedi- 
ments of  this  series  have  a  thickness  of  nearly  3800  feet  in  Lamb- 
ton  County,  but  their  thickness  decreases  as  the  pre-Cambrian 
rocks  to  the  north  are  approached.  The  oil  occurs  in  the  Onon- 
daga,  Oriskany,  Guelph,  Niagara,  Medina,  and  Trenton,  the  first 
named  being  the  most  important,  and  supplying  the  oil  in  the 
Petrolia  or  most  important  field.  The  depths  to  which  the  wells 
penetrate  vary  on  the  average  from  about  350  to  1300  feet. 

In  New  Brunswick  oil  is  obtained  from  the  Albert  shales  of  the 
Subcarboniferous. 

Considerable  prospecting  has  been  done  recently  along  the 
foothills  west  of  a  line  connecting  Calgary  and  Edmonton,  and 
while  small  quantities  of  oil  have  been  struck  here  and  there 
in  the  Dakota  sandstone,  no  large  producers  have  been  de- 
veloped. 

Mexico.1  —  The  Mexican  oil  field  is  located  in  a  rectangle  50  miles  wide 
and  160  miles  long,  extending  from  Tampico  west  to  Panuco  and  thence 
south  to  Tuxpam.  Its  growth  can  be  seen  by  the  increase  from  a  recorded 
production  of  200,000  barrels  in  1904,  to  25,725,403  barrels  in  1914.  The 
main  districts  are  Ebano,  Panuco,  Tuxpam,  and  Huasteca,  the  first-named 
being  the  oldest  and  the  last-named  the  most  important. 

The  geologic  formations  include:  (1)  Tamasopa  limestone  (Upper (?) 
Cretaceous);  (2)  San  Felipe  limestones  and  shales  (Upper  Cretaceous); 
(3)  Mendez  marls  and  shales  (Eocene);  (4)  Tertiary  limestones,  sandstones 
and  clays,  and  Pleistocene  deposits  of  no  importance  in  the  oil  occurrence; 
(5)  Igneous  intrusions  of  late  Tertiary  or  early  Quaternary,  in  the  form  of 
dikes,  sills,  or  stocks.  The  general  gentle  easterly  dip  of  the  sediments 
is  interrupted  by  domes  and  basins,  the  beds  being  also  fractured  by  joints 
and  faults.  The  intrusive  stocks  show  a  close  association  with  the  oil, 
but  the  exact  significance  of  this  is  not  settled  to  the  satisfaction  of  all, 
though  they  doubtless  by  deformation  of  the  sedimentaries  may  have  been 
an  influencing  factor  in  the  oil  accumulation. 

The  oil  in  general  seems  to  come  from  near  the  top  of  the  Tamasopa 
limestones,  but  it  may  have  originated  in  the  Mendez  marls.  It  is  usually 
heavy,  with  an  asphaltic  base,  the  thickness  sometimes  interfering  with 
its  transportation  through  pipe  lines.  Some  of  the  wells  have  shown  an 
enormous  yield.  One,  the  Juan  Casiano  No.  7,  has  been  making  about 
700,000  barrels  per  month,  with  about  40,000,000  barrels  to  its  credit,  while 
another,  the  Dos  Bocas  gusher,  blew  a  crater  in  the  ground,  and  after  pro- 
ducing 200,000  barrels  a  day  for  57  days,  went  to  salt  water. 

1  Garfias,  Econ.  Geol.,  X,  No.  3,  1915;  Ordonez,  Amer.  Inst.  Min.  Engrs., 
L:  859,  1914;  De  Golyer,  Ibid.,  Bull.  105:  1899,  1915;  Huntley,  Ibid.,  Bull.  105: 
2067,  1915. 


112 


ECONOMIC  GEOLOGY 


>  Pipe  Lines  Completed  --  -Building 
-Railroads  Completed  -H--M-  Surveyed  or  Building  f 
<  Pipe  Paralleled  by  Railroads  A 

-  Barge  Routes 


FIG.  44.  —  Sketch  Map  of  the  Mexican  Oil  Fields,  showing  Pipe  Lines  and  Rail- 
roads.    (After  Huntley,  Amer.  Inst.  Min.  Engrs.,  Bull.  105,  1915.) 


Basalt  Dike 
(Hypothetical  along 

this  section) 


FIG.  45. — Hypothetical  Section  through  the  Panuco  Field,  Mexico,  showing  anticlinal 
terrace  and  fracture.      (After  Huntley,  Amer.  Inst.  Min.  Engrs.,  Bull.  105, 1915.) 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  113 

Other  Important  Foreign  Fields.  —  Among  the  foreign  producers,  Russia 
Galicia  and  Rumania  have  contributed  considerably  to  the  world's  supply 
of  petroleum.  In  Russia,1  the  Baku  region  on  the  Apsheron  pensinula 
of  the  eastern  Caucasus,  yields  75  per  cent  of  the  country's  output.  The 
rocks  involved  are  Pliocene,  Miocene,  and  Oligocene  sediments,  with  some 
volcanic  ash,  and  the  whole  series  has  been  strongly  folded  and  faulted, 
mud  volcanoes  and  seepages  being  distributed  along  the  main  line  of  uplift. 
The  oil  series,  which  has  a  thickness  of  5000  feet,  consists  of  Miocene  clays, 
sands  and  marls.  Of  the  three  divisions  found  in  the  largest  or  Balakhany- 
Sabunchy  field,  the  upper  is  productive  with  the  wells  ranging  from  300 
to  2400  feet  in  depth.  Another  small  but  productive  district  is  the  Bibi- 
Eibat  on  the  Caspian  shore. 

In  the  Galician  2  oil  field  on  the  north  flanks  of  the  Carpathians,  the  oil 
is  obtained  from  strongly  folded  Eocene  rocks,  while  in  the  Rumanian 
field,  which  is  continuous  with  that  of  Galicia,  the  Miocene  and  Pliocene 
formations  are  the  petroliferous  ones.  The  only  other  region  producing 
over  2  per  cent  of  the  world's  output  is  the  Dutch  East  Indies,  where,  in 
southeastern  Borneo,  the  oil  is  found  in  Miocene  sandstones. 

Distribution  of  Natural  Gas  in  the  United  States.  —  The  distribu- 
tion of  gas  is  practically  coextensive  with  that  of  petroleum,  and 
most  oil  wells  yield  some  gas;  but  the  regions  from  which  supplies  are 
obtained  and  utilized  are  fewer  than  those  of  petroleum. 

Day  (53)  gives  the  following  estimate  of  the  area  in  square  miles 
of  gas  pools  in  the  several  fields. 

Appalachian Kentucky 290 

New  York 550 

Ohio 110 

Pennsylvania     ....  2730 

West  Virginia    ....  1000        4680 


Ohio     .... 

.     .     .       165 

2625 

Illinois        

50 

Michigan   

40 

Mid-Continental      .     . 

.     .     .  Oklahoma      .     . 

,     .     .     1000 

Missouri   . 

.     .     .         70 

Kansas      .     .     . 

.     .     .       550 

1620 

Colorado     

80 

Wyoming    

120 

California  

310 

Texas-Louisiana  .     .     . 

240 

Others    

290 

10,055 

1  Adiassevich,  Amer.  Inst.  Min.  Engrs.,  XLVIII:    613,  1915;    Dalton,  Econ. 
Geol.,  IV:   89,  1909. 

2  Dalton,  loc.  cit. 


114  ECONOMIC  GEOLOGY 

Natural  gas  shows  a  wide  geologic  distribution,  for  in  the 
United  States  and  Canada  it  is  found  at  one  place  or  another 
in  formations  ranging  from  Cambrian  to  Tertiary,  exclusive  of 
Jurassic  and  Triassic. 

UNITED  STATES 

The  five  most  important  natural  gas  producing  regions  are: 
(65«) :  1.  Appalachian,  including  New  York,  Pennsylvania,  south- 
eastern Ohio,  West  Virginia,  Kentucky,  and  Alabama;  2.  Ohio 
and  Indiana,  Trenton  rock  area;  3.  Clinton  sand  area  of  central 
Ohio;  4.  Mid-continental  area;  5.  Caddo  field  of  northwestern 
Louisiana. 

Appalachian  Field.  —  Gas  is  obtained  in  New  York  (74) 
from  the  Corniferous,  Guelph,  Niagara,  and  Trenton  lime- 
stones, and  from  the  Medina  and  Potsdam  sandstones.  The 
depths  range  from  150  to  3000  feet,  with  a  general  monoclinal 
structure. 

In  Pennsylvania  (78)  the  gas  lies  west  of  the  Allegheny  Moun- 
tains in  comparatively  undisturbed  strata,  the  productive  horizons 
ranging  from  the  Conemaugh  to  Middle  Devonian.  It  may 
occur  in  others  lower  down,  but  the  formations  productive  in 
New  York  lie  pretty  deep  in  Pennsylvania,  the  Corniferous  for 
example,  having  been  encountered  in  Washington  county  at  a 
depth  of  6000  feet. 

In  West  Virginia  (56)  gas  is  obtained  in  the  northwestern 
half  of  the  state  at  depths  of  from  500  to  4000  feet,  associated 
with  anticlines  and  synclines  as  in  Pennsylvania,  but,  owing  to 
the  greater  thickness  of  the  formations,  the  drill  has  not  reached 
below  the  Speechley  (Chemung)  sand. 

The  southeastern  Ohio  gas  field  is  a  continuation  of  the  West 
Virginia  one,  while  some  Devonian  gas  is  found  in  northeastern 
Ohio,  even  west  of  the  Appalachian  belt. 

Kentucky  has  productive  gas  areas  obtaining  a  supply  from 
the  Pottsville,  Berea,  Devonian  shales,  and  Trenton  limestone. 
The  supply  comes  chiefly  from  the  northeastern  portion  of  the 
state. 

Ohio-Indiana '  Fields  (67,  68,  76,  77) .  —  Gas  is  obtained  from 
the  Trenton  limestone  along  the  Cincinnati  anticline,  but  the 
supply  is  much  less  than  formerly.  Aside  from  this  the  De- 
vonian shales  and  limestone  supply  some  gas  in  southern  and 
western  Indiana. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  115 

Clinton  Sand  Area,  Ohio  (65a,  39  and  39a,  under  Oil).  —  Gas  is 
obtained  from  the  Clinton  sand  in  a  belt  parallel  with  the  Cincin- 
nati arch,  and  extending  from  western  Ontario  to  the  Ohio 
River. 

Mid-Continental  Field.  —  In  southeastern  Kansas  (70)  gas  is 
obtained  from  the  Carboniferous,  the  same  as  the  oil,  at  depths 
ranging  from  80  to  1300  feet,  while  in  Oklahoma  the  sands  of 
Carboniferous  age  are  now  strongly  productive.  The  general 
structural  features  were  referred  to  under  oil. 

Louisiana  (65«,  73) .  • —  The  Caddo  field  of  northwestern 
Louisiana,  located  on  a  broad  anticline  known  as  the  Sabine 
Uplift,  is  the  most  important  producer,  although  some  gas  is 
found  with  the  salt  domes  in  the  southern  part  of  the  state. 
The  product  is  all  from  the  Cretaceous. 

Other  Localities.  - —  Not  a  little  gas  is  obtained  from  the  dif- 
ferent oil  fields,  not  located  in  the  strata  above  mentioned,  as 
in  Illinois  and  California. 

Distribution  of  Natural  Gas  in  Canada.  —  Natural  gas  occurs 
in  Ontario  (79a-6)  in  the  Onondaga,  Guelph,  Clinton,  Medina 
and  Trenton  formations.  Less  important  occurrences  are  found 
in  the  glacial  drift.  The  most  important  area  is  the  Kent  field 
of  Tilbury  and  Romney  townships,  where  the  gas  is  obtained 
from  the  Onondaga  dolomite.  In  New  Brunswick  gas  has  been 
obtained  in  Albert  County  from  Subcarboniferous  rocks,  at  depths 
ranging  from  1200  to  2000  feet. 

In  the  western  provinces  (79c)  natural  gas  was  developed 
at  Carlstadt,  Alberta,  as  early  as  1885,  but  the  active  develop- 
ment at  Medicine  Hat,  Alberta,  began  about  1905.  At  this 
locality  gas  is  encountered  in  the  Belly  River  formation  at  about 
600  feet  depth,  but  the  main  supply  comes  from  the  Niobrara 
in  wells  ranging  from  1000  to  1300  feet,  and  having  an  open  flow 
pressure  of  two  to  three  million  cubic  feet  per  24  hours. 

The  second  important  gas  field  of  the  western  provinces  is 
around  Bow  Island,  Alberta.  Here  the  gas  is  obtained  from  the 
Dakota  formation  at  depths  of  about  2000  feet.  The  first  well 
driven  in  1909  showed  810  pounds  pressure  and  seven  million 
cubic  feet  flow.  The  gas  from  here  is  piped  to  Lethbridge  and 
Calgary. 

Gas  has  been  found  in  limited  quantities  at  a  number  of  other 
points  in  the  Great  Plains  area,  that  from  Dunmore  Junction, 
Suffield  and  Vegreville,  occurring  in  the  Niobrara  formation. 


116  ECONOMIC  GEOLOGY 

Uses  of  Petroleum.  —  The  three  most  important  uses  are  for 
light,  heat,  and  lubrication;  but  the  various  distillates  have  special 
uses.  Rhigolene  is  used  as  a  local  anesthetic,  gasoline  is  used  as 
fuel,  and  naphtha  as  a  solvent  for  resins  in  making  varnish  and  in 
oilcloth  manufacture,  while  benzine  is  of  value  for  cleaning  and  as  a 
substitute  for  and  an  adulterant  of  turpentine.  Astral  oil  and  min- 
eral sperm  oil  are  special  grades  of  illuminating  oil  with  high 
flashing  points.  Crude  petroleum  is  now  much  used  for  fuel 
purposes  in  engines,  as  along  the  Pacific  coast  and  in  the  south- 
west, where  good  coal  is  so  scarce  that  many  of  the  locomotives 
are  run  by  the  use  of  crude  oil. 

The  paraffin  residue  is  placed  on  the  market  for  medicinal  pur- 
poses under  the  name  of  vaseline,  petroleum  ointment,  and  cosmo- 
line.  It  is  also  used  as  an  adulterant  of  candy  and  for  electrical 
insulation. 

Uses  of  Natural  Gas.1 — Natural  gas  is  widely  employed  as  a  fuel 
in  factories,  metallurgical  establishments,  glass  works,  cement 
plants,  etc.  For  domestic  purposes,  such  as  heating,  cooking,  and 
lighting,  it  is  also  widely  used.  Its  cheapness,  cleanliness,  and 
high  calorific  power,  and  the  ease  with  which  it  can  be  used,  have 
been  important  factors  in  insuring  its  widespread  selection  for 
the  above  purposes.  Some  is  used  in  the  manufacture  of  carbon 
black.2 

The  term  carbon  black  as  used  in  the  trade  is  applied  to  lamp- 
black made  upon  the  surfaces  of  metal  or  stone,  by  direct  impact 
of  flame,  while  lamp  black  is  a  soot  deposited  by  the  smudge  proc- 
ess and  made  from  oil,  resin,  or  some  other  solid  or  liquid  raw 
material. 

A  profitable  industry  now  is  the  separation  of  the  more  volatile 
grades  of  gasoline  from  natural  gas  issuing  from  oil  wells.  The 
gas  from  different  regions  yields  from  0  to  8  or  10  gallons  of 
gasoline  per  thousand  feet  of  gas.3 

The  former  wasteful  use  of  natural  gas,  and  its  allowed  escape 
from  oil  wells  helped  greatly  to  deplete  the  supply  in  some  fields, 
so  that  energetic  measures  have  been  taken  to  combat  this.4 

1  Johnson  and  Huntley,  Principles  of  Oil  and  Gas  Production,  1916. 

2  U.  S.  Geol.  Surv.,  Min.  Res.  1913,  II:    1488,  1914. 

3  Bureau  Mines,  Technical  Paper  No.  10. 

«U.  S.  Geol.  Surv.,  Min.  Res.,  1911,  II:  280,  1912. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  117 


SOLID  AND   SEMI-SOLID  BITUMENS 

Under  this  heading  are  included  (1)  bitumens  of  a  more  or  less 
solid  character  which  are  found  filling  fissures  in  the  rocks,  or  some- 
times occupying  basin-shaped  depressions  on  the  surface,  and  (2) 
bitumen  of  viscous  character,  or  maltha,  which  is  found  oozing  from 
fissures  or  pores  of  the  rocks  and  sometimes  collecting  in  pools  on  the 
surface. 

Both  of  these  are  usually  of  rather  high  purity,  and  those  belonging 
to  the  first-named  group  may  have  a  rather  wide  geologic  and  geo- 
graphic (Fig.  46)  range. 


FIG.  46.  —  Map  of  asphalt  and  bituminous  rock  deposits  of  the  United  States. 
(After  Eldridge,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  IX.) 

Those  of  the  first  group  were  termed  asphaltites  by  Eldridge,  but 
since  they  are  not  all  true  asphalts,  it  seems  best  perhaps  to  avoid 
this  term.  They  are  most  commonly  found  filling  fissures,  usually 
in  sedimentary  rocks,1  and  might  perhaps  be  termed  vein  bitumens. 

Vein  Bitumens.  —  There  are  several  varieties  of  these,  all  black 
or  dark  brown  in  color,  commonly  with  a  pitchy  odor,  burning 
readily  with  a  smoky  flame,  and  insoluble  in  water,  but  soluble  to  a 

1  The  anthraxolite  of  Ontario  occurs  in  slate,  and  an  asphalt  vein  in  quartz- 
porphyry  has  been  described  from  near  Heidelberg,  Germany.  (Geol.  Zentralbl., 
XIII:  547,  1909.) 


118  ECONOMIC   GEOLOGY 

varying  degree  in  ether,  oil  of  turpentine,  and  naphtha.  Their  spe- 
cific gravity  ranges  from  1  to  1.1.  They  are  closely  related  chemi- 
cally and  in  their  mode  of  occurrence,  but  differ  somewhat  in  their 
behavior  toward  solvents,  as  well  as  in  their  fusibility,  so  that  their 
identification  is  often  somewhat  uncertain.  The  most  important 
varieties  are  described  below. 

Albertite  (91).  A  black  bitumen  with  a  brilliant  luster  and  conchoidal 
fracture,  a  hardness  of  1  to  2,  and  specific  gravity  1.097.  It  is  barely  soluble 
in  alcohol,  and  dissolves  to  the  extent  of  4  per  cent  in  ether  and  30  per  cent 
in  oil  of  turpentine. 

Some  American  occurrences  of  vein  bitumens  are  thought  to  belong 
here,  but  the  most  important  occurrence  is  at  Albert  Mines,  New  Bruns- 
wick (91)  where  a  vein  of  albertite  is  found  in  the  Subcarboniferous  shales. 
The  vein  had  a  length  of  about  half  a  mile  and  was  followed  down  its  steep 
dip  to  a  depth  of  1500  feet.  Its  thickness  varied  from  15  feet  to  zero, 
and  branch  veinlets  ran  off  into  the  wall  rock.  It  was  worked  for  thirty 
years  and  proved  to  be  one  of  the  most  profitable  mineral  industries  of  New 
Brunswick. 

Anthraxolite  (93)  is  a  coaly,  lustrous,  black  mineral,  with  a  hardness  of  3  to 
4,  and  specific  gravity  of  1.965.  It  is  found  at  Sudbury,  Ontario,  forming 
veins  in  a  black  fissile  slate,  but  has  also  been  described  from  other 
localities. 

Ozokerite  (98,  106),  also  termed  mineral  wax  or  native  paraffin,  is  a  wax- 
like  hydrocarbon,  yellow  brown  to  green,  translucent  when  pure,  and  of 
greasy  feel.  Its  specific  gravity  ranges  from  .845  to  .97.  It  is  easily  soluble 
in  petroleum,  benzine,  benzole,  turpentine,  and  carbon  disulphide,  but 
more  difficultly  so  in  ether  and  ethyl  alcohol. 

It  is  known  to  occur  in  Utah  (106)  where  the  material  is  found  filling 
fissures  in  zones  of  crushed  Tertiary  shales,  sandstones,  and  limestones, 
near  Midway,  Soldiers  Summit,  and  Coulters 'station  on  the  Rio  Grande  and 
Western  Railway.  The  conditions  are  not  regarded  as  very  favoraple 
for  working.  The  most  important  deposit  of  Ozokerite  is  in  Galicia.  There 
it  is  found  forming  veins  from  a  few  millimeters  up  to  several  feet  in  thick- 
ness, in  much-disturbed  Miocene  shales  and  sandstones. 

Grahamite  (97,  105,  108).  —  This  has  a  hardness  of  2,  and  a  specific  gravity 
of  1.145.  It  is  pitch-black,  slightly  soluble  in  alcohol,  partly  so  in  ether, 
petrolaum,  and  benzole,  but  almost  completely  in  turpentine.  Carbon  di- 
sulphide and  chloroform  dissolve  it  completely. 

Grahamite  was  originally  found  in  the  Carboniferous  sandstones  of 
Ritchie  County,  W.  Va.  There  it  occurred  in  a  deep  vertical  fissure  1  to  5 
feet  wide  at  the  surface,  and  nearly  a  mile  in  length,  which  was  opened  up  at 
right  angles  to  the  direction  of  an  anticlinal  fold  (Fig.  47) .  Through  this  the 
oil  escaped  upwards  from  an  oil  pool,  known  to  occur  below,  and  was  oxi- 
dized to  grahamite.  The  vein  has  long  since  been  worked  out. 

Deposits  of  grahamite  are  also  known  in  southeastern  Oklahoma,  where 
the  material  occurs  in  steeply  pitching  veins,  in  sandstones,  and  shales. 
The  wall  rocks,  which  are  of  Ordovician  to  Carboniferous  age,  vary  from 


120 


ECONOMIC  GEOLOGY 


flat  to  highly  folded,  and  the  grahamite  shows  corresponding  fluctuations  in 
composition  which  are  due  no  doubt  to  differences  in  the  degree  of  meta- 


FIG.  47. — Map  showing  relation  of  grahamite  fissure  to  anticlinal  fold,  in  Ritchie 
County,  W.  Va.     (After  White,  Bull.  Geol.  Soc.  Amer.,  X.) 

morphism  which  the' rocks  have  undergone.     The  veins  are  uncertain  in 
extent,  and  with  two  exceptions  have  not  warranted  extensive  development. 
Other  deposits  are  located  in  western  Arkansas  but  the  material  is 
badly  crushed  and  more  highly  metamorphosed  (105). 

PROXIMATE  ANALYSES  OF  OKLAHOMA  AND  ARKANSAS  BITUMEN 


I 

II 

III 

Moisture     

.25 

09 

2  51 

Volatile  bitumen 

43  33 

23  06 

17  78 

Fixed  Carbon       ... 

5597 

75  90 

7Q  l£ 

Ash    

1  45 

95 

^fi 

Sulphur 

1  47 

1   fiQ 

1    QC 

I.  Impson  Valley  grahamite.  II.  Black  Fork  Mountain  vein  bitumen. 
III.  Fourche  Mountain  vein  bitumen.  Nos.  II  and  III  occur  in  the  more 
highly  folded  rocks,  and  show  effects  of  metamorphism. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  121 


Wurtzilite  (97)  is  a  bitumen  related  possibly  to  gilsonite,  but  distinguished 
from  it  by  its  behavior  towards  solvents,  and  by  its  elastic  and  sectile 
properties.  It  has  a  hardness  of  2-3,  and  specific  gravity  of  1.03;  is  black, 
with  pitchy  luster,  and  petroleum-like  odor.  Tabbyite  is  regarded  by  some 
as  similar.  Wurtzilite  is  found  filling  fissures  in  Tertiary  calcareous  shales 

and  limestones  in  the  western  part 
of  the  Uinta  Basin,  Utah.  It  has 
been  but  little  mined. 

Lake  Asphalt  (103)  is  not  found 
in  the  tlnited  States,  but  occurs  in 
the  famous  pitch  lake  on  the  island 
of  Trinidad,  off  the  coast  of  Vene- 
zuela. 

The  deposit  PL  XIV,  and  PL  XV, 
Fig.  1,  appears  to  occupy  a  basin- 
shaped  depression  of  about  100 
acres  and  nearly  circular  outline 
(Fig.  48)  lying  138  feet  above  the 
sea  level.  The  material  evidently 
arises  from  some  source  below,  as 
excavations  made  in  the  pitch  fill 
up  again  in  a  short  time.  Two 
forms  of  the  asphalt  are  recognized, 
viz.,  the  lake  pitch  and  the  land 
pitch,  the  latter  being  asphalt  which 
has  overflowed  from  the  lake  at  a 
low  point  on  its  rim,  and  run  down 
to  the  sea.  Up  to  the  present  time 
over  3  million  short  tons  of  asphalt 
have  been  exported  from  the  is- 
land. 


lake. 


FIG.  48.  —  Plan  of  Trinidad  pitch 
(After  Peckham.) 

Manjak  (100  a)  is  the  name  applied  to  a  bitumen 
resembling  Uintaite,  found  on  the  island  of  Barbados. 
'  It  is  a  hydrocarbon  of  high  purity,  black  color,  brilliant 
luster,  and  conchoidal  fracture. 

The  Manjak  is  found  in  veins  cutting  obliquely 
across  the  upper  strata  of  the  oil  series  (Oligocene) 
and  disseminated  through  the  clays.  The  largest 
vein  is  over  27  feet  thick  and  often  shows  unusually 
rich  pockets.  The  close  association  of  this  asphalt 
with  the  petroleum  has  led  most  geologists  to  assume 
its  derivation  from  the  latter. 

Uintaite,    or   Gilsonite    (97),  is  a  black,   brilliant 
bitumen,  with  conchoidal  fracture,  hardness  2  to  2.5, 
and  specific  gravity  of   1.065  to   1.07.     It  is  partly   FIG.   49.  — Section  of 
soluble  in  alcohol  (45.4  per  cent),  more  so  in  ether,  and      Gilsonite  vein,  Utah, 
completely  in  chloroform  and  warm  oil  of  turpentine. 
It  is  found  filling  a  series  of  fissures  (Figs.   49  and 
50),  termed  veins,  in  the  Bridger  beds  of  the  Tertiary 
of  Uintah  and  Wasatch  counties,  northeastern  Utah,  and,  to  a  less  extent,  in 


(After  Eldridge,  U.  S. 
Geol.  Surv.,  17th  Ann. 
Rept.,  /). 


122 


ECONOMIC  GEOLOGY 


western  Colorado.    Ths  veins  strike   usually  northeast-southwest,    and  vary 
greatly  in  width,  extremes  of  18  feet  being 
reported.     They  are  traceable  for  long  dis- 
tances, but  their  vertical  depth  appears  to 
be  unknown. 

Maltha.  —  This  is  usually  found  issuing 
from  crevices  or  pores  of  the  rocks,  the  latter 
being  sometimes  of  bituminous  character. 
It  can  also  be  extracted  from  bituminous 
rock  and  asphaltic  oils. 

Maltha  is  not  known  to  occur  in  large 
deposits  in  the  United  States,  although  it  is 
somewhat  widely  distributed  in  some  of  the 
California  oil  fields,  where  the  petroleum 
exudes  from  the  rocks,  and  on  exposure  to 
the  air  becomes  converted  into  maltha  by 
the  loss  of  its  more  volatile  constituents. 
In  the  Santa  Barbara  (18)  and  Kern  County 
oil  fields  it  is  found  in  fissures  of  limited 
extent.  Its  occurrence  has  also  been  noted 
in  Oklahoma. 

Oil  asphalt  is  obtained  from  the  distillation 
of  certain  asphaltic  oils  of  California  and 
Texas,  and  some  of  these  are  said  to  contain 
over  35  per  cent  of  it.1 


FIG.  50.  —  Gilsonite  mine  at 
Dragon,  Utah.  The  cut 
represents  position  of  vein. 
(Rept.  of  Coal  Mine  In- 
spector, Utah,  1905-1906.) 


ELEMENTARY  ANALYSES  OF  BITUMENS  AND  MALTHA 


1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

1 

i 

HA, 
NTERIA, 

i: 

E 

| 

M      ^ 

rf 

a 

j 

1 

|a 

W« 

H  £ 

d^"1 

WL> 

B;> 

a  •< 

M     •< 

§« 

O  jj 

M  M 

H  5 

J<! 

<£   Q 

m  > 

W     ^ 

•^ 

°e  3 

5  g 

S. 

Sou 

o£ 

o£ 

l| 

S  o 

M  H 

OP 

d  H 
OP 

II 

II 

c  .   . 

85.25 

85.72 

86.57 

76.45 

59.20 

86.04 

85.53 

88.30 

89.28 

80.00 

83.68 

H  .     . 

15.09 

11.83 

7.26 

7.83 

5.77 

8.96 

13.20 

9.96 

8.66 

12.23 

10.84 

N  .     . 

— 

1.21 

1.48 

tr 

1.01 

2.93 

.42 

> 

.79 

1.78 

.45 

O  .     . 

— 

— 

2.00 

13.46 

14.68 

1.97 

r    .32 

S    .     . 

— 

1.32 

1.38 

tr 

— 

tr 

1.20 

1.32 

1.79 

5.83 

5.10 

Ash     . 

— 

— 

1.31 

.10 

19.34 

.10 

— 

.10 

— 

— 

— 

ture 

1,  9,  10,  11.  Richardson,  "Nature  and  Origin  of  Asphalt,"  1898.  2.  Munic.  Eng.  Mag. 
June-August,  1897.  3.  Amer.  Jour.  Sci.,  Sept.  1899,  p.  221.  4.  Wurtz,  analyst,  Amer.  Jour. 
Sci.,  iii,  VI:  415,  1873.  5.  Kite,  analyst,  Geol.  Soc.  Amer.,  Bull.  X:  283,  1899.  A  proximate 
analysis  made  on  another  sample  gave  1.13  sulphur.  6.  Trans.  Amer.  Philos.  Soc.,  Phila.:  853, 
1852.  7.  Richardson,  Modern  Asphalt  Pavement:  209,  1905.  8.  Jour.  Frankl.  Last.,  CXL, 
No.  837,  Sept.  1895. 

1  Taff,  U.  S.  Geol.  Surv.,  Min.  Res.,  1908. 


PLATE  XV 


FIG.   1.  —  View  of  portion  of  Trinidad  asphalt  lake,  showing  digging  operations. 
(Photo,  loaned  by  Barber  Asphalt  Company.) 


FIG.   2.  —  Quarry    of    bituminous  sandstone,   Santa  Cruz,   Cal.     (After   Eldridge, 
U.  S.  Geol  Surv.,  22d  Ann.  Rept.,  /.) 

(123) 


124 


ECONOMIC  GEOLOGY 


BITUMINOUS  ROCKS 

Under  this  heading  are  included  consolidated  and  unconsolidated 
rocks,  whose  pores  are  more  or  less  completely  filled  with  bituminous 
matter,  often  of  asphaltic  character  (97). 

They  are  commonly  classified  according  to  the  character  of  the 
containing  rock  as  bituminous  sands  or  sandstones,  bituminous 
limestones,  shales,  or  schists. 

Bituminous  rocks  vary  not  only  in  their  richness,  but  also  in  their 
value  for  paving  purposes,  for  while  in  some  the  bituminous  matter 
is  purely  asphalt  proper,  in  others  it  may  consist  wholly  or  in  part  of 
maltha  or  some  liquid  bitumen,  which  may  interfere  with  its  use  for 
paving  purposes. 

Deposits  of  bituminous  rock  are  more  widely  distributed  than  the 
vein  bitumens,  being  found  in  several  geological  horizons,  and  are 
worked  in  Kentucky  (97a) ,  Oklahoma  (97a) ,  and  California  (97) . 

In  California  deposits  of  asphaltic  shale  and  sandstone  are  not  of 
rare  occurrence  in  the  oil  regions  from  Santa  Cruz  southward.  The 
bituminous  sandstone  quarried  near  the  above  named  place  (Pl.XV, 
Fig.  2)  is  of  blackish  or  brownish-black  color,  weathering  to  gray, 
and  occurs  beneath  the  Monterey  shales;  it  sometimes  rests  directly 
on  the  granites.     The  bitumen  impregnates  the  heavy-bedded  sand- 
stone immediately  under  the  shale,  and  also  the  sand  that  fills 
cracks  which  extend  up  into  the  shale.     These  cracks,  which  vary 
in  width  from  very  minute  size  up  to  25  or  30  feet,  are  sometimes 
traceable  for  several  hundred  feet,  being  at  times  of  value  as  guides 
in  finding  the  main  bed. 

ANALYSES  OF  BITUMINOUS  ROCKS 


LOCALITY 

MOISTURE 

SOLUBLE 

IN  CS2 

CaCO3 

MgC03 

SAND  OB 
CLAY 

California    . 

2  50 

20  20 

3  00 

7400 

Kentucky    .... 

5  76 

9422 

Seyssel,  France     .     .     . 



8.15 

91.70 



Limmer,  Germany    .     . 

— 

18.26 

56.50 

27.01 

4.98 

The  Kentucky  rock  asphalt  is  found  principally  along  the 
southern  and  eastern  outcrop  of  the  western  Kentucky  coalfield, 
where  it  occurs  in  the  Chester  sandstone,  and  the  lower  sand- 
stones of  the  Coal  Measures.  The  beds  are  3  to  30  feet  thick, 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  125 

with  a  bituminous  content  ranging  from  5  to  21  per  cent,  but  7 
per  cent  is  claimed  to  be  sufficient  for  commercial  purposes  (96a) . 

In  Oklahoma  deposits  have  been  found  in  a  belt  extending 
from  the  Arkansas  boundary  westward  to  the  Wichita  Moun- 
tains. The  material  includes  bituminous  sandstone  of  Permian 
and  also  Pennsylvanian  age,  and  Ordovician  limestones  (lOOa). 

Large  quantities  of  bituminous  rock  are  obtained  from  the 
Jurassic  limestones  of  France,  from  Tertiary  limestones  of  Italy, 
as  well  as  other  localities  in  Europe.1 


OIL  SHALES 

Shale  containing  sufficient  petroleum  to  permit  its  extraction 
by  a  process  of  distillation  is  known  as  torbanite  or  kerosene 
shale  (80-84).  Such  shales  are  found  in  the  Carboniferous  of 
New  South  Wales,  Australia,  New  Zealand,  and  Scotland,  and 
in  the  Cretaceous  of  Brazil.  Those  in  New  South  Wales  have 
been  worked,  and  in  Scotland  the  industry  has  thrived  under 
careful  management  for  a  number  of  years  (83) . 

In  the  last  named  country  the  crude  oil  extracted  by  distilla- 
tion from  a  ton  of  shale  varies  from  16  to  35  gallons,  while  the 
ammonium  sulphate  ranges  from  30  to  75  pounds. 

Highly  bituminous  shale  is  known  to  occur  in  the  Green 
River  (Tertiary)  formation  of  the  Uinta  Basin  in  Colorado  and 
Utah  (84a).  It  forms  lenticular  beds  from  one-half  inch  to  80 
feet  in  thickness,  is  light  to  dark  brown  in  color,  and  gives  a 
petroleum  odor  when  struck  with  the  hammer.  The  shale  turns 
gray  on  prolonged  weathering. 

The  amount  of  oil  obtained  varied  from  10.4  to  61.2  gallons, 
with  an  average  of  30.4  gallons.  Much  of  the  bituminous  material 
is  in  the  form  of  liquid  oil,  semisolid  and  solid  asphalt.  The 
oil  distilled  in  the  field  had  a  gravity  of  26.5  to  16.0  Beaume*. 
The  occurrence  of  a  considerable  proportion  of  unsaturated 
carbons  in  these  as  well  as  the  Scotch  shales,  may  involve  some 
loss  in  refining. 

In  Albert  and  Westmoreland  counties  of  New  Brunswick, 
Canada,  there  is  a  considerable  area  underlain  by  black,  brown, 
and  gray  shales  of  Subcarboniferous  age,  which  contain  a  num- 
ber of  bands  of  oil  shale.  Tests  of  some  of  these  have  yielded 

iDammer  and  Tietze,  Die  Nutzbaren  Mineralien,  II:  493,  1914. 


126 


ECONOMIC   GEOLOGY 


63  gallons  of  crude  oil  per  ton,  and  in  1909  investigations  were 
under  way  looking  towards  their  development  (84) . 
The  following  analysis  indicates  the  composition  of  an  oil  shale : 


. 

MOIS- 
TURE 

VOLATILE 
HYDRO- 

CAHBON 

FIXED 
CARBON 

ASH 

SULPHUR 

Rich  shale,  Joadja,  N.S.W.    . 

.16 

89.59 

5.27 

4.96 

.384 

The  oil  can  be  obtained  by  distillation  in  retorts ;  but  in  view  of  the  large 
available  supplies  of  petroleum,  obtainable  in  many  parts  of  the  world, 
the  material  at  present  has  but  little  commercial  value. 

Origin  of  Solid  Bitumens  and  Bituminous  Rocks.  —  A  study 
of  the  deposits  leads  to  the  conclusion  that  these  solid  bituminous 
compounds  have  been  derived  from  petroleum  (87, 88, 89, 90),  for  the 
following  reasons :  In  the  vein  deposits  the  solid  bitumens  are  often 
associated  with  petroleum  springs,  or  with  fissures  leading  down  to  or 
toward  petroleum-bearing  strata.  In  some  cases  the  material  not 
only  fills  such  a  fissure,  but  impregnates  the  wall  rock  to  a  distance 
of  a  foot  or  more  on  either  side  of  the  vein,  indicating  that  the 
material  came  up  through  the  fissure  in  a  liquid  condition,  filling  it, 
and  even  penetrating  the  wall  rock. 

The  bitumen  in  bituminous  rocks  may  either  have  originated  from 
organic  remains  within  the  rock  itself  or  have  seeped  into  it  from 
some  neighboring  pool.  In  either  case  the  material  seems  originally 
to  have  been  liquid  petroleum,  some  of  which  later  solidified. 

Uses  of  Asphalt.  • —  Trinidad  asphalt  mixed  with  powdered 
rock  and  tar  is  much  in  use  for  pavements,  and  the  bituminous 
rocks  are  employed  for  similar  purposes.  Ozokerite,  known  as 
Ceresin  in  its  purified  form,  is  Used  in  the  manufacture  of  candles, 
ointments,  powders,  as  an  adulterant  of  beeswax,  and  for  bottles 
to  hold  hydrofluoric  acid.  Ichthyol  is  obtained  from  an  Austrian 
bituminous  rock  filled  with  fossil  fish. 

Uintaite  and  Manjak  are  used  for  making  low-grade  and 
dipping  varnishes,  for  iron  work  and  baking  Japans.  Other 
uses  of  Uintaite  are  for  preventing  electrolytic  action  on  iron 
plates  of  ship  bottoms,  coating  masonry,  acid-proof  lining  for 
chemical  tanks,  roofing  pitch,  insulating  electric  wires,  as  a  sub- 
stitute for  rubber  in  common  garden  hose,  and  as  a  binder 
pitch  in  making  coal  briquettes. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  127 

Production  of  Petroleum  and  Natural   Gas.  —  Petroleum  has 
long   been  known  in  many  parts   of  the  world   because  of  its 


1  Appalach  an  Field  ) 


2  Indiana-Ohio  FJieldf  f^"1"  "l 

3  Illinois  Field.  Ijroduction  less  than  200.COO  Barrels  before  19C5. 

4  Mid-continental  Field.  Production  very  small  prior  t 

5  Gulf  FielJd.  Production  very  slight  prior  to  1898 


o   ^  c*  « 

2  2SSJ 


FIG.  51. 


presence  in  bituminous  springs  or  as  a  floating  scum  on  the  sur- 
face of  pools.  It  was  used  at  an  early  date  on  the  walls  of  Baby- 
lon and  Nineveh,  and  was  obtained  by  the  Romans  from  Sicily 
for  use  in  their  lamps. 


128 


ECONOMIC  GEOLOGY 


In  the  United  States  petroleum  was  mentioned  by  French  mis- 
sionaries even  in  1635,  and  the  early  Pennsylvania  settlers  obtained 
small  quantities  by  scooping  out  the  oil  from  dug  wells.  Its  dis- 
covery at  a  greater  depth  on  the  western  slope  of  the  Alleghanies 
was  made  during  the  drilling  of  brine  wells;  but  its  early  use  was 
chiefly  a  medicinal  one  until  1863,  when  attempts  were  made  to 
purify  it  for  use  as  a  lubricant  and  illuminant.  The  beginning  of 
the  oil  industry  is  usually  considered  to  date  from  the  sinking  of  a 
successful  well  by  Colonel  Drake  on  Oil  Creek,  Pennsylvania,  in 
1860.  From  this  center  prospectors  spread  out  in  all  directions, 
making  valuable  discoveries,  until  now  petroleum  production  and 
refining  rank  among  the  leading  industries  of  the  country,  the  supply 
coming  from  many  states. 

Natural  gas  was  discovered  and  first  employed  for  economic  pur- 
poses at  Fredonia,  New  York,  in  1821.  In  1841  it  was  used  in  the 
Great  Kanawha  Valley  as  a  fuel  in  salt  furnaces,  but  its  first  ex- 
tensive use  began  in  1872  at  Fairview,  Pennsylvania.  It  was  used 
in  1885  for  iron  smelting  at  Etna  Borough  near  Pittsburg,  and  in 
1886  was  piped  nineteen  miles  from  Murray sville  to  Pittsburg. 
Now  natural  gas  is  piped  long  distances  to  cities,  being  used  as  a 
fuel  in  many  industries,  as  well  as  for  domestic  heating  and  lighting. 

The  following  tables  give  the  production  of  oil  and  gas  from  1909 
to  1914  inclusive.  The  production  of  oil  since  1884  is  shown  dia- 
grammatically  in  Fig.  51.  Where  the  production  has  fallen  below 
200,000  barrels  no  attempt  has  been  made  to  show  it.  This  affects 
only  the  Gulf  and  Mid-Continental  fields. 

QUANTITY  AND  VALUE  OF  PETROLEUM  MARKETED  IN  UNITED  STATES, 

1909-1911 


19 

09 

19 

10 

19 

LI 

Quantity, 
bbl. 

Value. 

Quantity, 
bbl. 

Value. 

Quantity, 
bbl. 

Value. 

California 

55,471,601 

$30,756,713 

73,010,560 

$35.749.473 

81.134,391 

$38.719.080 

Colorado  . 

310,861 

318,162 

239,794 

243.402 

226,926 

228.104 

Illinois 

30,898,339 

19,788,864 

33,143,362 

19,669,383 

31,317,038 

19,734.339 

Indiana     . 

2,296,086 

1.997,610 

2,159,725 

1.568.475 

1.695,289 

1.22S.835 

Kansas 

1,263,764 

491,633 

1.128,668 

444,763 

1,27«.819 

608.756 

Kentucky 

639,016 

518,299 

468.774 

324,684 

472,458 

328,614 

Louisiana 

3,059,531 

2.022,449 

6.841,395 

3,574.069 

10.720,420 

5,668.814 

New  York 

1,134,897 

1,878,217 

1.053.838 

1.414.668 

952.515 

1.248.950 

Ohio     .     . 

10,632,793 

13,225,377 

9,916.370 

10.651.568 

8.817.112 

9,479.542 

Oklahoma 

47.859,218 

17,428,990 

52.028.718 

19,922.660 

56,069.637 

26.451,767 

Pennsylvania 

9,299,403 

15,424.554 

8.794.662 

11.908.914 

8.248.158 

10,894.074 

Texas   .     .     . 

9,534,467 

6.793,050 

8.899.266 

6.605,755 

9.526.474 

6,554.552 

West  Virginia 

10,745,092 

17.642.283 

11.753,071 

15.723.544 

9.795,464 

12.767.293 

Wyoming  !     . 

20,056 

34,456 

115,430 

93,536 

186,695 

124.037 

Other  States 

5,750 

7.830 

3.615 

4,794 

7.995 

7.995 

United  States     . 

183,170,874 

$128.328.487 

209.557.248 

$127.899,688 

220,449,391 

$134.044.752 

1  Includes  Utah. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  129 


QUANTITY  AND  VALUE  OF  PETROLEUM  MARKETED  IN  UNITED  STATES, 
1909-1914— Continued 


19 

12 

19 

13 

19 

14 

Quantity, 
bbl. 

Value. 

Quantity, 
bbl. 

Value. 

Quantity, 
bbl. 

Value. 

California 

1  87,272,593 

$139,624,501 

97,788.525 

$45,709,400 

99.775,327 

$48,066,096 

Colorado  . 

206,052 

199,661 

188,799 

174,779 

222,773 

200,894 

Illinois 

23,601,308 

24,332.605 

23,893,899 

30,971,910 

21,919,749 

25,426,179 

Indiana     .     .     . 

970,009 

885,975 

956,095 

1,279,226 

1,335,456 

1,548,042 

Kansas 

1,592,796 

1,095,698 

2,375,029 

2,248,283 

3,103,585 

2,433,074 

Kentucky 

484,368 

424,842 

524.568 

675,748 

502,441 

498,556 

Louisiana 

9,263,439 

7,023,827 

12,498,828 

12,255,931 

14,309,435 

12,886,897 

New  York 

874,128 

1,401,880 

948,191 

2,284,307 

933,974 

1,760,868 

Ohio      .... 

2  8,969,007 

2  12,085,998 

8,781,468 

17,538,452 

8,536,352 

13,372,729 

Oklahoma 

51,427,071 

34,672,604 

63,579,384 

59,581,948 

73,631,724 

57,253,187 

Pennsylvania 

7,837,948 

12,886,752 

7,917,302 

19,690,502 

8,170,335 

15,573,822 

Texas    .... 

11,735,057 

8,852,713 

15,009,478 

14,675,593 

20,068,184 

14,942.848 

West  Virginia     . 

12,128,962 

19,927,721 

11,567,299 

28,828,814 

9,680,033 

18,468.540 

Wyoming 

1,572,306 

798,470 

2,406,522 

1,187,232 

3,560,375 

1,679,192 

Other  States 

10,843 

19,263 

7,792 

14,291 

United  States     . 

222.935,044 

S164.213.247 

248,446,230 

$237,121,388 

265,762.535 

$214,125,215 

1  Includes  Alaska. 


2  Includes  Michigan. 


The  average  price  per  barrel  of  petroleum  naturally  varies 
somewhat  from  year  to  year.  In  1885  it  was  87Jj£;  in  1890, 
86f&  in  1900,  $1.194;  in  1903,  94^;  in  1908,  73.1^;  in  1908, 
72.2^  in  1912,  73.7^;  in  1913,  95.4^f;  in  1914,  80.6£ 

The  total  number  of  barrels  of  petroleum  produced  in  the 
United  States  from  1859  to  the  end  of  1914  was  3,335,457,140,  with 
a  value  of  $2,789,829,745,  while  the  total  value  of  natural  gas 
produced  in  the  United  States  from  1882  to  the  end  of  1908  was 
approximately  $1,060,590,712. 

MARKETED  PRODUCTION  OF  PETROLEUM  IN  THE  UNITED  STATES, 
1910-1914,  BY  FIELDS,  IN  BARRELS. 


Field. 

1910 

1911 

1912 

1913 

1914 

Appalachian  
Lima-Indiana  

26,892,579 
7,253.861 
33  143  362 

23,749,832 
6,231,164 
31  317,038 

26,338,516 
1  4,925,906 
28  601  308 

25,921,785 
4.773,138 
23  893,899 

24,101,048 
5,062,543 
21  913  749 

Mid-Continent  
Gulf    

59,217,582 
9,680,465 

66,595,477 
10,999,873 

65,473,345 
8,545,018 

84,920,225 
8,542,494 

97,995,400 
13,117,528 

California 

73  010,560 

81,134,391 

287,272,593 

97,788,525 

99,775  327 

Colorado  and  Wyoming 
Other  fields 

s  358,839 

3421,616 

1,778,358 

2,595,321 
4  10  843 

3,783,148 
5  7  792 

Total 

209,557,248 

220,449,391 

222,935,044 

248,446,230 

265,762,535 

1  Includes  Michigan. 

2  Includes  Alaska. 

5  Includes  Alaska,  Michigan,  and  Missouri. 


3  Includes  Michigan  and  Missouri. 

4  Includes  Alaska,  Michigan,  Missouri,  and  New  Mexico. 


The  world's  production  of  petroleum  from  1911  to  1914  was  as 
follows : — 


130 


ECONOMIC   GEOLOGY 


WORLD'S  PRODUCTION  OF  CRUDE  PETROLEUM,  1911-1914,  BY 

COUNTRIES 
(Barrels  of  42  gallons) 


1913 

1914 

Percent- 
age of 

COUNTKY. 

1911 

1912 

Total 
Produc- 

Barrels. 

Metric 
tons. 

Barrels. 

Metric 
tons. 

tion. 
1914 

United  States     . 

220,449,391 

222,113,218 

248,446,230 

33,126,164 

265,762,535 

35,435,005 

66.36 

Russia 

66,183,691 

68,019,208 

60,935,482 

8,124,731 

67,020,522 

8,936,070 

16.74 

Mexico 

14,051,643 

16,558,215 

25,696,291 

3,426,172 

21,188,427 

2,825,124 

5.29 

Roumania 

11,107,450 

12,991,913 

13,554.768 

1,885,225 

12,826,579 

1,783,947 

3.20 

Dutch  East  Indies 

12,172,949 

10,845,624 

11,966,857 

1,534,223 

12,705,208 

1,634,403 

3.17 

Galicia 

10,519,270 

8,535,174 

7,818,130 

1,087,286 

5,033,350 

i  700,000 

1.26 

India    . 

6,451,203 

7,116,672 

i  7,500,000 

1,000,000 

i  8,000,000 

1,066,667 

2.00 

Japan  . 

1,658,903 

1,671,405 

1,942,009 

258,934 

2,738,378 

365,117 

.68 

Peru     .     . 

1,368.274 

1,751,143 

1,857,355 

247,647 

1,917,802 

255,707 

.48 

Germany 

1,017,045 

995,764 

i  995,764 

132,769 

995,764 

1  140,000 

.25 

Egypt  .     . 



__, 



.     

777,038 

103,605 

.19 

AJ&J'H~    • 

Canada      . 

291,096 

243,614 

228,080 

30.410 

214,805 

28,641 

.05 

Trinidad   . 



r 



L 

643,533 

85,804 

.16 

Italy     .     . 

74,709 

1  86,286 

i  50,334 

7,000 

39,548 

i  5,500 

.01 

Other    .... 

1200,000 

250,000 

517,616 

69,015 

~—  — 





Total    .... 

345,512,185 

351,178,236 

381,508.916 

50,929,576 

400,483,489 

53,448,257 

1  Estimated. 

APPROXIMATE  VALUE  OF  NATURAL  GAS  PRODUCED  IN  THE  UNITED  STATES, 

1909-1914 


STATE 

1909 

1910 

1911 

1912 

1913 

1914 

Pennsylvania 

$20,475,207 

$21,057,211 

$18,520,796 

$18,539,672 

$21,695,845 

$20,401,295 

New  York 

1,222,666 

1,678,720 

1,418,767 

2,343,379 

2,425,633 

2,600,000 

Ohio      .... 

9,966,938 

8,626,954 

9,367,347 

11,891,299 

10,416,699 

14,667,790 

West  Virginia     . 

17,538,565 

23,816,553 

28,435,907 

33,324,475 

34,164,850 

35,515,329 

Illinois 

644,401 

613,642 

687,726 

616,467 

574,015 

437,275 

Indiana 

1  616  903 

1  473  403 

1,192,418 

1  014  295 

948,278 

755  407 

Kansas 

8,293,846 

7,755,367 

4,854,534 

4,336,635 

3,288,394 

3.340,025 

Missouri    . 

10,025 

12,611 

10,496 

11,576 

6,795 

5,319 

California       .     . 

446,933 

476,697 

800,714 

1,134,456 

1,883,450 

2,910,784 

Texas    .... 

) 

1,014,945 

1,405.077 

2,073,823 

2,469,770 

Alabama  .     .     . 
Louisiana 

[      453,253 

956,683 

}      858,145 

1,747.379 

2,119,948 

2,227.999 

Kentucky       .     . 

485.192 

456,293 

407,689 

522,455 

509,846 

490.875 

Tennessee 

350 

300 

300 

375 

600 

300 

Arkansas  and 

Wyoming  . 

226,925 

301,151 

295,858 

309,816 

269.421 

1214,103 

Oklahoma 

1,806,193 

3,490,704 

6,731,770 

7.334,599 

7,436,389 

8.050.039 

South  Dakota    . 
North  Dakota    . 

16,164 
3,025 

31,999 
[    7,010 

16,984 
5.738 

}       30.412 

31,166 

27.220 

Oregon 

50 

Iowa     .... 

50 

40 

70 

120 

120 

200 

Michigan       .     . 

255 

820 

1,330 

1,470 

1,405 

1.442 

Total     .     .     . 

$63,206,941 

$70.756,158 

$74.621,534 

$84,563,957 

$87,846,677 

$94,115,524 

1  Includes  Colorado. 

No  imports  or  exports  of  natural  gas  have  been  reported  during 
the  period  1909-1913. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  131 
EXPORTS  OF  MINERAL  OILS  FROM  UNITED  STATES,  1911-1914 


Kind. 

1911 

1912 

1913 

1914 

Crude 

$6  165  403 

$6  770  484 

$8  448  294 

$4  958  838 

Naphtha     

11,482,761 
61  055  095 

20,459,378 
62  084  022 

28,091,608 
72  042  107 

25,288,414 
64  112  77^ 

Lubricating  and  Paraffin   . 
Residuum  

23,337,126 
3,882,463 

28,297,467 
6,599,031 

29,608,549 
11,125,851 

26,316,313 
19,224,250 

Total 

$105  922  848 

$124  210  382 

$149  316  409 

$139  900  587 

PRODUCTION  OF  PETROLEUM  IN  ONTARIO  AND  NEW  BRUNSWICK,  1911-1914 


Year. 

Barrels. 

Value. 

Ontario. 

New  Brunswick. 

Canada. 

1911                            .  "  . 

288,635 
240,935 
226,166 
212,495 

2.461 
2,679 
2,111 
1,725 

$357,073 
345,050 
406,439 
343,124 

1912          

1913 

1914     ...... 

VALUE  OF  NATURAL  GAS  PRODUCED  IN  CANADA  BY  PROVINCES,  1911-1914 


Year. 

New  Brunswick. 

Alberta. 

Ontario. 

Total. 

1911     .... 
1912     .... 
1913     .... 
1914     .      .      .      . 

$     110,165 
289,906 
1,079,466 
1,250,320 

$1.807,513 
2,036,245 
2,055,768 
2,346,687 

$1,917,678 
2,362,700 
3,309,381 
3,651,256 

$  36,549 
174,147 
54,249 

Production  of  Asphalt  and  Bituminous  Rock. — The  production 
of  these  two  substances  by  kinds  and  by  states  as  well  as  the 
imports  and  exports  are  given  below. 

MARKETED  PRODUCTION  OF  ASPHALT,   1910-1914,  BY  VARIETIES, 
IN  SHORT  TONS 


Variety. 

1910 

1911 

Quantity. 

Value. 

Quantity. 

Value. 

Bituminous  Rock     . 
Maltha              

64,554 
1,252 

2  33,087 
161,187 

$    400,557 
12,742 

i  42,654 
8,574 
610 
30,236 
5,000 

277,192 

$  i  159,670 
125,966 
30,500 
486,114 
15,000 

3,173,859 

Wurtzilite  (elaterite)     .      . 
Gilsonite     
Grahamite       
Ozokerite  and  Tabbyite    . 
Oil  asphalt  or  manufactured 

Total              .... 

2  440,935 

2,225,833 

260,080 

$3,080,067 

364,266 

$3,991,109 

1  Includes  small  output  of  mastic. 

2  Includes  gum. 


132 


ECONOMIC  GEOLOGY 


MARKETED  PRODUCTION  OF  ASPHALT,   1910-1914,   BY  VARIETIES, 
IN  SHORT  TONS — Continued 


1 

912 

] 

913 

] 

914 

Variety 

Quan- 
tity. 

Value. 

Quan- 
tity. 

Value. 

Quan- 
tity. 

Value. 

Bituminous  Rock    . 
Maltha       

1  54,762 
474 

$  i  173,018 
3,518 

57,549 

$173,764 

48,771 

$  151,122 

Wurtzilite  (elaterite)    . 
Gilsonite    
Grahamite      .... 
Manufactured  or  oil 
asphalt  

8,452 
31,478 
(2) 

354,344 

115,620 
573,069 

(2) 

3,755,506 

35,055 
436,586 

576,949 
4,531,657 

/  19,  148 
\    9,669 

360,683 

405,966 
73,535 

3,016,969 

Total       .... 

449,510 

$4,620,731 

529,190 

$5,282,370 

438,271 

$3,647,692 

1  Includes  small  output  of  mastic. 

2  Included  under  wurtzilite. 


Since  deposits  of  the  purer  type,  such  as  lake  asphalt,  are  ve:  y 
scarce  in  the  United  States,  the  supply  for  domestic  consumption 
is  obtained  from  foreign  countries.  The  imports  for  the  last  five 
years  are  given  below: — 


ASPHALT  IMPORTED  FOR  CONSUMPTION  INTO  THE  UNITED  STATES,  1910-1914, 

IN  SHORT  TONS 


YEAR. 

CRUDE. 

DRIED  OR 
ADVANCED. 

BITUMINOUS 
LIMESTONE. 

TOTAL. 

Quan- 
tity. 

Vaiue. 

Quan- 
tity. 

Value. 

Quan- 
tity. 

Value. 

Quan- 
tity. 

Value. 

1910     .     . 
1911     .     . 
1912     .     . 
1913     .     . 
1914     .     . 

162,435 
167,681 
193,645 
2207,033 
137,352 

$588,206 
572,198 
726,345 
738,452 
664,558 

20,180 
20,461 
20,707 
*  14,750 

$178,704 
184,954 
177,992 
133,336 

3,696 
8,180 
3,976 
6,395 
1,705 

$  9,301 
23,468 
15,808 
38,823 
11,060 

186,311 
196,322 
218,328 
228,178 
139,057 

$1785.963 
789,236 
921,145 
910,611 
675,618 

1  Imports  for  1909  include  $8,988  of  manufactures;    1910,  $9,752. 

2  Includes  dried  or  advanced  asphalt  for  last  three  months  of  1913. 

3  Last  three  months  of  1913  included  in  crude  asphalt. 

Most  of  the  asphalt  mported  from  foreign  countries  comes  from 
the  island  of  Trinidad,  but  other  important  sources  are  Venezuela 
(Bermudez),  Cuba,  Germany,  Italy,  and  Mexico.  Small  amounts 
are  also  brought  from  Switzerland,  France,  the  United  Kingdom. 
Turkey  in  Asia,  Colombia,  and  Netherlands. 

The  ozokerite  imported  for  consumption  in  1913  amounted 
to  7,141,514  pounds,  valued  at  $ 549,992;  in  1914  the  quantity 
imported  rose  to  8,191,529  pounds  valued  at  $498,655. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  133 

The  imports  of  ichthyol  jn  1914  amounted  to  61,416  pounds, 
va'.ued  at  $56,415. 

During  the  fiscal  year  1914,  asphalt  and  manufactured  asphaltic 
material  to  the  value  of  $1,247,020  were  exported  from  the  United 
States  to  other  countries  as  against  similar  exports  valued  at 
$1,679,411  during  1913. 

REFERENCES  ON   PETROLEUM 

ORIGIN,  OCCURRENCE,  AND  TECHNOLOGY.  1.  Becker,  U.  S.  Geol.  Surv.f 
Bull.  401,  1909.  (Relation  magnetic  disturbances  to  petroleum  origin.) 
la.  Bosworth,  Geol.  Mag.  IX:  16  and  53,  1912.  2.  Clapp,  Econ.  Geol., 
IV:  565,  1909.  (Anticlinal  theory.)  2a.  Campbell,  Econ.  Geol.  VI: 
363,  1911.  (Origin  theories.)  26.  Clapp,  Can.  Dept.  Mines,  Mines 
Branch,  No.  291,  1914.  (Technology  and  exploitation.)  2c.  Clapp, 
Econ.  Geol.  V:  503,  1910,  and  VII:  364,  1912.  (Classification.)  Econ. 
Geol.  VI:  1,  1911.  (Oil  and  gas  in  monoclines.)  2d.  Coste,  Amer. 
Inst.  Min.  Engrs.,  Trans.,  XXI:  504,  1914.  (Volcanic  theory.)  Dis- 
cussion of  same  by  Hofer.  2e.  Craig,  Oil  finding,  London,  1914.  2/. 
Gilpin  and  Bransky,  U.  S.  Geol.  Surv.,  Bull.  475,  1911.  (Oil  diffusion 
in  fuller's  earth.)  2g.  Hager,  Practical  Oil  Geology,  New  York,  1915. 
2h.  Harris,  Science,  n.  s.,  XXV:  546,  1912.  (Oil  around  salt  domes.) 
3.  Dalton,  Econ.  Geol.,  IV:  603,  1909.  (Origin.  Excellent.)  3a. 
Coste,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXV:  288,  and  Can.  Min. 
Inst.  Jour.,  XII.  (Volcanic  origin.)  4.  Hofer,  Das  Erdol,  2d  ed.. 
1906.  (Brunswick,  Ger.)  5.  Hofer,  Econ.  Geol.  V:  564, 1910.  (Origin.) 
5a.  Hofer,  Econ.  Geol.  VII:  536,  1912.  (Temperatures  in  oil  regions.) 
5b.  Johnson,  Science,  n.  s.,  XXXV:  458,  1912,  and  Econ.  Geol.,  VI: 
808,  1911.  (Origin  and  accumulation.)  5c.  Johnson,  Amer.  Inst. 
Min.  Engrs.,  Bull.  98,  1915.  5d.  Lucas,  Science,  n.  s.,  XXXV:  961, 
1912.  (Dome  theory.)  6.  Munn,  Econ.  Geol.,  IV:  141  and  509, 
1909.  (Anticlinal  and  hydraulic  theories.)  7.  Newberry,  Ohio  State, 
Agric.  Rept.,  1859.  8.  Orton,  Geol.  Soc.  Amer.,  Bull.  IX:  85,  1892. 
(Origin  and  accumulation.)  9.  Orton,  Kentucky  Geol.  Surv.,  1894. 
(Origin.)  10.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  616,  1916.  11.  Peck- 
ham,  Day,  Mabery,  etc.,  Proc.  Amer.  Phil.  Soc.,  XXXVI:  93.  (Origin 
and  composition.)  12.  Redwood,  B.,  Treatise  on  Petroleum.  (Excel- 
lent.) London.  12a.  Tarr,  Econ.  Geol.  VII:  647,  1912.  (Magnetic 
declination.)  12&.  Thompson,  Petroleum  mining,  New  York,  1910. 
12c.  Washburne,  Amer.  Inst.  Min.  Eng.,  Trans.,  L:  829,  1915.  (Capil- 
lary concentrations.)  13.  White,  Geol.  Soc.  Amer.,  Bull.  Ill:  187, 
1892.  (Anticlinal  theory.) 

AREAL  REPORTS.  Many  analyses  of  oil  have  been  published  in  the 
Mineral  Resources,  U.  S.  Geol.  Survey,  since  1907.  Alaska:  14.  Mar- 
tin, U.  S.  Geol.  Surv.,  Bull.  250,  1905.  Also  U.  S.  Geol.  Surv.,  Bull. 
394:  190,  1909,  and  Brooks,  Amer.  Inst.  Min.  Engrs.,  Trans.,  LI: 
611,  1915.  —  California:  15.  Arnold  and  Garfias,  Amer.  Inst.  Min. 
Engrs.,  Bull.  87,  1914.  15a.  Arnold  and  Johnson,  H.  R.,  U.  S.  Geol. 


134  ECONOMIC   GEOLOGY 

Surv.,  Bull.  406,  1910.  (McKittrick-Sunset  field.)  156.  Fcrstner, 
Econ.  Geol.,  VI:  138,  1911.  (S.  Midway  field.)  16.  Watts,  Bull. 
Calif.  State  Min.  Bureau,  No.  3.  (Central  Valley.)  17.  Eldridge 
and  Arnold,  U.  S.  Geol.  Surv.,  Bull.  309,  1907.  (Santa  Clara  Valley, 
Puente  Hills,  and  Los  Angeles.)  18.  Arnold  and  Anderson,  U.  S. 
Geol.  Surv.,  Bull.  322,  1907.  (Santa  Maria  district.)  19.  Arnold, 
Ibid.,  Bull.  321,  1907.  (Summerland  district.)  20.  Arnold  and  Ander- 
son, Ibid.,  Bull.  398,  1910.  (Coalinga.)  —  Colorado:  21.  Fenneman, 
U.  S.  Geol.  Surv.,  Bull.  260:  436,  1905  (Florence  field,)  and  Washburne, 
Ibid.,  Bull.,  381 D:  45,  1909.  (Florence  field.)  22.  Fenneman,  U. 
S.  Geol.  Surv.,  Bull.  225:  383,  1904.  (Boulder  field.)  —  Illinois:  23, 
Bain,  111.  Geol.  Surv.,  Bull.  8:  273,  1907.  23a.  Blatchley,  111.  Geol.  Surv. 
Bull.  16,  1910.  (111.)  236.  Wheeler,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XL VIII:  533,  1915.  (General.)  Indiana:  24.  Blatchley,  Ind.  Dept. 
Geol.,  22d  Ann.  Kept.:  155,  1898.  (Trenton  limestone  field.)  25. 
Chapters  on  petroleum  in  other  annual  reports  of  this  series.  26.  Orton, 
U.  S.  Geol.  Surv.,  8th  Ann.  Kept.,  II:  475,  1889.  (Trenton  limestone 
—  Kansas:  27.  Adams,  U.  S.  Geol.  Surv.,  Bull.  184,  1901.  28.  Haworth, 
and  others,  Kansas  Geol.  Surv.,  IX,  1908.  (General.)  29.  See  also 
Volumes  on  Mineral  Resources:  issued  by  Kansas  Geol.  Surv.  from 
1897  to  1901.  30.  Schrader  and  Haworth,  U.  S.  Geol.  Surv.,  Bull. 
260:  442,  1905.  (Independence  quadrangle.)  31.  Adams,  Haworth, 
and  Crane,  Ibid.,  Bull.  238,  1904.  (lola  quad.) —Kentucky:  32. 
Munn,  U.  S.  Geol.  Surv.,  Bull.  579,  1914.  (Wayne  and  McCreary 
counties.)  32a.  Ibid.,  471:  9,  1912.  (Campton  pool),  and  p.  18. 
(Knox  county.)  33.  Hoeing,  Ky.  Geol.  Surv.,  Bull.  1,  1904.  —  Louisiana: 
34.  Harris,  U.  S.  Geol.  Surv.,  Bull.  429,  1910.  (General.)  35.  Harris, 
Perrine,  and  Hopper,  La.  Geol.  Surv.,  Bull.  8,  1909.  (Caddo  field.)  — 
Michigan:  36.  Gordon,  Mich.  Geol.  Surv.,  Ann.  Kept,,  1901:  269, 
1902.  (Port  Huron  field.)  —New  York:  37.  Orton,  N.  Y.  State  Mus. 
Bull.  30,  1899.  (General.)  38.  Annual  bulletins  on  mining  industry,  by 
N.  Y.  State  Museum.  —  Ohio:  39.  Bownocker,  Ohio  Geol.  Surv., 
4th  Series,  Bull.  1,  1903.  39a.  Bownocker,  Econ.  Geol.  VI:  37,  1911. 
(Clinton  sand.)  396.  Bownocker,  Ohio  Geol.  Surv.,  4th  ser.,  Bull. 
12,  1910.  (Bremen  field.)  40.  Griswold,  U.  S.  Geol.  Surv.,  Bull.  198. 
(Bereagrit  oil.)  40a.  Hubbard,  Econ.  Geol.,  VIII:  681,  1913.  (Ober- 
iin  district.)  41.  Mabery,  Amer.  Chem.  Jour.;  Dec.,  1895.  (Com- 
position.) 42.  Orton,  Ohio  Geol.  Surv.,  VI:  60.  43.  Orton,  U.  S. 
Geol.  Surv.,  8th' Ann.  Kept.,  II:  475,  1889.  (Trenton  limestone  field.) 
44.  Griswold,  U.  S.  Geol.  Surv.,  Bull.  198,  1902  (Cadiz  quadrangle), 
and  Bull.  346,  1908,  also  Condit,  U.  S.  Geol.  Surv.,  Bull.  541:  9,  1914 
(Flushing  quadrangle.)  —  Oklahoma:  45.  Gould,  Econ.  Geol.,  VII: 
719,  1912.  (General.)  45a.  Hutchinson,  Okla.  Geol.  Surv.,  Bull. 
2:  94,  1911.  (General.)  456.  Buttram,  Okla.  Geol.  Surv.,  Bull.  18, 
1914.  (Gushing  pool.)  45c.  Gould,  Econ.  Geol.,  VIII:  768,  1913, 
(Red  beds.)  45d.  Smith,  U.  S.  Geol.  Surv.,  Bull.  541:  34,  1914. 
(Glen  pool.)  45e.  Taff  and  Shaler,  U.  S.  Geol.  Surv.,  Bull.  260:  441. 
1905.  (Muskogee  field.  —  Oregon:  45/.  Washburne,  U.  S.  Geol. 
Surv.,  Bull.  590,  1914.  (N.  w.  Ore.)  ^-Pennsylvania:  46.  Carll, 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  135 

Ann.  Rept.  Pa.  Geol.  Surv.,  1885;  II,  1886.  47.  Reports  I  to  I  5  of 
the  same  survey.  48.  Report  Pa.  Top.  and  Geol.  Surv.,  1908-1908, 
App.  E:  266,  1908.  (General  and  contains  further  references.)  48a.. 
Shaw  and  Munn,  U.  S.  Geol.  Surv.,  Bull.  454,  1911.  (Foxburg  quad.)  — 
Tennessee:  486.  Ashley,  Res.  Tenn.,  II,  No.  7,  and  Munn.,  Tenn.  Geol. 
Surv.,  Bull.  2,  1911.  — Texas:  49.  Adams,  U.  S.  Geol.  Surv.,  Bull. 
184,  1901.  (General.)  50.  Fenneman,  U.  S.  Geol.  Surv.,  Bull,  282, 
1906.  51.  Phillips,  Tex.  Univ.  Min.  Surv.,  Bull.  No.  1,  1900.  (Gen- 
eral.) 51a.  Udden  and  Phillips,  Univ.  Tex.,  Bull.  246,  1912.  (Wichita 
and  Clay  counties.)  — United  States:  52.  See  Map  of  Oil  Fields  in 
U.  S.  Geol.  Surv.,  Min.  Res.,  1908,  also  analyses  in  this  and  1907  Min. 
Res.,  as  well  as  Bull.  381-D.  53.  Day,  U.  S.  Geol.  Surv.,  Bull.  394. 
1909.  (Conservation  of  oil  supply.) — Utah:  54.  Richardson,  U.  S. 
Geol.  Surv.,  Bull.  340:  343,  1908.  54a.  Woodruff,  U.  S.  Geol.  Surv., 
Bull.  471:  76,  1912.  (San  Juan  field.)  —  Washington:  55.  Landes, 
Wash.  Geol.  Surv.,  I:  207.  (General.).  55a.  Lupton,  U.  S.  Geol. 
Surv.,  Bull.  581,  1914.  (Olympic  penin.)  —  West  Virginia:  56.  White, 
W.  Va.  Geol.  Surv.,  I  a:  1,  1904.  (General.)  57.  White,  Geol.  Soc. 
Amer.,  Bull.  Ill:  187,  1892.  (Mannington  field.) —Wyoming:  58. 
Knight  and  Slosson,  Bull.  4,  Wyo.  School  of  Mines.  (General.)  59. 
Bull.  3.  (Crook  and  Uinta  Cos.)  60.  Bull.  5.  (Newcastle  field.) 

61.  Jamison,  Rept.  State  Geologist,  Bull.  4,  Ser.  B.     (Salt  Creek  field.) 

62.  Knight,  Eng.  and  Min.  Jour.,  LXXII:  358,  628,  1901;  and  LXXIII: 
563,    1902      (General.)     63.  Veatch,    U.    S.    Geol.    Surv.,    Prop.    Pap. 
56,    1907.     (S.  W.  Wyo.)     63a.   Woodruff,    U.  S.    Geol.    Surv.,   Bull. 
452:  1911.     (Lander  Creek.)     636.  Wegemcnn,  U.  S.  Geol.  Surv.,  Bull. 
471 :   56,  1912.     (Powder  River  field.)     63c.  Barnett,  U.  S.  Geol.  Surv., 
Bull.  541 :   49,  1914.     (Douglas  field.)     63d.  Bull.  581-C,  1914.     (Moor- 
croft  field.) 

Canada:  63e.  Clapp,  Can.  Dept.  Mines,  Mines  Branch,  No.  291,  1914. 
(General.)  63/.  Dowling,  Can.  Min.  Inst.,  Bull.  35:  164,  1915.  (Al- 
berta.) 630.  Huntley,  Amer.  Inst.  Min.  Engrs.,  "  Bull.  102:  1333, 
1915.  (Dakota  sand.)  63/i.  Knight,  Ont.  Bur.  Mines,  XXIV,  Pt. 
2,  1915.  (Ont.)  63i.  Malcolm,  Can.  Geol.  Surv.,  Mem.  29-E  and  81. 

REFERENCES    ON    NATURAL   GAS 

64.  Ashburner.  Amer.  Inst.  Min.  Engrs.,  Trans.  XIV:  428.  (Geology 
and  Distribution  in  the  United  States.)  65.  Orton,  Geol.  Soc.  Amer. 
Bull.  I:  87.  (Rock  pressure.)  65a.  Clapp,  Econ.  Geol.,  VIII:  517, 
1913.  (U.  S.)— Alabama:  656.  Munn,  Ala.  Geol.  Surv.,  Bull.  10, 
1911.  (Fayette  field.) —Arkansas:  65c.  Smith,  U.  S.  Geol.  Surv., 
Bull.  541:  23,  1913.  (Ft.  Smith-Poteau  field.)  —  California:  66. 
Watts,  Calif.  Min.  Bureau,  Bull.  3.  (Central  Valley.)  —  Indiana: 
67.  Phinney,  U.  S.  Geol.  Surv.,  llth  Ann.  Rept.,  I:  589,  1891.  68. 
See  also  Ann.  Repts.  Ind.  Geol.  and  Nat.  Hist.  Survey. — Kansas: 
69.  Adams,  U.  S.  Geol.  Surv.,  Bull.  184,  1901.  70.  Haworth,  Kan. 
Geol.  Surv.,  IX,  1908.  (General.)  71.  Orton,  Geol.  Soc.  Amer., 
Bull.  X:  99,  1899.  (lola  field.)  72.  Volumes  on  Mineral  Resources, 
issued  by  Kan.  Geol.  Surv.,  1897-1901. —  Kentucky:  72a.  Munn, 


136  ECONOMIC  GEOLOGY 

U.  S.  Geol.  Sur.,  Bull.  531,  1913.  (Menifee  field.)  726.  Hoeing, 
Ky.  Geol.  Surv.,  Bull.  1,  1904.  (General.) —  Louisiana:  73.  Harris, 
Perrine,  and  Hopper,  La.  Geol.  Surv.,  Bull.  8,  1909.  (Caddo  field.) 
—  New  York:  74.  Orton,  N.  Y.  State  Mus.,  Bull.  30,  1899.  (General.) 

75.  Newland,  N.  Y.  State  Mus.,  Bull.  93:   943.     (New  York.)  —  Ohio: 

76.  Orton,  Ohio  Geol.  Surv.,  I.  3d  ser.:    55.     77.  Orton,  U.  S.  Geol. 
Surv.,  8th  Ann.  Kept.,  II:   475,  1889.  —  Oklahoma:    77a.  Hutchinson, 
Okla.  Geo.  Surv.,  Bull.  2:    94,  1911.  —  Pennsylvania:    78.  Carll  and 
Phillips,  Ann.  Kept.  Pa.  Geol.  Surv.,  1886,  Pt.  II.,  1887.     (General.) 
Also  Ref.  48— Texas:  79.  Adams,  U.  S.  Geol.  Surv.,  Bull.  184,  1901. 

Canada^-  7&u.  Mickle,  Out.  Bur.  Mines,  XIX,  Pt.  I:  149,  1910.  (Kent 
field.)  796.  Same,  Ibid.,  XXIII:  237,  1914.  (Comp.  Ont.  gas.)  Also 
refs.  63e  and  63i,  p.  135. 

REFERENCES    ON    OIL    SHALES 

80.  Branner,  Amer.  Inst.  Min.  Engrs.,  XXX:  537.  (Brazil.)  81.  Carne 
Memoirs,  Dept.  Mines,  and  Agric.  New  South  Wales,  Geology  No.  3: 
(General  treatise.)  82.  Baskerville,  Eng.  and  Min.  Jour.,  LXXXVIII. 
149,  1909.  (General  and  New  Brunswick.)  83.  Steuart,  Econ.  Geol/, 
III:  573,  1908.  (Scotland.)  84.  Ells,  Can.  Min.  Inst.,  Jour.,  X: 
204,  1908.  (New  Brunswick,  Can.);  also  Jour.  Ming.  Soc.  N.  S., 
XV  and  Dept.  Mines  Can.,  Mines  Branch,  Bulls.  Nos.  55  and  1107, 
1910.  (E.  Can.)  84a.  Woodruff  and  Day,  U.  S.  Geol.  Surv.,  Bull. 
581-A,  1914.  (n.  w.  Colo,  and  n.  e.  Utah.) 

REFERENCES    ON    SOLID    AND    SEMISOLID    BITUMENS 

GENERAL.  85.  Dow,  Min.  Indus.,  X:  51,  1902.  (History  of  Asphalt 
Industry.)  86.  Richardson,  The  Modern  Asphalt  Pavement,  2d  ed., 
N.  Y.  1908.  (Wiley  and  Sons.)  (Uses.)  —  ORIGIN.  87.  Adams, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XXXIII:  340,  1903.  (Origin.) 
88.  Day,  Eng.  Record,  XL:  346.  89.  Eldridge,  Econ.  Geol.,  I:  437, 
1906.  (Asphalt  vein  formation.)  90.  Peckham,  Amer.  Phil.  Soc., 
XXXVII:  108.  (Genesis  of  bitumens.) — SPECIAL  PAPERS.  91.  Bai- 
ley and  Ells,  Geol.  Surv.,  Canada,  1876-1877,  384.  (Albertite.)  92. 
Blake,  Amer.  Inst.  Min.  Engrs.,  Trans.  XVIII:  563.  (Uintaite,  Al- 
bertite, and  Grahamite.)  93.  Coleman,  Ontario,  Bur.  Mines,  6th  Ann. 
Rept.,  159,  1897.  (Anthraxolite.)  94.  Bell,  Amer.  Inst.  Min.  Engrs., 
Trans.  XXXVIII:  836,  1907.  (Athabasca  River,  Can.,  tar  sands.)  — 
AREAL.  95.  Cooper,  Calif.  State  Min.  Bureau,  Bull.  16.  (California.) 

96.  Crosby,  Amer.  Naturalist,  XIII:    229.     (Trinidad.)     96a.  Crump, 
Ky.  Geol.  Surv.,  4th  ser.,  I.  Pt.  2:    1053,  1913.     (Ky.  rock  asphalt.) 

97.  Eldridge,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  I:    1901.     (General 
occurrence  in  United  States,  excellent.)     97a.  Ells,  Can.  Dept.  Mines, 
Spec.   Rept.,   281,    1914      (Alberta  bitum.  sands.)     98.  Gosling,   Sch. 
of  M.  Quart.,  XVI:    41.     (Ozokerite.)     99.  Gould,  Okla.  Geol.  Surv., 
Bull.  1,  1908.     100.  Hayes,  U.  S.  Geol.  Surv.,  Bull.  213:   253.     (Bitu- 
minous sandstones,  Pike  Co.,  Ark.)  —  lOOa.  Hovey,  Min.  Wld.,  XXIX: 
237,     1908.     (Manjak,     Barbados.)     1006.  Hutchinson,     Okla.     Geol. 


PETROLEUM,  NATURAL  GAS,  OTHER  HYDROCARBONS  137 

Surv.,  Bull.  2:  28,  1911.  (Okla.)  101.  Lane,  Eng.  and  Min.  Jour., 
LXXIII:  50.  (Mich.)  102.  Merivale,  Eng.  and  Min.  Jour.,  LXVI: 
790,  1898.  (Barbados.)  103.  Peckham,  Pop.  Sci.  Mo.,  LVIII:  225, 
1901.  (Trinidad  and  Venezuela.)  104.  Phillips,  Univ.  of  Tex.  Min. 
Surv.,  Bull  3,  1902.  (Texas.)  105  Taff,  U.  S.  Geol.  Surv.,  Bull. 
380:  286,  1909.  (Graharrite,  s.  e.  Okla.)  106.  Taff  and  Smith,  U. 
S.  Geol.  Surv.,  Bull.  285:  369,  1906.  (Utah  Ozokerite.)  106a.  Robin- 
son, U.  S.  Geol.  Surv.,  Bull,  forthcoming.  107.  Vaughan,  Eng.  and 
Min.  Jour.,  LXXIII:  344.  (Cuba.)  108.  White,  Bull.  Geol.  Soc. 
Amer.,  X:  277,  1899.  (W.  Va,  Grahamite.)  109.  Zuber,  Zeitschr. 
prak.  Geol.,  XII:  41,  1904.  (Galicia  ozokerite.) 


CHAPTER  III 
BUILDING  STONES 

UNDER  this  term  are  included  all  stones  for  ordinary  masonry 
construction,  as  well  as  for  ornamentation,  roofing,  and  flagging. 
The  number  of  different  kinds  used  is  very  great,  and  includes  prac- 
tically all  varieties  of  igneous,  sedimentary,  and  metamorphic  rocks, 
but  a  few  stand  out  prominently  on  account  of  their  widespread 
occurrence  and  durability. 

The  cost  of  a  building  stone  naturally  exerts  decided  influence  on 
its  use.  Since  the  ease  of  splitting  and  dressing  a  stone  influences 
its  cost,  the  texture  is  also  of  importance.  Color  is  another  factor 
in  determining  the  value  of  a  building  stone,  and  this,  together  with 
other  considerations,  sometimes  gets  a  fashion  leading  to  the  wide- 
spread use  of  certain  stones.  This  has  been  well  illustrated  in  the 
eastern  cities  of  the  United  States,  where,  for  many  years,  Connecti- 
cut brownstone  was  in  such  great  demand  for  use  in  building  private 
dwellings  that  much  inferior  stone  was  put  on  the  market.  More 
recently  Indiana  limestone  and  Ohio  sandstone  have  met  the  popular 
fancy,  and  these  two  are  now  used  in  vast  quantities. 

Properties  of  Building  Stones1  (1-10).  —  The  following  prop- 
erties have  an  important  bearing  on  the  value  of  a  building  stone :  — 

Color.  —  The  color  of  rocks  varies  greatly,  and  those  shown  by 
common  building  stones  include  white,  black,  brown,  red,  yellow, 
and  buff,  while  some  are  green,  blue,  or  mottled.  The  color  may 
vary  in  the  same  quarry. 

In  igneous  rocks  the  color  may  be  that  of  the  prevailing  mineral,  as 
in  pink  granite,  where  there  is  an  excess  of  pink  feldspar;  or  it  may  be 
a  composite  due  to  the  blending  of  the  colors  of  several  minerals,  as  in 
the  case  of  ordinary  gray  granite,  where  the  color  results  from  the  mix- 
ture of  black  mica  and  whitish  quartz  and  feldspar.  Sedimentary  rocks 
commonly  owe  their  color  to  ferruginous  cements,  or  to  carbonaceous 
matter.  The  former  give  brown,  yellow,  red,  or  green  colors  depending  on 
the  condition  of  oxidation  and  form  of  combination  of  the  iron,  while  the 
latter  produces  gray,  black,  and  bluish  tints  depending  on  the  araount 
present.  Sandstone  and  limestone  free  from  either  of  these  coloring  agents 
are  nearly  if  not  quite  white. 

1  Only  the  more  important  ones  are  here  considered.  Excellent  detailed  discus- 
sions will  be  found  in  Refs.  2,  9,  30,  41,  43a,  51. 

138 


BUILDING  STONES  139 

Some  stones  change  color  on  exposure  to  the  air.  For  example,  lime- 
stones or  sandstones  containing  carbonaceous  matter  may  bleach;  some 
black  marbles  fade  to  a  white  or  gray;  and  some  red  and  green  roofing 
slates,  as  well  as  a  few  red  granites,  change  color.  Oxidation  of  evenly 
distributed  pyrite  may  change  gray  or  bluish-gray  sandstones  to  buff  color. 
If  the  minerals  responsible  for  such  change  in  color  are  not  uniformly 
distributed,  the  stone  assumes  a  blotchy  appearance,  but  such  changes  are 
not  necessarily  an  indication  of  deterioration. 


FIG.  52.  —  Photomicrograph  of  a  section  of  Granite.     (Photo  loaned  by 
A.  B.  Cushman.) 

Texture.  —  Building  stones  vary  in  their  texture  from  coarse- 
grained granites  and  conglomerates  to  fine-grained  sandstones,  lime- 
stones, and  porphyries. 

Texture  is  an  important  property,  for  it  influences  both  the  dura- 
bility and  the  cost  of  stone.  Other  things  being  equal,  a  fine-grained 
rock  is  not  only  more  durable,  but  splits  better  and  dresses  more  evenly, 
than  a  coarse-grained  rock.  Uneven  texture,  whether  due  to  mineral 
grains  or  cement,  is  undesirable,  since  it  often  causes  uneven  weathering. 

Density.  —  On  the  whole,  dense  stones  resist  weather  better 
than  porous  ones,  but  there  is  great  difference  in  the  density  of 
building  stones. 


140  ECONOMIC  GEOLOGY 

In  general,  though  with  some  exceptions,  igneous  and  metamorphio 
rocks  have  high  density  because  of  the  close  interlocking  of  the  crystal- 
line grains.  Sedimentary  rocks  of  clastic  origin,  on  the  other  hand,  have 
less  closely  fitting  grains,  and  unless  the  latter  are  very  small,  or  the  pores 
well  filled  with  cement,  they  are  apt  to  be  porous. 

The  specific  gravity  of  a  stone  indicates  its  density;    and  from  the 
specific  gravity  the  weight  per  cubic  foot  may  often  be  approximately 
estimated  by  multiplying  it  by  62.5,  the  weight  of  an  equal  volume  of 
water.     While  sufficiently  accurate  for  very  dense  stones,  this  method  is 
liable  to  lead  to  incorrect  results  when  applied  to  very  porous  rocks. 
Following  are  some  average  specific  gravities  of  common  building  stones, 
as  given  by  Hirschwald  (1):    granite,  2.65;    syenite,  2.80;    diabase,   2.80; 
gabbro,  2.95;    serpentine,   2.60;    gneiss,   2.65;    limestone,    2.60;    dolomite, 
2.80;  sandstone,  2.10;  slate,  2.70. 


FIG.  53.  —  Photomicrograph  of  a  section  of  Diabase.     (Photo  loaned  by 
A.  B.  Cushman.) 

Hardness.  —  The  hardness  of  a  building  stone  is  not  necessarily 
dependent  on  the  hardness  of  its  component  minerals,  but  is  largely 
influenced  by  their  state  of  aggregation,  and  to  some  extent  their 
hardness. 

For  example,  a  sandstone  composed  of  quartz  grains,  but  with  little 
cementing  material,  may  be  so  soft  as  to  crumble  easily  in  the  fingers; 
while  a  limestone,  whose  grains  of  soft  carbonate  of  lime  fit  closely  and 


BUILDING   STONES  141 

are  firmly  cemented,  may  be  difficult  to  break  with  a  hammer.  The 
nature  of  the  cement  in  sedimentary  rocks,  that  is,  whether  it  is  lime, 
silica,  or  iron,  will  also  affect  the  hardness  of  the  stone.  Crystalline  rocks 
owa  their  great  hardness  to  the  firm  interlocking  of  the  mineral  grains. 
Tha  abrasive  resistance  (10)  of  a  stone  will  depend  in  part  on  the  state  of 
aggregation  of  the  mineral  particles,  and  in  part  on  the  hardness  of  the 
grains  themselves.  Some  stones  wear  very  unevenly  because  of  their 
irregularity  of  hardness,  and  such  may  be  less  desirable  than  one  which  is 
uniformly  soft. 

No  standard  form  of  abrasion  test  exists,  and  yet  one  should  be  applied 
to  thoss  stones  which  are  used  for  paving,  steps,  or  flooring,  as  well  as  to 
those  placed  in  situatians  where  they  may  be  subjected  to  the  attacks  of 
wind-blown  sand,  or  the  rubbing  action  of  running  water. 

Strength.  —  Two  kinds  of  strength,  compressive  and  transverse, 
are  to  be  considered  in  building  stones. 

The  compressive  or  crushing  strength,  which  is  expressed  in  pounds- 
per  square  inch,  is  the  resistance  which  the  rock  offers  to  a  crushing 
force,  and  is  dependent  chiefly  on  the  size  of  the  grains,  state  of  aggrega- 
tion, and  mineral  composition.  Because  of  the  close  interlocking  of  the 
grains  of  igneous  rocks  they  are  stronger  than  those  of  sedimentary  origin, 
in  which  the  strength  is  due  chiefly  to  the  cement  which  binds  the  grains 
together.  Sedimentary  rocks  show  greatest  strength  when  dry,  or  when 
pressure  is  applied  at  right  angles  to  the  bedding. 

Few  building  stonss  when  in  use  are  subjected  to  pressures  even  approxi- 
mately equal  to  their  crushing  strength.  No  domestic  building  stone  at 
present  used  in  the  eastern  market  has  a  crushing  strength  of  less  than  6000 
pounds,  yet  the  pressure  even  in  the  tallest  buildings  does  not  require 
a  stone  with  a  crushing  strength  exceeding  314.6  pounds,  and  this  includes 
the  factor  of  safety  of  twenty  usually  allowed  by  architects.  Computa- 
tions show  that  a  stone  at  the  base  of  the  Washington  monument  sustains 
a  maximum  pressure  of  6292  pounds  per  square  inch,  which  includes  the 
usual  factor  of  safety  of  twenty;  the  crushing  strength  of  the  stone  used 
in  the  base  of  the  monument  is  however  not  less  than  10,000  to  12,000 
pounds  per  square  inch. 

The  crushing  strength  of  some  soft  limestones  or  sandstones  may  be 
but  little  above  3000  pounds  per  square  inch,  while  that  of  diabase  often 
exceeds  30,000  pounds  per  square  inch.  The  accompanying  table  gives 
the  crushing  strength  of  a  number  of  stones.  (Many  others  are  given  in  the 
state  reports.) 

CRUSHING  STRENGTH  OF  BUILDING  STONES 

Granite,  Vinal  Haven,  Me 13,381 

Granite,  East  Saint  Cloud,  Minn 28,000' 

Granite,  Port  Deposit,  Md 19,750 

Dolomite  marble,  Tuckahoe,  N.Y 13,076 

Limestone,  Caen,  France 3,550 

Sandstone,  Portland,  Conn 13,310 

Sandstone,  E.  Long  Meadow,  Mass 8,812 


142 


ECONOMIC   GEOLOGY 


Wide  variations  sometimes  exist  in  stones  from  different  parts  of  the 
same  quarry,  or  in  stones  from  the  same  locality  tested  at  different  times. 
The  published  crushing  tests  of  different  stones  cannot  really  be  fairly 
compared  because  all  have  not  been  tested  under  exactly  the  same  condi- 
tions. 

Transverse  Strength.  —  The  transverse  strength  is  the  load  which  a 
bar  of  stone,  supported  at  both  ends,  is  able  to  withstand  without  break- 
ing. It  is  measured  in  terms  of  the  modulus  of  rupture,  which  represents 
the  force  necessary  to  break  a  bar  of  one  square  inch  cross  section,  rest- 
ing on  supports  one  inch  apart,  the  load  being  applied  in  the  middle. 


FIG.  54. —  Photomicrograph  of  a  section  of  quartzitic  sandstone. 
(Photo  loaned  by  A.  B.  Cushman.) 

Although  stones  in  buildings  are  rarely,  if  ever,  crushed,  they  are  frequently 
broken  transversely,  and  therefore  a  knowledge  of  the  transverse  strength 
is  of  more  importance  than  the  crushing  strength.  A  high  crushing  strength 
does  not  necessarily  mean  a  high  transverse  strength.  Unfortunately 
few  stones  have  been  tested  in  this  manner. 

Porosity  and  Ratio  of  Absorption.  —  The  porosity  of  building 
stones  varies  widely.  Most  igneous  rocks  have  little  pore  space 
and  hence  absorb  little  water;  but  sedimentary  rocks,  especially 
sandstones,  are  often  very  porous. 

Many  rocks,  especially  those  of  the  sedimentary  class,  contain  water 
in  their  pores  when  first  quarried.  This  is  known  to  quarrymen  as  quarry 


BUILDING   STONES  143 

water,  and  it  is  present  in  some  porous  sandstones  in  sufficient  quantities 
to  interfere  with  quarrying  during  freezing  weather.  Mineral  matter  in 
solution  in  the  quarry  water  is  deposited  between  the  grains  when  the  water 
evaporates,  often  in  sufficient  quantities  to  perceptibly  harden  the  stone. 

Water  is  also  present  in  the  joint  planes,  and  by  its  passage  along  these 
planes  causes  oxidation  and  rusting  of  the  iron  of  the  rock-forming  minerals. 
This  discolors  the  stone  along  and  on  either  side  of  the  joint  planes,  giving 
rise  to  a  yellow  color  known  as  sap. 

Resistance  to  Frost.  —  Building  stones  show  a  varying  degree  of 
resistance  to  frost. 

Dense  rocks,  like  granites,  quartzites,  and  many  limestones,  and  even 
some  very  porous  rocks,  are  little  affected;  but  many  porous  and  lami- 
nated rocks,  like  open  sandstones  and  schists,  disintegrate  under  frost 
action.  This  is  due  to  the  fact  that  moisture  absorbed  in  the  warmer 
weather,  on  freezing  in  the  pores,  expands,  and  either  forces  off  small 
pieces  or  disrupts  the  stones.  Since  clay  readily  absorbs  water,  clayey 
rocks  are  sometimes  similarly  affected. 

Resistance  to  Heat.  —  All  rocks  expand  when  heated,  and  con- 
tract when  cooled,  but  do  not  shrink  down  to  their  original  dimen- 
sions. This  permanent  increase  in  size  is  termed  permanent  swell- 
ing, and  though  small  when  figured  for  one  linear  foot,  is  appreciable 
in  long  pieces. 

The  following  figures  give  the  average  of  a  number  of  tests  of  permanent 
swelling  in  stone  bars  20  inches  long,  heated  from  32°  F.  to  212°  F.,  and 
then  cooled  to  the  original  temperature:  granite,  .009  inch;  marble, 
.009  inch;  limestone  and  dolomites,  .007  inch;  sandstone,  .0047. 

The  most  severe  test  of  a  stone's  resistance  to  rapid  changes  of  tempera- 
ture is  to  heat  it  to  about  800°  C.  and  then  immerse  it  in  cold  water. 
Quartzites  and  hard  sandstones  withstand  such  treatment  best;  some  gran- 
ites crack  and  crumble,  and  the  carbonate  rocks  change  to  lime. 

Chemical  Composition.  —  Many  chemical  analyses  of  building 
stones  have  been  made,  but  most  of  them  are  of  little  value,  largely 
because  they  tell  us  nothing  regarding  the  physical  properties  of  the 
stone.  They  are  perhaps  of  most  value  in  the  case  of  sedimentary 
rocks.  The  chemical  analysis  of  a  limestone  will  indicate  whether 
it  is  dolomitic  or  not,  also  whether  it  is  clayey  in  its  character.  So 
too  the  analysis  of  a  sandstone  will  indicate  whether  it  is  siliceous 
or  clayey. 

Life  of  a  Building  Stone.  —  This  may  be  considered  as  the  period 
of  time  a  stone  will  stand  exposure  to  the  weather  without  showing 
signs  of  decay.  Even  for  the  same  stone,  it  may  vary  with  location 


144  ECONOMIC   GEOLOGY 

and  climate.     Julien  makes  the  following  deductions  from  observa- 
tions made  on  stones  in  use :  — 

Coarse  brownstone .  5-15  years 

Fine-laminated  brownstone .     .  20-50  years 

Coarse  fossiliferous  limestone      .     .     .     .     .     .     •»     ...  20-40  years 

Coarse  dolomi tic  marble •  •.-,.    . , -_.  ?.  40  years 

Fine-grained  marble -v-    .-.    '?£'$    •  50-100  years 

Granite V."  .     .     .     .  75-200  years 

Quartzite V '.....     .  75-200  years 

Structural  Features  affecting  Quarrying.  —  All  rocks  are  traversed  by 
planes  of  separation  of  one  sort  or  another.  In  sedimentary  rocks  these 
consist  of  bedding  and  joint  planes;  in  igneous  rocks,  the  latter  alone 
are  present;  and  in  metamorphic  rocks,  joint  planes,  a  banding  of  minerals 
and,  very  often,  cleavage  planes. 

Bedding  planes.  —  (PL  XVII,  and  PI.  XXII,  Fig.  1.)  These  may  be 
either  an  advantage  or  a  disadvantage  to  the  quarryman.  They  are  desir- 
able because  they  facilitate  the  extraction  of  the  stone;  but  if  numerous 
and  closely  spaced,  the  layers  may  be  too  thin  for  any  purpose  except 
flagging.  They  often  serve  as  a  means  of  entrance  for  the  agents  of  weather- 
ing, and  the  stone  may  be  disintegrated  along  the  bedding  planes  v.hile 
elsewhere  fresh. 

Incipient  planes  of  weakness,  due  either  to  the  arrangement  of  minerals 
or  to  microscopic  fractures  in  them,  often  give  rise  to  planes  of  easy  splitting 
which  are  of  great  value  in  quarrying,  notably  of  granite.  The  most  promi- 
nent plane  is  called  rift;  and  a  less  prominent  vertical  plane,  approxi- 
mately at  right  angles  to  the  rift,  is  called  the  grain.  Granites  often 
show  a  sheeted  (PI.  XVI,  Fig.  1)  structure,  due  to  the  presence  of  horizontal 
joints.  These  are  slightly  curved,  and  hence  tend  to  separate  the  granite 
mass  into  a  series  of  lenses. 

The  position  of  the  beds  exerts  an  important  influence  on  the  cost 
of  quarrying.  When  horizontal  and  of  different  quality,  it  may  often 
be  necessary  to  strip  off  worthless  rock  in  order  to  reach  the  beds  of  good 
quality.  In  such  cases,  there  is  often  less  stripping  to  do  in  quarries  opened 
on  gently  sloping  ground.  In  regions  of  steep  dip,  it  is  sometimes  possible 
to  work  the  quarry  as  a  cut,  extracting  the  desired  beds  and  leaving  useless 
ones  standing. 

GRANITES 

Characteristics  of  Granites  (9,  43 a).  —  As  commonly  used  by 
quarrymen,  the  term  granite  includes  all  igneous  rocks  and  gneiss; 
but  in  this  book  it  is  used  in  the  geological  sense,  which  is  more 
restricted.  From  the  geological  standpoint  a  granite  is  a  holocrys- 
talline,  plutonic  igneous  rock  consisting  of  quartz,  orthoclase  feld- 
spar, and  either  mica  or  hornblende,  or  both.  There  are  also  varying 
but  usually  small  quantities  of  other  feldspars,  and  there  may  be 


PLATE  XVI 


FIG.  1.  —  Granite  quarry,  Hardwick,  Vt.     (Photo,  by  G.  H.  Perkins.) 


FIG.  2.  —  Quarry  in  volcanic  tuff,  north  of  Phcenix,  Ariz. 


(145) 


146  ECONOMIC   GEOLOGY 

subordinate  accessory  minerals,  such  as  pyrite,  garnet,  tourmaline, 
and  epidote. 

Granites  vary  in  texture  from  fine  to  coarse  grained,  and  in  some 
cases  are  porphyritic.  They  pass  into  gneisses  by  such  insensible 
gradations  that  no  sharp  line  can  be  drawn  between  the  two.  In 
color  they  vary,  being,  most  commonly,  gray,  mottled  gray,  red, 
pink,  white,  or  green,  according  to  the  color  or  abundance  of  the 
component  minerals.  Most  granites  are  permanent  in  their  color, 
but  some  of  bright  red  color  bleach  on  continuous  exposure  to  sun- 
light. 

The  average  specific  gravity  of  granites  is  2.65,  which  corresponds  to  a 
weight  of  165.6  pounds  per  cubic  foot.  They  commonly  contain  less  than 
1  per  cent  of  water,  and  often  absorb  two  or  three  tenths  more.  Their 
crushing  strength  varies,  but  is  apt  to  lie  between  15,000  and  30,000  pounds 
per  square  inch. 

Granites  are  among  the  most  durable  of  building  stones,  but  there  is  some 
variation  in  the  durability  of  the  different  kinds.  Other  things  being 
equal,  fine-grained  granites  are  more  durable  than  coarse-grained,  being  less 
easily  affected  by  changes  of  temperature.  One  of  the  most  beautiful 
granites  known,  the  Rapikivi  granite  of  Finland,  lacks  in  durability  on  this 
account.  Pyrite  and  marcasite  are  injurious  minerals,  since  they  rust  rap- 
idly and  may  discolor  the  stone  in  an  unsightly  manner.  Very  few  granites 
now  in  use  show  signs  of  decay;  but  in  those  that  do,  the  darker  silicates 
are  rusted,  the  luster  of  the  feldspar  is  dulled,  and,  in  some  cases,  the  stone 
has  begun  to  disintegrate. 

Distribution  of  Granites  in  the  United  States  (9).  —  Granite 
usually  occurs  in  batholytic  masses  sometimes  forming  the  cores  of 
mountain  chains.  Removal  of  the  overlying  strata  by  denudation 
has  revealed  the  granite,  which,  owing  to  its  greater  durability,  is 
often  left  standing  as  peaks  or  domes  by  the  farther  removal  of  the 
surrounding,  weaker  strata.  Granites  show  a  wide  geologic  range, 
but  most  known  occurrences  are  associated  with  the  older  forma- 
tions. 

Granite  forms  an  important  source  of  durable  building  stone 
widely  distributed  in  the  United  States  (Fig.  55) ;  but  nearly  70  per 
cent  of  that  quarried  comes  from  the  Atlantic  states.  There  are 
several  areas  which  will  be  briefly  considered. 

Eastern  Crystalline  Belt  (2, 11,  19,  26,  31,  44,  45).  —  From  north- 
eastern Maine  southwestward  to  eastern  Alabama  there  is  an  im- 
portant belt  of  granites  and  gneisses,  mostly  of  pre-Cambrian  age. 
Those  at  the  northeastern  end  of  the  belt,  as  far  south  as  New 
York,  are  most  extensively  quarried,  largely  because  of  their  pecul- 


BUILDING  STONES 


147 


iarly  favorable  location.  In  this  belt  those  of  Quincy,  Massachu- 
setts (28),  Barre,  Vermont  (44),  and  Westerly,  Rhode  Island  (41), 
are  of  value  for  monumental  work.  Many  large  quarries  have  also 
been  opened  up  in  Maine  (25a)  ,but  their  output  is  employed  mainly 
for  structural  work.  A  gneissic  granite  quarried  at  Port  Deposit, 
Maryland  (26),  a  white  granite  from  Mt.  Airy,  North  Carolina  (36), 
as  well  as  a  pinkish  granite  worked  at  Stone  Mountain,  Georgia  (20), 
are  also  of  some  importance.  Another  important  granite  area  is 
located  near  Richmond,  Virginia.  (46). 


FIG.   55.  —  Map   showing   distribution   of   crystalline  rocks    (mainly  granites)  in 
United  States.     (After  Merrill,  Stones  for  Building  and  Decoration.) 

Minnesota-Wisconsin  Area  (51).  —  There  are  several  detached 
areas  in  these  two  states,  some  of  which  supply  granites  of  value  for 
ornamental  work.  That  from  Montello,  Wisconsin,  bears  a  high 
reputation,  and  those  from  Wausau,  Wisconsin,  and  Ortonville, 
Minnesota,  are  favorably  known. 

Southwestern  Area.  —  This  includes  portions  of  Missouri,  Arkan- 
sas, Oklahoma,  and  Texas. 

These  four  states  contain  small  areas,  worked  mainly  to  supply  a 
local  demand.  Those  of  southeastern  Missouri  vary  from  light  gray 
to  red  in  color  and  fine  grained  to  porphyritic  in  texture.  Some  of 
the  rock  is  rhyolite.  The  region  around  Fredericktown  is  important 
(30).  Important  granite  deposits  are  known  in  the  Arbuckle  and 
Wichita  Mountains  of  Oklahoma  (38),  but  their  development  thus 


148  ECONOMIC  GEOLOGY 

far  has  been  slight.  Arkansas  contains  quarries  of  syenite  west  of 
Little  Rock  (2),  and  for  purposes  of  convenience  it  is  mentioned 
under  granite.  In  Texas  quarries  have  been  opened  in  Llano 
County,  and  yield  both  pink  and  gray  granite  (2,  43a). 

Western  States.  —  There  are  many  areas  of  true  granite,  and 
closely  allied  rocks  such  as  grano-diorite  and  rhyolite  in  the  western 
states.  The  central  portion  of  the  Black  Hills  of  South  Dakota  is 
a  great  granite  mass,  but  little  of  it  is  quarried.  Granites  are  known 
in  Colorado  (17),  and  quarried  to  some  extent,  and  the  rhyolites  of 
Castle  Rock  are  of  considerable  importance.  In  California  the 
grano-diorite  mass  forming  the  central  portion  of  the  Sierra  Nevada 
Mountains  yields  an  inexhaustible  supply,  which  is  quarried  at 
several  points.  Montana,  Washington  (48),  and  Oregon  also  con- 
tain granites  which  are  quarried  for  local  use.  On  the  whole,  how- 
ever, the  Cordilleran  granite  industry  is  somewhat  restricted  be- 
cause of  lack  of  demand. 

Uses  of  Granite.  —  On  account  of  its  massive  character  and 
durability,  granite  is  much  employed  for  massive  masonry  construc- 
tion, while  some  of  the  granites  that  take  and  preserve  a  high  polish, 
and  are  susceptible  of  being  carved,  are  in  great  demand  for  orna- 
mental and  monumental  work.  Because  of  its  greater  durability, 
granite  has  in  recent  years  largely  replaced  marble  for  monumental 
purposes. 

The  refuse  of  the  quarries  is  often  dressed  for  paving  blocks  or 
crushed  for  roads  and  railroad  ballast.  The  size  of  the  blocks 
which  can  be  extracted  from  a  granite  quarry  depends  in  part  on  the 
spacing  of  the  joint  planes,  in  part  on  the  perfection  of  development 
of  the  rift,  some  of  the  monoliths  that  have  been  quarried  being  of 
immense  size:  for  example,  one  from  Stony  Creek,  Connecticut, 
measured  41  ft.  X  6  ft.  X  6  ft.;  one  from  Vinal  Haven,  Maine,  60  ft. 
X  5£  ft.;  one  from  Barre,  Vermont,  60  ft.  X  7  ft.  X  6  ft. 

Miscellaneous  Igneous  Rocks  (9).  —  But  little  space  need  be 
given  to  these,  for  they  are  of  minor  importance  as  compared  with 
the  granites.  In  the  eastern  states  the  diabase  or  trap  rock  is 
quarried  at  several  points  in  Connecticut,  New  York,  New  Jersey, 
and  Pennsylvania.  Owing  to  its  great  hardness  it  is  only  occasion- 
ally used  for  dimension  blocks,  its  chief  value  being  for  paving 
blocks  and  road  metal.  The  basaltic  rocks  of  the  western  states, 
especially  those  of  Washington  and  California,  are  often  employed 
for  similar  purposes.  Anorthosites  and  gabbros,  some  of  the  former 
being  of  highly  ornamental  character  when  polished,  occur  in  the 


BUILDING   STONES  149 

Adirondack  Mountains,  New  York;  they  are,  however,  but  little 
utilized.  Gabbros  have  been  quarried  for  local  use  in  Maryland  and 
Minnesota,  and  diorites  have  been  quarried  to  a  small  extent  at 
scattered  localities.  Some  of  the  porphyries  and  rhyolites  of  the 
Atlantic  states  possess  considerable  beauty  when  polished.  A 
handsome  porphyry  is  quarried  in  Wisconsin  (51),  and  in  the  Cor- 
dilleran  region  both  rhyolite  and  porphyry  occur  in  numerous  lo- 
calities. Andesite  tuffs  are  quarried  in  Colorado,  and  consolidated 
volcanic  tuffs  have  also  been  used  to  some  extent  for  building  in 
Arizona. 

LIMESTONES    AND    MARBLES 

General  Characteristics  (l,  9).  —  A  great  series  of  sedimentary 
and  metamorphic  rocks,  composed  chiefly  of  carbonate  of  lime,  or, 
in  the  case  of  dolomite,  of  carbonate  of  lime  and  magnesia,  is  included 
under  the  term  limestone  and  marble.  These  rocks  also  contain 
varying,  but  usually  small,  amounts  of  iron  oxide,  iron  carbonate, 
silica,  clay,  and  carbonaceous  matter.  When  of  metamorphic 
character  various  silicates,  such  as  mica,  hornblende,  and  pyroxene, 
etc.,  may  be  present. 

These  calcareous  rocks  vary  in  texture  from  fine-grained,  earthy, 
to  coarse-textured,  fossiliferous  rocks,  and  from  finely  crystalline  to 
coarsely  crystalline  varieties.  There  is,  also,  great  range  in  color, 
the  most  common  being  blue,  gray,  white,  and  black,  but  beautiful 
shades  of  yellow,  red,  pink,  and  green,  usually  due  to  iron  oxides, 
are  also  found.  Their  crushing  strength  commonly  ranges  from 
10,000  to  15,000  pounds  per  square  inch,  while  their  absorption  is 
generally  low. 

The  mineral  composition  of  limestone  exerts  a  strong  influence  on 
its  durability.  Those  limestones  which  are  composed  chiefly  or 
wholly  of  carbonate  of  lime  are  liable  to  solution  in  waters  contain- 
ing carbon  dioxide;  but  dolomite  limestones,  especially  coarse- 
grained ones,  disintegrate  rather  than  decompose.  Streaks  of 
mineral  impurities  cause  the  stone  to  weather  unevenly.  Pyrite 
is  an  especially  injurious  constituent,  not  only  on  account  of  its 
rusting,  but  also  because  the  sulphuric  acid  set  free  by  its  decompo- 
sition attacks  the  stone.  Tremolite,  which  is  found  in  some  dolo- 
mitic  marbles,  is  also  liable  to  cause  trouble  by  its  decay.  Black  or 
gray  limestones  will  sometimes  bleach  on  exposure. 

Varieties  of  Limestones.  —  In  the  geological  sense  limestones  are  of 
sedimentary  origin,  while  marbles  are  of  metamorphic  character,  but  in  the 


150  ECONOMIC   GEOLOGY 

trade  the  term  marble  is  applied  to  any  calcareous  rock  capable  of  taking  a 
polish.  In  addition  to  the  different  varieties  of  marble  and  the  ordinary 
limestones,  there  are  certain  kinds  of  calcareous  rock  to  which  special 
names  are  given,  as  follows :  — 

Chalk  is  a  fine,  white,  earthy  limestone,  composed  chiefly  of  foraminiferal 
remains. 

Coquina  is  a  loosely  cemented  shell  aggregate,  like  that  found  near  St. 
Augustine,  Florida. 

Dolomite,  or  dolomitic  limestone,  composed  of  carbonate  of  lime  and 
magnesia,  and  to  the  eye  alone  often  is  indistinguishable  from  limestone. 

Fossiliferous  limestones  is  a  general  term  applied  to  those  limestones 
which  contain  many  fossil  remains.  Under  this  heading  are  included  cri- 
noidal  limestone  and  coral-shell  marble. 

Hydraulic  limestone,  an  argillaceous  limestone  containing  over  10  per 
cent  of  clayey  impurities.  Used  mainly  for  cement  manufacture  (p.  188). 

Lithographic  limestone  is  an  exceedingly  fine  grained,  crystalline  limestone, 
of  gray  or  yellowish  hue.  It  is  used  for  lithographic  and  not  structural  work. 

Oolitic  limestone,  composed  of  small,  rounded  grains  of  concretionary 
character. 

Stalactitic  and  stalagmitic  deposits,  formed  on  the  roofs  and  floors  of 
caves,  respectively,  are  often  of  crystalline  texture  and  beautifully  colored, 
and,  when  of  sufficient  solidity,  are  known  as  onyx  marble. 

Travertine,  or  calcareous  tufa,  a  limestone  deposited  from  springs.  The 
Roman  deposits  are  sufficiently  hard  for  building  purposes,  but  those  occurring 
in  the  United  States,  as  in  Virginia,  are  not  so,  even  though  the  deposits 
are  large. 

Distribution  of  Limestones  in  the  United  States.  —  Limestones 
are  found  in  many  states,  and  in  all  geological  formations  from 
Cambrian  to  Tertiary,  but  those  of  the  Paleozoic,  which  are  much 
used  in  the  eastern  and  central  states,  are  more  extensive  and  more 
massive  than  those  of  later  formations.  Although  many  large 
quarries  have  been  opened  to  supply  a  local  demand,  the  product  is 
shipped  to  a  distance  from  only  a  few  localities.  At  present  the 
Subcarboniferous  Bedford  (22)  oolitic  limestone  of  Indiana  (PL 
XVII)  is,  perhaps,  the  most  widely  used  limestone  in  the  United 
States.  It  occurs  in  massive  beds  from  20  to  70  feet  thick,  and  is 
said  to  underlie  an  area  of  more  than  70  square  miles.  Although 
soft  and  easily  dressed,  it  has  good  strength,  and  has  been  used  in 
many  important  cities  of  the  United  States.  The  same  rock  is 
quarried  at  Bowling  Green,  Ky.  (23c). 

In  the  eastern  and  central  states  the  Paleozoic  limestones  are 
worked  at  many  points,  mainly  to  supply  a  local  demand  (3). 

Cretaceous  limestones  are  worked  in  Kansas,  Nebraska,  and 
Iowa,  although  the  most  important  sources  are  in  the  Paleozoic 
formations. 


pq 


152 


ECONOMIC   GEOLOGY 


Distribution  of  Marbles  in  the  United  States  (2). — While  some 
variegated  marbles  are  produced  in  the  United  States,  still  most  of 
those  quarried  are  white,  the  greater  part  of  the  variegated  stones 


FIG.  56.  —  Map  showing  marble  areas  of  eastern  United  States.     (After  Merrill, 
Stones  for  Building  and  Decoration.) 

being  imported.  The  main  supply  comes  chiefly  from  regions  of 
metamorphic  rock,  the  eastern  crystalline  belt  being  the  principal 
producer  (Fig.  56).  Vermont  (44,45)  leads  all  other  states  in 
marble  production,  supplying  a  large  per  cent  of  all  the  marbles 

i 


BUILDING  STONES  153 

used  for  ornamental  work  in  the  country.  The  most  important  and 
largest  quarries  are  those  at  Proctor  (PL  XVIII)  and  West  Rutland. 
At  the  latter  locality  the  marble  bed  has  a  thickness  of  150  feet  at 
the  top  of  the  quarry,  narrowing  to  75  feet  at  the  bottom,  and  is 
divisible  into  a  series  of  well-marked  layers  of  varying  thickness, 
quality,  and  color  (45). 

The  Vermont  marbles  usually  show  a  bluish-gray  or  whitish 
ground,  the  latter  often  showing  a  pinkish  or  creamy  shade,  and 
traversed  by  veins  or  markings  of  a  green  or  brown  color. 

A  beautifully  colored  series  of  variegated  marbles  *  is  quarried  at 
Swanton,  Vt.  (45),  and  much  used  throughout   the  United  States 
for  flooring  and  wainscoting.     Owing  to  their  highly  siliceous  char- 
acter they  show  excellent  wearing  qualities.     White  marbles  for 
structural  work  are  quarried  at  Lee,  Massachusetts  (2),  and  at 
South  Dover  and  Gouverneur,  New  York  (2,  35),  but  gray  ones 
are  also  obtained  from  the  last-named  locality.     In  Maryland 
important  quarries  have  been  opened  up  at  Cockeysville  (26). 
Large  quantites  of  white  and  also  gray  marble  are  quarried  in 
Pickens  County,  Georgia  (19)  (PL  XIX,  Fig.  1). 

The  Trenton  limestone  in  eastern  Tennessee  (9)  supplies  marble 
of  gray,  and  of  pinkish  chocolate  color  with  white  variegation. 
It  is  used  chiefly  for  interior  decoration.  The  Napoleon  gray  from 
Phenix,  Missouri,  is  very  similar  to  the  Knoxville,  Tenn.,  gray. 

Marble  has  been  reported  from  various  other  states  west  of 
the  Mississippi,  but  as  yet  little  quarry 'ng  has  been  done.  A 
large  deposit  of  white  marble  is  said  to  occur  at  Marble,  Colorado, 
and  that  quarried  in  Inyo  County,  California,  has  attracted  con- 
siderable attention  in  recent  years  (16). 

Most  of  the  variegated  marble  used  for  interior  decoration  in  this  coun- 
try is  obtained  from  foreign  countries,  especially  France,  Belgium,  Greece, 
etc.  Many  of  these  imported  stones  are  of  rare  beauty,  but  are  usually 
unfitted  for  exterior  use  in  severe  climates,  a  fact  often  ignored  by  architects. 
Although  ornamental  stones  of  this  class  occur  in  the  United  States,  up  to 
the  present  time  few  attempts  have  been  made  to  place  them  on  the  market. 
This  may  be  due  to  the  fact  that  most  quarrymen  do  not  care  to  assume  the 
temporary  expense  which  their  introduction  might  involve. 

Onyx  Marbles  (53-56).  —  Under  this  term  are  included  two  types  of 
calcareous  rock,  one  a  hot-spring  deposit,  or  travertine,  formed  at  the 
surface,  the  other  a  cold-water  deposit  formed  in  limestone  caves  in  the 
same  manner  as  stalagmites  and  stalactites.  Cave  onyx  is  more  coarsely 
crystalline  and  less  translucent  than  travertine  onyx.  The  beautiful 

1  These  should  perhaps  be  more  properly  classed  as  calcareous  sandstones. 


154  ECONOMIC   GEOLOGY 

banding  of  onyx  is  due  to  the  deposition  of  successive  layers  of  carbonate 
of  lime,  while  the  colored  cloudings  and  veinings  are  caused  by  the  presence 
of  metallic  oxides,  especially  iron. 

Neither  variety  of  onyx  occurs  in  extensive  beds,  though  both  are  widely 
distributed.  Onyx  is  found  in  Arizona,  California,  and  Colorado,  but  it 
has  not  been  developed  in  any  of  these  states  except  on  a  small  scale. 
Most  of  the  onyx  used  in  the  United  States  is  obtained  from  Mexico,  though 
small  quantities  are  obtained  from  Egypt  and  north  Algeria. 

The  value  of  onyx  varies  considerably,  the  poorer  grades  selling  for 
as  little  as  50  cents  per  cubic  foot,  while  the  higher  grades  bring  $50  or  more. 
The  earliest-worked  deposits  were  probably  those  of  Egypt,  which  were  used 
by  the  ancients  for  the  manufacture  of  ornamental  articles  and  religious 
vessels;  and  the  Romans  obtained  onyx  from  the  quarries  of  northern  Al- 
geria. Many  of  the  travertine  onyx  deposits  occur  in  regions  of  recent  vol- 
canic activity,  and  all  of  the  known  occurrences  are  of  recent  geological  age. 

Uses  of  Limestones  and  Marbles.  —  The  limestones  are  used 
mainly  for  ordinary  dimension  blocks,  though  some,  as  the  Bedford 
stone,  lend  themselves  well  for  carved  work.  The  refuse  from  the 
quarry  may  be  of  value  for  road  material,  lime,  or  Portland  cement 
manufacture.  (See  reference  under  Cement.) 

Marbles  are  used  in  increasing  quantities  for  ordinary  structural 
work,  although  many  of  the  lighter-colored  ones  soon  become  soiled 
by  dust  and  smoke.  The  output  of  many  quarries,  especially  the 
Vermont  ones,  is  well  adapted  to  monumental  purposes,  and  these, 
together  with  those  from  Georgia,  Tennessee,  and  California,  are 
much  used  for  wainscoting  and  paneling.  That  from  Swanton  is 
also  well  adapted  to  flooring.  Electrical  switchboards  are  now 
frequently  made  of  marble.  The  demand  for  marble  tops  for 
tables,  washbasins,  and  similar  uses  is  probably  decreasing.  The 
refuse  from  marble  quarries  is  sometimes  utilized  for  the  same  pur- 
poses as  limestone.  Special  tests  are  applied  to  marbles  (45a) . 

SERPENTINE 

Pure  serpentine  is  a  hydrous  silicate  of  magnesia;  but  beds  of  serpentine 
are  rarely  pure,  usually  containing  varying  quantities  of  such  impurities 
as  iron  oxides,  pyrite,  hornblende,  and  carbonates  of  lime  and  magnesia. 
The  purer  varieties  are  green  or  greenish  yellow,  while  the  impure  types  are 
various  shades  of  black,  red,  or  brown.  Spotted  green  and  white  varieties 
are  called  ophiolite  or  ophicalcite. 

Serpentine  is  sometimes  found  in  sufficiently  massive  form  for  use  in 
structural  or  decorative  work;  but,  owing  to  the  frequent  and  irregular 
joints  found  in  nearly  all  serpentine  quarries,  it  is  difficult  to  obtain  other 
than  small-sized  slabs.  Its  softness  and  beautiful  color  have  led  to  its 
extensive  use  for  interior  decoration;  but  since  it  weathers  irregularly  and 
loses  luster,  it  is  not  adapted  to  exterior  work. 


PLATE  XVIII.  —  Marble  quarry,  Proctor,  Vt.  The  banding  of  the  rock  is  vertical 
The  horizontal  lines  are  caused  by  the  stone  being  quarried  in  benches. 
(Photo.,  Vermont  Marble  Co.) 

(155) 


156  ECONOMIC  GEOLOGY 

Though  found  in  a  number  of  states,  most  of  the  numerous  attempts 
to  quarry  American  serpentine  have  been  unsuccessful.  Considerable 
serpentine  for  ordinary  structural  work  has  been  quarried  in  Chester 
County,  Pennsylvania,  and  a  variety  known  as  verdolite  has  been  worked 
near  Easton,  Pennsylvania  (32).  Quarrying  operations  have  also  been 
carried  on  in  the  state  of  Washington  (48),  Maryland  and  Georgia. 


SANDSTONES 

General  Properties  (1,  9).  — While  most  sandstones  are  com- 
posed chiefly  of  quartz  grains,  some  varieties  contain  an  abundance 
of  other  minerals,  such  as  mica,  or,  more  rarely,  feldspar,  which  in 
rare  cases  may  even  form  the  predominating  mineral.  Pyrite  is 
occasionally  present,  and  varying  amounts  of  clay  frequently  occur 
between  the  grains,  at  times  in  sufficient  quantity  to  materially 
influence  the  hardness  and  dressing  qualities  of  the  stone.  The 
hardness  of  sandstones,  however,  usually  depends  on  the  amount 
and  character  of  the  cement,  varying  from  those  having  so  small 
an  amount  of  silica  or  iron  oxide  cement  that  the  stone  crumbles  in 
the  fingers  to  those  quartzites  whose  grains  are  so  firmly  bound  by 
silica  that  the  rock  resembles  solid  quartz.  With  these  differences 
the  chemical  composition  varies  from  nearly  pure  silica  to  sandstone 
with  a  large  percentage  of  other  compounds.  (For  analyses,  see 
Kemp's  "  Handbook  of  Rocks.") 

There  are  many  colors  among  sandstones,  but  light  gray,  white, 
brown,  buff,  bluish  gray,  red,  and  yellow  are  most  common.  In 
density  sandstones  range  from  the  nearly  impervious  quartzites  to 
the  porous  sandrocks  of  recent  geologic  formations,  and  conse- 
quently they  show  a  variable  absorption.  Most  sandstones  con- 
tain some  quarry  water,  and  those  with  appreciable  amounts  are 
softer  and  more  easy  to  dress  when  first  quarried;  but  they  cannot 
be  quarried  in  freezing  weather.  The  average  specific  gravity  of 
sandstone  is  2.7,  and  accordingly  a  cubic  foot  weighs  about  160  to 
170  pounds. 

On  the  whole,  sandstones  resist  heat  well  and  are  usually  of  ex- 
cellent durability,  since  they  contain  few  minerals  that  decompose 
easily.  When  they  disintegrate,  it  is  commonly  by  frost  action. 
The  injurious  minerals  are  pyrite,  mica,  and  clay.  Pyrite  is  likely 
to  cause  discoloration  on  weathering;  the  presence  of  much  mica 
may  cause  the  stone  to  scale  off  if  set  on  edge ;  and  clay  may  cause 
injury  to  the  stone  in  freezing  weather  on  account  of  its  capacity 
for  absorbing  moisture.  A  slight  quantity  of  clay,  however,  makes 


PLATE  XIX 


FIG.  1.  —  Marble  quarry,  Pickens  County,  Ga.     (Photo,  loaned  by  S.  W.  McCallie.) 


FIG.  2.  —  Slate  quarry  at  Penrhyn,  Pa.     (H.  Ries,  photo.) 

(157) 


158  ECONOMIC   GEOLOGY 

the  stone  easier  to  dress.  The  value  of  a  sandstone  is  often 
lessened  by  careless  quarrying,  or  by  placing  it  on  edge  in  the 
building,  thus  exposing  the  bedding  planes  to  the  entrance  of  water. 
Varieties  of  Sandstone.  —  With  an  increase  in  the  size  of  their 
grains,  sandstones  pass  into  conglomerates  on  the  one  hand  and 
with  an  increase  in  clay  into  shales.  By  an  increase  in  the  percent- 
age of  carbonate  of  lime  they  may  also  grade  into  limestones. 

On  account  of  these  variations,  as  well  as  the  difference  in  color  and 
the  character  of  the  cement,  a  number  of  varieties  of  sandstone  are  recog- 
nized, of  which  the  following  are  of  economic  value:  arkose,  a  sandstone 
composed  chiefly  of  feldspar  grains;  bluestone,  a  flagstone  much  quarried 
in  New  York;  brownstone,  a  term  formerly  applied  to  sandstones  of  brown 
color,  obtained  from  the  eastern  Triassic  belt,  and  since  stones  of  other 
colors  are  now  found  in  the  same  formation,  the  term  has  come  to  have 
a  geographic  meaning  and  no  longer  refers  to  any  specific  physical  character; 
flagstone,  a  thinly  bedded,  argillaceous  sandstone  used  chiefly  for  paving 
purposes;  freestone,  a  sandstone  which  splits  freely  and  dresses  easily. 

Distribution  of  Sandstones  in  the  United  States.  —  Sandstones 
occur  in  all  formations  from  pre-Cambrian  to  Tertiary.  They  are 
so  widely  distributed  that  for  local  supply  there  are  numerous 
small  quarries  in  many  states,  but  there  are  several  areas  which 
have  been  operated  on  an  extensive  scale,  some  of  them  for  many 
years.  Of  these,  one  of  the  best  known  is  the  Triassic  Brownstone 
belt,  which  extends  from  the  Connecticut  Valley,  in  Massachusetts, 
southwestward  into  North  Carolina. 

This  is  a  red,  brown,  or  even  bluish  sandstone,  of  moderate  hard- 
ness, and  somewhat  variable  texture.  That  from  the  Connecticut 
Valley  district  was  formerly  used  in  enormous  quantities. 

Among  the  Paleozoic  strata  there  are  many  sandstones,  often 
massive,  and  usually  dense  and  hard.  Of  these  the  Medina  and 
Potsdam  are  specially  important  and  much  quarried  in  New  York 
State  (34,  35).  The  same  formations  extend  southward  along  the 
Appalachians  and  are  available  at  several  points.  Devonian  flag- 
stones are  extensively  quarried  at  several  localities  in  New  York 
and  Pennsylvania.  At  the  present  time  the  Lower  Carboniferous 
Berea  sandstone  of  Ohio  (37)  is  in  great  demand  because  of  its  light 
color,  even  texture,  and  the  ease  with  which  it  is  worked.  More- 
over, it  has  the  peculiar  property  of  changing  to  a  uniform  buff  on 
exposure  to  the  air.  There  are  numerous  other  Paleozoic  sand- 
stones in  the  central  states,  among  them  the  Potsdam,  which  covers 
a  wide  area  in  Michigan  and  Wisconsin  (51).  Some  of  this  stone  is 
bright  red  in  color. 


BUILDING  STONES 


159 


The  Mesozoic  and  Tertiary  strata  of  the  West  contain  an  abun- 
dance of  good  sandstone,  and  quarries  opened  in  many  of  them 
yield  a  durable  quality  of  stone.  Though  usually  less  dense  and 
hard  than  the  Paleozoic  sandstones,  they  serve  admirably  for 
buildings  in  the  mild  or  dry  climates  of  the  West. 

Uses  of  Sandstones. — The  wide  distribution  of  sandstones  makes 
them  an  important  source  of  local  structural  material.  They  are 
chiefly  used  for  ordinary  building  work,  and  but  little  for  massive 
masonry  or  monuments.  The  thin-bedded  flagstones  are  much 
used  for  flagging,  and  some  of  the  harder  sandstones  are  split  up  for 
paving  blocks.  For  other  uses,  see  Abrasives. 


QUARRY'FLOOR 


SLATES 

General  Characteristics  (9,  25).  —  Slates  are  metamorphic  rocks 
derived  from  clay  or  shale  or  more  rarely  from  igneous  rocks  (14). 
Their  value  depends  upon  the  presence  of  a  well-defined  plane  of 
splitting,  called  cleavage  (Fig.  57),  developed  by  metamorphism 

through  the  rearrangement 
and  flattening  of  the  original 
mineral  grains  and  the  de- 
velopment of  micaceous 
minerals.  The  cleavage  usu- 
ally develops  at  a  variable 
angle  to  the  bedding  planes 
which  are  often  completely 
obliterated  by  the  meta- 
morphism. When  not  com- 
pletely destroyed,  the  bedding  planes  are  marked  by  parallel  bands, 
called  ribbons,  cutting  across  the  planes  of  cleavage,  but  so  perfect 
is  the  cleavage  in  the  best  slates  that  the  rock  readily  splits  into 
thin  sheets  with  a  smooth  surface. 

Slates  are  commonly  so  fine  grained  that  the  mineral  composition 
is  not  evident  to  the  eye,  but  the  microscope  reveals  the  presence 
of  many  of  the  varied  mineral  grains  found  in  shale,  and  in  addition 
much  chlorite,  developed  by  metamorphism.  Owing  to  the  pres- 
ence of  carbonaceous  particles,  most  slates  are  black  or  bluish  black, 
but  green,  purple,  and  red  slates  are  also  known.  The  specific  grav- 
ity of  slate  is  about  2.7,  and  a  cubic  foot  weighs  between  170  and 
175  pounds. 
Most  slates  are  fairly  durable,  though  the  presence  of  pyrite 


FIG.  57. —  Section  showing  cleavage  and 
bedding  in  slate.  (After  Dale,  U.  S. 
Geol.  Surv.,  19th  Ann.  Kept.,  III.) 


160 


ECONOMIC   GEOLOGY 


along  the  ribbons  may  lead  to  their  decay.     Lime  carbonate  if 

present  in  any  quantity  is  injurious,  and  if  the  slate  is  to  be  used 

for  switchboards,  it  should  be  as  free 

from    magnetite     grains     as     possible. 

Some  colored  slates  fade  on  exposure  to 

the  weather,  but  this  change,  which  is 

due  to  the  bleaching  of  certain  mineral 

grains,  does  not  necessarily  result  in  loss 

of  strength  or  disintegration. 


FIG.  58. —  Section  in  slate 
quarry  with  cleavage  paral- 
lel to  bedding,  a,  purple 
slate;  6,  unworked;  c  and  d, 
variegated;  e  and/,  green;  g 
and  h,  gray-green;  i,  quartz- 
ite;  j,  gray  with  black 
patches.  (After  Dale.) 


In  slate  quarrying  it  is  of  importance  to 
distinguish  between  bedding  and  cleavage. 
The  following  criteria  may  be  used  (43a). 
Quartzite  and  limestone  bands  of  some  per- 
sistence indicate  bedding,  but  care  must  be 
taken  not  to  mistake  vein  quartz  for  quartz- 
ite.  Fossil  impressions  are  always  on  the 
bed  surface.  A  microscopic  section,  trans- 
verse to  cleavage,  may  be  used,  if  other 
means  fail,  to  indicate  divergence  between 
bedding  and  cleavage,  although  in  some  places  the  two  may  agree. 

Special  tests  are  necessary  for  determining  the  quality  of  slate.  They 
include  the  determination  of  its  sonorousness,  cleavability,  abrasive  resist- 
ance, absorption,  elasticity,  and  presence  of  injurious  minerals.C»  The  chemi- 
cal analysis  is  of  limited  value,  but  Merriman  concludes  that  the  strongest 
slate  runs  highest  in  silica  and  alumina  but  not  necessarily  lowest  in  lime 
and  magnesium  carbonates. 

Dale  divides  slates  into  the  following  groups : 

I.  Aqueous  sedimentary. 

A.  Clay  slates:  cemented  by  clay,  lime  carbonate,  or  magnesium 

carbonate.     Fissility,  strength,  and  elasticity  low. 

B.  Mica  slates:  1.  fading;  with  sufficient  iron  carbonate  to  dis- 

color on  exposure.  2.  Unfading;  without  sufficient  iron 
carbonate  to  produce  any  but  very  slight  discoloration  on 
prolonged  exposure. 

Under  each  group  we  may  have  the  following  types:  Graphitic 
(gray-black);  chloritic  (greenish);  hematitic  and  chloritic  (pur- 
plish). The  second  group  may  also  include  hematitic  (reddish). 

II.  Igneous. 

A.  Ash  slates. 

B.  Dike  slates. 

Distribution  of  Slates  in  the  United  States  (Fig.  59).  —  Since 
slates  are  of  metamorphic  origin,  they  are  limited  to  those  regions 
in  which  the  rocks  are  metamorphosed,  and  at  present  the  greater 
part  of  our  supply  comes  from  the  Cambrian  and  Silurian  strata  of 
the  eastern  crystalline  belt  of  the  Atlantic  states. 


162  ECONOMIC  GEOLOGY 

A  series  of  quarries  producing,  red,  green,  purple,  and  variegated 
slates  are  located  in  a  belt  of  Cambrian  and  Hudson  River 
strata  along  the  border  of  New  York  (33)  (PL  XX)  and  Vermont 
(33,  45). 

Black  slates  are  quarried  in  Maine  (3),  New  Jersey  (32), 
Pennsylvania  (3),  (PL  XIX,  Fig.  2),  Maryland  (26),  Georgia  (3), 
and  Virginia  (46).  Other  producing  states  are  Minnesota,  Cali- 
fornia (14,  43a),  and  Arkansas  (12). 

Uses  of  Slate.  —  Slate  is  best  known  as  a  roofing  material, 
but  it  is  also  used  for  mantels,  billiard-table  tops,  floor  tiles, 
steps,  flagging,  slate  pencils,  acid  towers,  washtubs,  etc.  The 
process  of  marbleizing  slates  for  mantles  and  fireplaces  was 
formerly  carried  on  at  several  localities. 

In  quarrying  slate  there  is  from  60  to  80  per  cent  waste,  which 
is  greater  than  in  any  other  building  stone;  but  the  introduction 
of  channeling  machines  in  quarrying  has  done  much  to  reduce 
this.  The  discovery  of  a  use  for  this  waste  has  been  an  im- 
portant problem,  which  has  thus  far  been  only  partially  solved. 
It  is  sometimes  ground  for  paint,  and  attempts  have  been  made 
to  utilize  it  in  the  manufacture  of  bricks  and  Portland  cement. 

Building  Stones  in  Canada  (52a) .  —  The  Canadian  building 
stones  are  developed  chiefly  in  the  eastern  provinces,  including 
Ontario,  and  in  the  far  West,  as  along  the  Pacific  Coast. 

Igneous  Rock  (52a) .  —  Nova  Scotia  and  New  Brunswick 
contain  a  number  of  granite  areas,  yielding  stone  of  varying 
texture  and  color,  the  red  variety  quarried  near  St.  George,  N.  B., 
being  well  known.  There  is  also  considerable  local  development 
around  Halifax.  Nova  Scotia  has  much  fine-grained,  dense 
volcanic  rock,  susceptible  of  decorative  use.  Some  diorite  and 
diabase  for  monumental  work  is  also  quarried  in  New  Bruns- 
wick. 

In  Quebec  granites  and  gneisses  are  worked  at  scattered 
points  in  the  northern  area,  but  the  gray  granite  of  the  Stan- 
stead  district  in  the  eastern  townships  is  the  best  known,  while 
so-called  black  granite  (essexite)  for  monumental  purposes  is 
quarried  in  the  Monteregian  Hills. 

Ontario  granites  and  gneisses  though  abundant  are  little 
developed. 

Not  a  little  granite  is  quarried  along  the  Pacific  Coast  north 
of  Vancouver,  and  the  andesite  from  Vancouver  Island  is  quite 
extensively  used. 


PLATE  XX.  —  View  of  green-slate  quarry,  Pawlet,  Vt.     (Photo,  by  H.  Ries.) 

(163) 


164  ECONOMIC  GEOLOGY 

Limestones.  —  Limestones  of  Paleozoic  age  are  extensively 
quarried  in  Quebec,  notably  around  Montreal  and  Hull,  and 
at  many  points  in  southern  Ontario.  West  of  Winnipeg  a  peculiar 
mottled  limestone  is  quarried,  and  much  used  in  Manitoba. 

Sandstones. — The  Carboniferous  sandstones  of  New  Brunswick 
and  Nova  Scotia,  and  the  Ordovician  and  Silurian  sandstones  of 
Quebec  and  Ontario  have  been  developed  at  many  points.  Oc- 
sionally  sandstone  deposits  are  worked  in  the  Cretaceous  and 
Tertiary  beds  of  the  Western  Provinces,  and  also  on  Vancouver 
Island. 

Marble.  —  Highly  decorative  marbles  of  pre-Cambrian  age 
are  quarried  at  South  Stukely,  Quebec.  Paleozoic  ones  of  gray 
and  green  color,  with  veins  and  cloudings,  are  obtained  near 
Phillipsburg  in  the  same  province.  Crystalline  limestones  are 
abundant  in  Ontario,  but  the  best  known  variegated  marble  is 
that  quarried  near  Bancroft.  A  gray  and  white  marble  is  obtained 
in  the  Kootenay  district  of  British  Columbia. 

Slate.  —  Little  good  slate  is  obtained  in  the  Dominion,  this 
coming  from  the  eastern  townships  of  Quebec. 

Other  Foreign  Building  Stones.  —  Granites  are  quarried  at  a  number 
of  localities  in  Europe,  but  these  exported  to  the  United  States,  and  used 
more  or  less  for  monumental  purposes,  come  chiefly  from  Scotland  and 
Sweden. 

Of  the  many  foreign  sandstones  quarried,  the  bright-red  Scotch  ones  have 
been  used  in  some  quantity  in  the  United  States. 

Volcanic  tuffs  are  widely  distributed  and  abundantly  used  in  central 
Mexico,  and  these,  together  \\ith  lava  rock,  have  been  frequently  quarried 
in  Italy,  the  Auvergne  region  of  France,  and  even  other  localities. 

The  roofing  slates  found  in  the  Cambrian  and  Crodvician  of  North  Wales 
are  among  the  best  k noun  deposits  of  the  v.orld. 

Many  lin  estones  are  quarried,  especially  in  the  post-Carboniferous  forma- 
tions. Among  these  if  ay  be  mentioned  the  Portland  stone  of  the  Jurassic 
on  the  Isle  of  Portland,  near  Weymouth,  and  the  soft  French  limestones, 
of  which  the  Caen  stone,  often  used  in  America  for  interior  work,  are  well 
known.  Another  soft,  but  dense  limestone,  capable  of  taking  a  polish, 
and  frequently  employed  here,  is  that  of  Hauteville,  France. 

Marbles  of  great  beauty  are  quarried  in  many  foreign  countries,  and 
widely  exported.  Among  the  best  known  are:  White  statuary  marble 
from  Carrara,  Italy;  yellow,  black-veined  Sienna,  and  whitish,  veined 
Pavonazzo,  from  the  same  country;  Skyros  breccia  from  Greece;  Griotte 
or  red  from  France;  Parian  white  from  Greece;  banded  Cippolino  from 
Switzerland,  and  a  host  of  others.  Many  of  them  are  of  highly  decorative 
character,  but  of  low  weather-resisting  qualities. 

The  same  is  true  of  the  beautiful  serpentine  marbles,  which  may  be  ob- 
tained from  Ireland,  Italy,  and  Greece. 


BUILDING   STONES 


165 


Production  of  Building  Stones.  —  The  production  of  building 
stones  by  kinds  for  the  last  5  years  was  as  follows: — 

PRODUCTION  OF  BUILDING  STONES  IN  THE  UNITED  STATES  FROM  1910  TO  1914 


ft 
KIND. 

1910 

1911 

1912 

IS  13 

1914 

Granite     . 
Trap  rock 
Sandstone  * 
Marble      . 
Limestone 
Slate    .      . 

$20,541,967 
6,452,141 
7,930,019 
6,992,779 
34,603,678 
6,236,759 

$21,194,228 
6,739,141 
7,730,868 
7,546,718 
33,897,612 
5,728,019 

$19,223,302 
7,560,049 
6,893,611 
7,786,458 
36,729,800 
6,043,318 

$20,733,217 
9,134,494 
7,248,965 
7,870,890 
38,745,429 
6,175,476 

$20,028,919 
7,865,998 
7,501,808 
8,121,412 
33,894,155 
5,706,787 

Total    .     .     . 

$82,757,343 

$82,836,586 

$84,236,538 

$89,908,471 

$83,119,079 

1  Includes  bluestone. 

It  should  be  noted  that  the  stone  statistics  compiled  by  the 
United  States  Geological  Survey  include  not  only  building  stone, 
but  stone  used  for  monuments,  road  material,  etc.  Some  idea 
of  the  quantity  used  for  each  of  these  purposes  can  be  gained 
from  the  following  table: 


VALUE  OF  STONE  USED  FOR  DIFFERENT  PURPOSES  IN  1914 


MONU- 

KINDS. 

BUILDING 
(Rouen  AND 
DRESSED). 

MENTAL 
(ROUGH 

AND 

FLAG- 
STONE. 

CURB- 
STONE. 

PAVING 
STONE. 

CRUSHED 
STONE. 

DRESSED). 

Granite     . 

$6,481,091 

$4,744,088 

$   13,849 

$760,952 

$2,831,568 

$  3,975,575 

Trap  rock 

45,134 







112,246 

6,225,805 

Sandstone 

1,825,179 

—  ,  — 

519,957 

988,317 

713,692 

1,898,505 

Limestone 

3,896,854 



7,134 

120,407 

114,877 

18,061,881 

Marble  1  . 

5,548,294 

2,303,484 









Total    .     .     . 

$17,796,552 

$7,047,572 

$540,940 

$1,869,676 

$3,772,383 

$30,161,766 

1  Marble  for  both  exterior  and  interior  building. 

The  value  of  the  building  stones  produced  by  the  several  more 
important  states,  together  with  the  kind  of  stone  produced 
chiefly  in  1914,  is  given  below: — 

PRODUCTION  OF  BUILDING  STONES  IN  CANADA  1911  TO  1914 


KIND. 

1911 

1912 

1913 

1914 

Granite     .     .     .     .... 
Limestone     .... 
Marble      
Sandstone     .... 

1,119,865 

1,373,119 
2,762,936 
260,764 
329,352 

1,653,791 
3,204,091 
249,975 
396,782 

$2,179,930 
2,730,430 
192,533 
490,584 

162,783 

166 


ECONOMIC   GEOLOGY 


PRODUCTION  OF  BUILDING  STONES  IN  MORE  IMPORTANT   STATES  IN  1914 


STATE. 


Pennsylvania. 
Vermont    . 
New  York      . 
Ohio      .     .     . 
California  . 
Indiana 
Massachusetts 
Illinois  . 
Wisconsin 
Missouri    . 
Georgia 
Virginia 
Tennessee 
Maine   . 
Washington    . 


TOTAL  VALUE. 


$8,153,413 
6,635,477 
6,575,079 
5,655,713 
4,610,781 
4,136,132 
3,438,556 
2,934,078 
2,413,435 
2,294,103 
2,238,789 
2,152,378 
1,932,462 
1,723,032 
1,600,615 


PER     CENT     OF 

TOTAL,  U.  S. 
PRODUCTION. 


10.53 
8.57 
8.49 
7.13 
5.96 
5.34 
4.44 
3.79 
3.12 
2.96 
2.89 
2.78 
2.50 
2.23 
2.07 


KIND  PRODUCED 
CHIEFLY. 


Limestone 

Marble  and  Granite 

Limestone 

Limestone 

Granite 

Limestone 

Granite 

Limestone 

Granite 

Limestone 

Marble  and  granite 

Limestone 

Marble 

Granite 

Trap 


IMPORTS  OF  STONE  INTO  THE  UNITED  STATES  IN  1913  AND  1914 


KIND. 


1913 


1914 


Marble : 

In  block,  rough,  etc.  . 

Sawed  or  dressed     .  . 

Slabs  or  paving  tiles  . 

All  other  manufactures 
Mosaic  cubes  (loose)    . 

Attached  to  paper  .  . 

Total 

Onyx: 

In  blocks,  rough,  etc.   . 
All  other  manufactures 

Total 

Granite : 

Dressed 

Rough  .     .     ...     . 

Total 

Stone  (other) : 

Dressed 

Rough  

Rough  (other) 

Total  .     .     .     .     . 
Grand  Total 


$1,024,595 

606 

50,788 

242,674 

48,944 


$878,284 


62,828 

153,920 

30,566 

1,541 


$1,367,607 


34,518 
1,803 


$1,127,139 


31,368 
2,026 


$  36,321 


110,451 
5,074 


$  33,394 


155,777 

2,280 


$  115,525 


23,422 

63,260 

9,017 


$158,057 


15,944 
25,978 
28,911 


$95,699 


$70,883 


$l,b!5,152 


$1,389,473 


BUILDING  STONES 


167 


Exports  and  Imports.  • —  The  following  figures  show  the  value 
of  the  exports  for  the  years  1913  and  1914: 

EXPORTS  OF  STONE  FROM  THE  UNITED  STATES  IN  1913  AND  1914 


KIND 

1913 

1914 

Marble  and 
All  othors 

stone,  unmanufactured     .     .     ... 

$    606,745 
1  250  147 

$    559,556 
803  686 

Total 

$1  856  892 

$1  363  242 

The  exports  from  Canada  in  1914  were:  Ornamental  stone, 
231  tons,  valued  at  $5,607;  and  building  stone,  63,009  tons, 
valued  at  $46,198. 


REFERENCES    ON   BUILDING    STONES 

GENERAL  ON  PROPERTIES.  1.  Hirschwald,  Handbuch  der  bautechnischen 
Gesteinspriifung,  Berlin,  1912.  Borntrager  Bros.  2.  Merrill,  Stones 
for  Building  and  Decoration,  3d  ed.,  New  York,  1904.  (Wiley  &  Sons.) 
For  general  information  on  properties  and  testing,  see  also,  3.  Buck- 
ley, Jour.  Geol.,  VIII:  160  and  333,  1900.  4.'  Julien,  Jour.  Frankl. 
Inst,,  CXLVII,  1899.  5.  Merrill,  Maryland  Geol.  Surv.,  II:  47,  1898. 
6.  Watson,  Ga.  Geol.  Surv.,  Bull.  9-A,  1903.  7.  McCourt,  N.  Y.  State, 
Mus.,  Bull.  100,  1906  (Fire  tests,  N.  Y.),  and  N.  J.  Geol.  Surv.,  Ann. 
Rep.  1906:  17,  1907  (Fire  tests,  N.  J.).  8.  Humphreys,  U.  S.  Geol. 
Surv.,  Bull.  370,  1909.  (Fire  tests.)  9.  Ries,  Building  Stones  and 
Clay-products,  New  York,  1912.  10.  Ren  wick,  Marble  and  Marble 
Working,  London,  1909.  GENERAL  REPORTS.  10a.  Dale,  U.  S.  Geol. 
Surv.,  Bull.  586,  1914.  (Slate,  U.  S.)  103.  Watson,  Ibid.,  Bull.  426, 
1910.  (Granites,  southern  states.)  For  maps  showing  distribution  of 
quarries  in  United  States,  see  U.  S.  Geol.  Surv.,  Min.  Res.,  1911,  1912, 
and  1913. 

AREAL  REPORTS.  Alabama:  11.  Smith,  Eng.  and  Min.  Jour.,  LXVI: 
398. —  Alaska:  lla.  Wright,  U.  S.  Geol.  Surv.,  Bull.  345:  116,  1908. 
(General.)— Arkansas:  12.  Purdue,  Ark.  Geol.  Surv.,  1909.  (Slate.) 
13.  Hopkins,  Ark.  Geol.  Surv.,  Ann.  Rept.,  1890,  IV,  1893.  (Marbles.) 
—  California:  14.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  225:  417,  1904. 
(Slate.)  15.  Jackson,  Calif.  State  Min.  Bureau,  8th  Ann.  Rept.,  885, 
1888.  (General.)  16.  Aubury  and  others,  Calif.  State  Min.  Bur., 
Bull.  38,  1906.  (General.)  —  Colorado:  17.  Lakes,  Mines,  and  Min- 
erals, XXII:  29  and  62,  1901.  (General.)  —  18.  Merrill,  Stones  for 
Building  and  Decoration,  New  York,  1904.  —  Connecticut:  18a.  Dale 
and  Gregory,  U.  S.  Geol.  Surv.,  Bull.  484,  1911.  (Granites.)  —  Georgia: 
19.  McCallie,  Ga.  Geol.  Surv.,  Bull.  1,  2d  ed.,  1904.  (Marbles.)  20. 
Watson,  Ibid.,  Bull.  9-A,  1903.  (Granites  and  Gneisses.)  —  Indiana: 
21.  Hopkins,  Ind.  Geol.  and  Nat.  Hist.  Surv.,  20th  Ann.  Rept.:  188, 


168  ECONOMIC   GEOLOGY 

1896.  22.  Siebenthal,  U.  S.   Geol.  Surv.,    19th  Ann.  Kept.,  VI:   292, 
1898.     (Bedford  limestone.)     23.  Thompson,  Ind.  Geol.  and  Nat.  Hist. 
Surv.,  17th  Kept.:  19,  1891.     (General.)  —  Iowa:  23a.  Beyer  and  Will- 
iams, la.   Geol.  Surv.,  XVII:    185,    1907.     (General.)      236.  Marston, 
Ibid.,  541,  1907.      (Tests.) — Kentucky:  23c.  Crump,  Ky.  Geol.  Surv., 
4th    ser.,    I:    1037,    1914.     (Oolitic   limestone.)  —  Maine:    24.  Merrill, 
Stones  for  Building  and  Decoration.     Wiley  &  Sons,  New  York,  1904. 
25.  Dale,    U.    S.    Geol.    Surv.,    Bull.    586,   1914.     (Slate),    25a.  Dale, 
U.    S.    Geol.    Surv.,    Bull.    313,    1907.      (Granite.)  —  Maryland:     26. 
Matthews,    Md.   Geol.    Surv.,    II:     125,    1898.     (General.)  —  Massa- 
chusetts:    27.  Dale,  U.  S.  Geol.  Surv.,  Bull.   313,    1907.     (Granites.) 

28.  Dale,  U.  S.  Geol.  Surv.,  Bull.  354,  1908.     (Granites.)  —  Michigan: 

29.  Benedict,    Stone,    XVII:    153,     1898.     (Bayport    district.)  —  Mis- 
souri:   30.  Buckley   and  Buehler,   Mo.   Bur.  Geol.  and  Mines,  Vol.  II, 
1904. —  Montana:    30a.  Rowe,  Univ.  Mont.,    Bull.  50.     (General.) - 
New    Hampshire:     31.    Dale,    U.    S.    Geol.    Surv.,    Bull.    354,     1908. 
(Granites.)  —  New  Jersey:    32.  Lewis,  N.  J.  Geol.  Surv.,  Ann.  Kept., 
1908:  53,  1909.     (General.) —New  York:   33.  Dale,  U.  S.  Geol.  Surv., 
Bull.  586.     (Slate  belt.)     34.  Dickinson,    N.   Y.    State  Museum,  Bull. 
61,  1903.     (Bluestone  and  other  Devonian  sandstones.)     34o.  Newland, 
N.  Y.  State  Museum,  Bull.  181,  1916.     (General.)     35.    Smock,  N.  Y. 
State  Museum,  Bull.  3,  1888.  —  North  Carolina:    36.  Watson,   Laney, 
and  Merrill,  N.   Ca.    Geol.    Surv.,  Bull.  2,   1906.     (General.)  —  Ohio: 
37.    Orton,     Ohio     Geol.     Surv.,     V:      578,     1884.      (General.)      37a. 
Orton    and   Peppel,    Ibid.,    4th   ser.,    Bull.    4,    1906.     (Limestones.)  — 
Oklahoma:   38.  Gould,  Okla.  Geol.  Surv.,  Bull.   1:46,  1908,  also  Bull. 
5:    31,   1911.       Oregon:    38a.  Darton,  U.  S.  Geol.,  Surv.  Bull.  387, 
1909.     (Limestones.)     386.    Parks,    Min.    Res.     Ore.,     I:     10,    1914. 
Pennsylvania:    39.  Hopkins,  Penn.  State  College,  Ann.  Rept.,   1895; 
Appendix,  1897;    also  U.  S.  Geol.  Surv.,  18th  Ann.  Rept.,  V:    1025, 

1897.  (Brownstones.)     40.  Lesley,    Tenth    Census,    U.    S.,    X:     146, 
1884.     (General.)     40a.  Hice,  Top.  and  Geol.  Com.  Pa.,  Bull.  9:    98, 
1913.     (Marbles.)  —Rhode  Island:    41.  Dale,  U.  S.  Geol.  Surv.,  Bull. 
354,    1908.     (Granites.)  —  South   Carolina:    4 lo.  Sloan,   S.   Ca.   Geol. 
Surv.,   ser.   IV,   Bull.   2:     162,    19C8.  —  South  Dakota:    42.  Todd,   S. 
Dak.   Geol.   Surv.,   Bull.   3:    81,    1902.     (General.) —  Tennessee:    43. 
Gordon,  Tenn.  Geol.  Surv.,  Bull.  2,  1911.     (Marbles.)     See  also  Ref.  2. 
—  Texas:    43a.  Burchard,   U.  S.   Geol.  Surv.,  Bull.  430.  —  Vermont : 
44.  Perkins,   Rept.  of  State  Geologist  on  Mineral  Industries  of  Vt., 
1899-1900,   1900,   1903-1904,   1907-1908;    and  45.  Report  on  Marble, 
Slate,   and  Granite  Industries,    1898.     45a.  Dale,   U.   S.   Geol.   Surv., 
Bull.   521,  1912,  and   589,  1915.     (Marbles.) —Virginia:    46.  Watson, 
Mineral  Resources  of  Va.,  Lynchburg,    1907.      47.  Dale,   U.  S.  Geol. 
Surv.,  Bull.  586,  1914.    (Slate.)  —  Washington:  48.  Shedd,  Wash.  Geol. 
Surv.,  II:     3,    1902.     (General.)  —  West   Virginia:     49.  Grimsley,    W. 
Va.  Geol.  Surv.,    Ill,   1905.     (Limestones.)     50.    Ibid.,  IV:  355,  1909. 
(Sandstones.)  — Wisconsin:    51.    Buckley,    Wis.  Geol.  and  Nat.  Hist. 
Surv.,     Bull.     IV,    1898.      (General.) —Wyoming:      52.  Knight,    Eng. 
and  Min.  Jour.,  LXVI:  546,  1898. 


BUILDING  STONES  169 

Canada:  52a.  Parks,  Can.  Mines  Branch,  Reports  on  Canadian  Building 
Stones:  I,  1912  (Ont.),  II,  1914  (Maritime  Provinces),  III,  1914  (Quebec). 

REFERENCES    ON    ONYX    MARBLE 

53.  De'Kalb,  "Onyx  Marbles,"  Trans.,  Am.  Inst.  Min.  Engrs.,  XXV: 
557,  1896.  54.  Merrill,  Stones  for  Building  and  Decoration  (New 
York),  3d  ed.,  1904.  55.  Merrill,  Ann.  Kept.  U.  S.  Nat.  Mus.  (Wash- 
ington), 1895.  56.  Merrill,  Min.  Indus.,  Vol.  II,  "Onyx/'  1894.  56a. 
kawton,  Min.  and  Sci.  Press,  C :  791,  1910. 


CHAPTER  IV 
CLAY 

Definition.  —  Clay  may  be  defined  as  an  earthy  substance  of 
fine  texture  containing  a  mixture  of  hydrous  aluminum  silicates, 
with  fragments  of  other  minerals,  such  as  silicates,  oxides,  car- 
bonates, etc.,  and  colloidal  material  which  may  be  of  either 
organic  or  mineral  character.  The  mass  possesses  plasticity 
(usually)  when  wet,  and  becomes  rock-hard  when  fired  to  at 
least  a  temperature  of  redness. 

Two  important  classes  of  clays  are  the  residual  and  the  trans- 
ported ones. 

Residual  Clays  (8).  —  Clays  are  derived  primarily  and  prin- 
cipally from  the  decomposition  of  crystalline  rocks,  more  espe- 
cially feldspathic  va- 
rieties, and  deposits 
thus  formed  will  be 
found  overlying  the 
parent  rock  and  often 
grading  down  on  to 
it.  From  its  method 
of  origin  and  position 
it  is  termed  a  residual 

FIG.  60.  —  Section  showing  formation  of  residual  clay,    clay  (Fig.  60) . 

(After  Ries,  U.  S.  GeoL  Surv.,  Prof.  Pap.  11.)  A11  residual  clays  prob- 

ably contain    a    variable 

amount  of  kaolinite  (8)  or  clay  substance.  This  mineral,  which  is  white  in 
color,  results  from  the  decomposition  of  feldspar,  either  by  weathering,  or, 
less  often,  by  the  action  of  volcanic  vapors.  The  decay  of  a  large  mass  of 
pure  feldspar  would  therefore  yield  a  mass  of  white  clay,  but,  in  most  instances, 
the  feldspar  is  associated  with  other  minerals,  such  as  quartz,  mica,  and 
hornblende,  all  of  which,  except  the  quartz,  and  muscovite,  decay  with 
greater  or  less  rapidity,  and  some  of  these,  such  as  the  hornblende,  may 
likewise  yield  a  hydrous  aluminum  silicate.  Any  ferruginous  minerals  in 
the  rock  will,  in  decomposing,  yield  limonite,  which  stains  the  mass. 

Large  masses  of  pure  feldspar  are  rare,  but  feldspathic  rocks,  such 
as  granite  or  syenite,  are  more  common,  and  these  will  also  decompose 
to  clay;  but,  since  the  parent  rock  contains  other  minerals,  such  as  quartz 
or  mica,  these  will  either  remain  as  sand  grains  in  the  clay,  or,  by  decom« 

170 


CLAY 


171 


position,  will  form  soluble  compounds,  or  iron  stains.  Sedimentary  rocks 
as  well  as  crystalline  ones  may  produce  residual  clay.  That  derived  from 
limestone  is  the  insoluble  clayey  impurities  left  after  the  carbonates  are 
dissolved. 

The  extent  of  a  deposit  of  residual  clay  will  depend  on  the  extent  of  the 
parent  rock  and  the  topography  of  the  land,  which  also  influences  its  thick- 
ness. On  steep  slopes  much  of  the  clay  may  be  washed  away;  and  residual 
clays  are  also  rare  in  glaciated  regions,  for  the  reason  that  they  have  been 
swept  away  by  the  ice  erosion.  They  are  consequently  wanting  in  most 
of  the  Northern  states,  but  abundant  in  many  parts  of  the  Southern  states, 
where  the  older  formations  appear  at  the  surface. 

Transported  Clays  (8).  —  With  the  erosion  of  the  land  surface 
the  particles  of  residual  clay  become  swept  away  to  lakes,  seas,  or 
the  ocean,  where  they 
settle  down  in  the 
quiet  water  as  a  fine 
aluminous  sediment, 
forming  a  deposit  of 
sedimentary  clay  (Fig. 
61).  Such  beds  are 
often  of  great  thick- 


LOAMY  CLAY7 

CLAY 

SAND 

SAND  AND  GRAVEL 


FIG.  61.  —  Section  of  a  sedimentary  clay  deposit. 
(After  Ries,  U.  S.  Geol.  Surv.,  Prof.  Pap.  11.) 


ness  and  vast  extent. 
With  the  accumula- 
tion of  many  feet  of  other  sediments  on  top  of  them,  they  become 
consolidated  either  by  pressure  or  by  the  deposit  of  a  cement  around 
the  grains.  Consolidated  clay  is  termed  shale,  and  this  upon 
being  ground  and  mixed  with  water  often  becomes  as  plastic  as  an 
unconsolidated  clay. 

Residual  materials  may  also  have  been  transported  by  wind  or 
glacial  action,  to  form  clayey  deposits. 

The  following  are  important  types  of  transported  clays :  — 

Marine  Clays.  —  Formed  by  the  deposition  on  the  ocean  floor  of  the 
finer  particles  derived  from  the  waste  of  the  land.  Such  ancient  sea- 
bottom  clays  have  been  elevated  to  form  dry  land  in  all  the  continents,  in 
many  cases  forming  consolidated  clay  strata,  but  elsewhere,  especially  in 
coastal  plains,  in  unconsolidated  condition.  Extensive  clay  deposits  are 
also  formed  in  protected  estuaries  and  lagoons  along  the  seacoast. 

Flood-plain  Clays.  —  Formed  by  the  deposition  of  clayey  sediment  on 
the  lowlands  bordering  a  river  during  periods  of  flood.  Layer  upon  layer, 
this  deposit  builds  a  flood  plain  often  of  great  extent  and  depth.  Such 
areas  of  flood-plain  clays  are  most  extensive  along  the  greater  rivers  and 
in  the  deltas  which  they  have  built  in  the  sea. 

Lake  Clays.  —  Clay  is  deposited  on  the  bottom  of  many  lakes  and 
ponds  in  the  same  manner  as  on  the  ocean  bottom.  Where  the  streams 


172  ECONOMIC  GEOLOGY 

bring  only  fine  particles  the  filling  of  a  lake  may  be  entirely  of  clay.  Many 
lakes  have  been  either  drained  or  completely  filled  and  their  clays  there- 
fore made  available.  This  is  especially  true  of  small,  shallow  lakes  formed 
during  the  Glacial  Period. 

Glacial  Clays,  commonly  known  as  till  or  bowlder  clay,  a  rock  flour 
ground  in  the  glacial  mill  in  which  rock  fragments  were  worn  down  to 
clay  by  being  rubbed  together  or  against  the  bed  rock  over  which  the 
ice  moved.  When  the  ice  melted,  this  deposit  was  left  in  a  sheet  of  varying 
thickness  and  characteristics  over  a  large  part  of  the  area  which  the  ice 
covered.  It  is  not  always,  strictly  speaking,  a  sedimentary  deposit. 

JEolian  Clays.  —  Wind  drifts  dry  clay  about,  and  in  favorable  posi- 
tions causes  its  accumulation  in  beds.  This  is  true  of  the  Chinese  loess, 
a  wind-blown  deposit  derived  from  residual  soils  and  drifted  about  in 
the  arid  climate  of  interior  China.  Some  at  least  of  the  loess  clays  of  the 
Mississippi  Valley  seem  to  have  a  similar  origin,  the  source  of  the  clay  being 
glacial  deposits;  in  other  cases  loess  seems  to  be  a  water  deposit  either  in 
shallow  lakes  or  else  in  broad,  slowly  moving  streams. 

Properties  of  Clay.  —  These  are  of  two  kinds,  physical  and  chemi- 
cal, and  since  they  exercise  an  important  influence  on  the  behavior 
of  the  clay,  the  most  important  ones  may  be  described. 

Physical  Properties  (8,  1).  —  These  include  plasticity,  tensile 
strength,  air  and  fire  shrinkage,  fusibility,  and  specific  gravity. 

Plasticity  may  be  defined  as  the  property  which  clay  possesses  of  forming 
a  plastic  mass  when  mixed  with  water,  thus  permitting  it  to  be  molded  into 
any  desired  shape,  which  it  retains  when  dry.  This  is  an  exceedingly  im- 
portant character  of  clay.  Clays  vary  from  exceedingly  plastic,  or  "fat" 
ones,  to  those  of  low  plasticity  which  are  "lean"  and  sandy.  Plasticity 
is  probably  due  in  part  to  fineness  of  grain,  and  in  part  to  the  presence  of 
colloids  (1,  6a,  8). 

Tensile  strength  is  the  resistance  which  a  mass  of  air-dried  clay  offers 
to  rupture,  and  is  probably  due  to  interlocking  of  the  particles  and  set 
colloids.  Tests  show  that  the  tensile  strength  of  clays  varies  from  15  to 
20  pounds  per  square  inch  up  to  400  pounds  or  more  per  square  inch.  Many 
common  brick  clays  range  from  100  to  200  pounds. 

Shrinkage  is  of  two  kinds  —  air  shrinkage  and  fire  shrinkage.  The  for- 
mer takes  place  while  the  clay  is  drying  after  being  molded,  and  is  due  to  the 
evaporation  of  the  water,  and  the  drawing  together  of  the  clay  particles. 
The  latter  occurs  during  firing,  and  is  due  to  a  compacting  of  the  mass  as 
the  particles  soften  under  heat.  Both  are  variable.  In  the  manufacture 
of  most  clay  products  an  average  total  shrinkage  of  about  8  or  9  per  cent 
is  commonly  desired.  Excessive  air  or  fire  shrinkage  causes  cracking  or 
warping  of  the  clay.  To  prevent  this  a  mixture  of  clays  is  often  used. 

Fusibility  is  one  of  the  most  important  properties  of  clays.  When 
subjected  to  a  rising  temperature,  clays,  unlike  metals,  soften  slowly,  and 
hence  fusion  takes  place  gradually.  In  fusing,  the  clay  passes  through 
three  stages,  termed,  respectively,  incipient  fusion,  vitrification,  and 
viscosity. 


CLAY  173 

In  the  lower  grades  of  clay,  that  is,  those  having  a  high  percentage  of 
fluxing  impurities,  incipient  fusion  may  occur  at  about  1000°  C.,  while  in 
refractory  clays,  which  are  low  in  fluxing  impurities,  it  may  not  occur  until 
1300°  or  1400°  C.  is  reached.  The  temperature  interval  between  incipient 
fusion  and  vitrification  may  be  as  low  as  30°  C.  in  calcareous  clays,  or  as. 
much  as  200°  C.  in  some  others.  The  recognition  of  this  variation  is  of 
considerable  practical  importance,  and  vitrified  products,  such  as  paving 
bricks  and  stoneware,  have  to  be  made  from  a  clay  in  which  the  three  stages 
of  fusion  are  separated  by  a  distinct  temperature  interval.  The  importance 
of  this  rests  on  the  fact  that  it  is  impossible  to  control  the  temperature  of  a, 
large  kiln  within  a  few  degrees,  and  there  must  be  no  danger  of  running 
into  a  condition  of  viscosity  in  case  the  clay  is  heated  beyond  its  point  of 
vitrification. 

Specific  gravity  varies  commonly  from  about  1.70  to  2.30. 

Chemical  Properties  (8) .  —  The  number  of  common  elements 
which  have  been  found  in  clays  is  great,  and  even  some  of  the  rarer 
ones  have  been  noted;  but  in  a  given  clay  the  number  of  elements 
present  is  usually  small,  being  commonly  confined  to  those  deter- 
mined in  the  ordinary  chemical  analyses,  which  show  their  existence 
in  the  clay,  but  not  always  the  state  of  the  chemical  combination. 
The  common  constituents  of  a  clay  are  silica,  alumina,  ferric  or 
ferrous  oxide,  lime,  magnesia,  alkalies,  titanic  acid,  and  combined 
water.  Organic  matter,  and  sulphur  trioxide,  though  often  pres- 
ent, are  usually  in  small  amounts.  Carbon  dioxide  is  always  found 
in  calcareous  clays.  The  effect  of  these  may  be  noted  briefly. 

Silica  if  present  in  the  form  of  quartz  or  other  crystalline  grains,  aids  in 
lowering  the  plasticity  and  shrinkage  at  low  temperatures.  Silica  in  colloidal 
form  probably  increases  the  plasticity  (6a).  Alumina,  which  is  most  abun- 
dant in  white  clays,  is  a  refractory  ingredient.  Iron  oxide  acts  as  a  coloring 
agent  in  both  the  raw  and  burned  clay,  small  quantities  usually  coloring 
a  burned  clay  buff,  and  larger  amounts  (4  to  7  per  cent),  if  evenly  distributed, 
turning  it  red.  It  also  acts  as  a  flux  in  burning.  Whatever  the  iron  compound 
present  in  the  raw  clay  it  changes  to  the  oxide  in  burning.  Lime,  magnesia, 
and  alkalies  are  also  fluxing  ingredients  of  the  clay.  The  combined  per- 
centage of  fluxing  impurities  is  small  in  a  refractory  clay,  and  often  high 
in  a  low-grade  one.  Lime,  if  present  in  considerable  excess  over  the  iron, 
will,  in  burning,  exert  a  bleaching  effect  on  the  latter.  For  this  reason, 
highly  calcareous  clays,  such  as  those  in  the  Great  Lake  region,  burn  cream 
or  buff.  When  lime  is  present  in  large  amounts,  it  also  causes  clay  to  soften 
more  rapidly  in  firing  than  it  otherwise  would. 

Chemically  combined  water  passes  off  chiefly  between  450°  and  650°  C., 
and  carbonaceous  matter  mostly  between  800°  and  900°  C.  This  loss 
leaves  the  clay  temporarily  porous  until  fire  shrinkage  sets  in.  Titanic  acid, 
though  rarely  exceeding  1  per  cent,  acts  as  a  flux  at  high  temperatures  at 


174  ECONOMIC   GEOLOGY 

least.     Sulphur  trioxide  is  rarely  present  in  sufficiently  high  amounts  to  in- 
terfere with  the  successful  burning  of  the  clay. 

Carbon  colors  a  raw  clay  gray  or  black,  and  several  per  cent  may  give 
much  trouble  in  burning,  unless  driven  out  of  the  clay  before  it  becomes 
dense. 

Chemical  Composition.  —  As  might  be  expected  from  their  diverse 
modes  of  origin,  clays  vary  widely  in  their  chemical  composition. 
There  is  every  gradation  from  those  which,  in  composition,  closely 
resemble  the  mineral  kaolinite,  to  those,  like  ordinary  brick  clays, 
in  which  there  is  a  high  percentage  of  impurities.  This  variation 
is  shown  in  the  opposite  table. 

The  absence  of  ferrous  oxide,  titanic  oxide,  sulphur  trioxide,  organic 
matter,  and  manganous  oxide  in  many  of  the  analyses  (p.  175)  does 
not  necessarily  indicate  their  non-existence  in  these  clays.  Probably  all 
contain  at  least  small  percentages  of  these  substances,  but  they  are  rarely 
determined. 

Classification  of  Clay.  —  It  is  possible  to  base  a  classification  of  clays 
either  on  origin,  chemical  and  physical  properties,  or  uses.  But  since  the 
subdivisions  which  can  be  made  are  not  sufficiently  distinct,  each  of  these 
gives  rise  to  a  more  or  less  unsatisfactory  grouping.  The  following  classi- 
fication is  based  partly  on  mode  of  origin  and  partly  on  physical  char- 
acters (8) :  — 

A.  Residual  clays.     (By  decomposition  of  rocks  in  situ.} 

I.  Kaolins  or  china  clays  (white-burning). 

(a)  Veins,  derived  from  pegmatite,  rhyolite,  etc. 

(6)  Blanket  deposits,  from  areas  of  igneous  or  metamorphic  rocks. 

(c)  Pockets  in  limestone,  as  indianaite  (24).     (Origin  doubtful.) 

(d)  Bedded  deposits  from  feldspathic  sandstones. 

II.  Red-burning  residuals,  derived  from  different  kinds  of  rocks. 

B.  Colluvial  clays,  representing  deposits  formed  by  wash  from  the  fore- 

going, and  of  either  refractory  or  non-refractory  character. 

C.  Transported  clays. 

I.  Deposited  in  water. 

(a)  Marine  clays  or  shales.     Deposits  often  of  great  extent. 
White-burning  clays.     Ball  clays  and  plastic  kaolins. 
Fire  clays  or  shales.     Buff-burning. 

Impure  clays  or  shales.  1  Calcareous. 

(  Non-calcareous. 

(6)  Lacustrine  clays  (deposited  in  lakes  or  swamps). 
Fire  clays  or  shales. 
Impure  clays  or  shales,  red-burning. 
Calcareous  clays,  usually  of  surface  character. 

(c)  Flood-plain  clays.     Usually  impure  and  sandy. 

(d)  Estuarine  clays  (deposited  in  estuaries).  Mostly  impure  and 

finely  laminated. 


CLAY 


175 


ANALYSES  SHOWING  VARIATION  IN  COMPOSITION  OF  CLAYS 


I 

II 

in 

IV 

V 

Silica  (SiO-0 

463 

45  78 

57  62 

P;Q  GO 

AC  AO 

Alumina  (Al->Os)                     .     . 

398 

3646 

2400 

27  56 

14  98 

Ferric  oxide  (FeaOa)     .... 
Ferrous  oxide  (FeO)     .     .     .     . 
Lime  (CaO)                                 . 

.28 
1.08 
50 

1.9 
1.2 

7 

1.03 
tr 

4.16 

1  48 

Magnesia  (MgO) 

.04 

.3 

tr 

1  09 

Potash  (K°O) 

1 

f       5 

1               .CF 

1 

Soda  (Na-'O)    

.25 

.2 

.64 

3.36 

Titanic  oxide  (TiO2)    .     . 
Water  (H2O)       .     .     .     .     .    , 

Moisture 

13.9 

13.40 
2.05 

10.5 

2.7 

9.70 
1.12 

3.55 

2.78 

Carbon  dioxide  (CO2)  .     .     .  "  • 
Sulphur  trioxide  (SO3)     ... 
Organic  matter                           . 

— 

.35 

Manganous  oxide  (MnO)     .    . 

— 

— 

— 

— 

.64 

Total  ....              ... 

10000 

9984 

9997 

99.97 

100.66 

VI 

VII 

VIII 

IX 

X 

Silica  (SiO2)    

82.45 

54.64 

38.07 

90.00 

47.92 

Alumina  (AkOa)      .     .     .     .     ; 
Ferric  oxide  (Fe2O3)     ...     * 
Ferrous  oxide  (FeO)    .     .... 
Lime  (CaO)    

10.92 
1.08 

.22 

14.62 
5.69 

5.16 

9.46 
2.70 

15.84 

4.60 
1.44 

.10 

14.40 
3.60 

12.30 

Magnesia  (MgO) 

96 

2  90 

850 

.10 

1.08 

Potash  (K*O)      

f    tr. 

1.20 

Soda  (Na2O)  
Titanic  oxide  (TiO2)   .     .     .    . 
Water  (H*O)  

1.00 
2.4 

5.89 
3.741 

2.76 

t    tr. 
.70 
[    3.04 

1.50 
1.22 

4.85 

Moisture    .... 

1 
.85 

2.49 

- 

Carbon  dioxide  (CO2)      .     .     . 
Sulphur  trioxide  (SOs)     .     .     . 
Organic  matter  . 

— 

4.80 

20.46 

9.50 
1.44 
1.34 

Manganous  oxide  (MnO)     .     ... 

— 

.76 

— 

— 

Total  .     .    -. 

9903 

99.05 

100.28 

99.98 

100.35 

I.  Kaolinite. 
II.  Washed  kaolin,  Webster,  N.  Ca. 

III.  Plastic  fire  clay,  St.  Louis.  Mo. 

IV.  Flint  fire  clay,  Salineville,  O. 
V.    Loess  clay,  Guthrie  Center,  la. 

VI.   Pressed-brick  clay,  Rusk,  Tex. 


VII.  Brick  shale,  Mason  City,  la. 
VIII.  Calcareous  brick  clay,  Mil- 
waukee, Wis. 
IX.  Sandy  brick  clay,  Colmesneil, 

Tex. 
X.  Blue  shale  clay.    Ferris,  Tex. 


176  ECONOMIC  GEOLOGY 

II.  Glacial  clays,  found  in  the  drift,  and  often  stony.    May  either  be 

red-  or  cream-burning. 
III.  Wind-formed  deposits  (some  loess). 
D.  Chemical  deposits  (some  flint  clays?). 

Kinds  of  Clays.  —  Many  kinds  of  clays  are  known  by  special 
names,  which  in  some  cases  indicate  their  use,  but  in  others  refer 
partly  to  certain  physical  properties.  The  more  important  ones 
are  the  following  :  — 

Adobe.  A  sandy,  often  calcareous,  clay  used  in  the  west  and  south- 
west for  making  sun-dried  brick.  Ball  day.  A  white-burning,  plastic, 
sedimentary  clay,  employed  by  potters  to  give  plasticity  to  their  mixture. 
Brick  clay.  Any  common  clay  suitable  for  making  ordinary  brick.  China 
clay.  A  term  applied  to  kaolin  (q.v.).  Earthenware  clay.  Clay  suitable 
for  the  manufacture  of  common  earthenware,  such  as  flower  pots.  Fire 
clay.  A  clay  capable  of  resisting  a  high  degree  of  heat.  Flint  clay.  A 
peculiar  flint-like  fire  clay,  which  when  ground  up  and  wet  develops  no 
plasticity.  Chemically,  it  differs  but  little,  if  at  all,  from  the  plastic  fire 
clays.  Moreover,  the  two  often  occur  in  the  same  bed,  either  in  separate 
layers  or  irregularly  mixed.  Gumbo.  A  very  sticky,  highly  plastic  clay, 
occurring  in  the  central  states,  and  used  for  making  burned-clay  ballast  (2). 
Kaolin.  A  white-burning  residual  clay,  employed  chiefly  in  manufacture  of 
white  earthenware  and  porcelain.  The  term  is  also  applied  by  some  to  the 
white-burning  sedimentary  clays  of  Georgia  and  South  Carolina.  Loess.  A 
sandy,  calcareous,  fine-grained  clay,  covering  thousands  of  square  miles  in 
the  central  states,  and  of  wide  use  in  brick  making.  Paper  clay.  Any 
fine-grained  clay,  of  proper  color,  that  can  be  employed  in  the  manufacture 
of  paper.  Pipe  clay.  A  loosely  used  term  applied  to  any  smooth  plastic 
clay.  Strictly  speaking,  it  refers  to  a  clay  suited  to  the  manufacture  of  sewer 
pipe.  Pot  clay'.  A  dense-burning  fire  clay,  used  in  the  manufacture  of  glass 
pots.  The  domestic  supply  comes  mainly  from  St.  Louis,  Missouri,  but 
much  is  imported.  Pottery  clay.  Any  clay  suitable  for  the  manufacture  of 
pottery.  Retort  clay.  A  plastic  fire  clay,  used  in  making  gas  retorts.  The 
term  is  a  local  one  used  chiefly  in  New  Jersey.  Sagger  clay.  A  loose  term 
applied  to  clays  employed  in  making  saggers;  they  are  of  value  for  other 
purposes  as  well.  Sewer-pipe  clay.  A  term  applicable  to  any  clay  that  can 
be  used  for  manufacture  of  sewer-pipe.  It  is  usually  verifiable  and  red- 
burning.  Slip  clay.  Under  this  term  are  included  those  clays  which  are 
easily  fusible,  and  form  a  natural  glaze,  when  applied  to  ware  (such  as 
stoneware)  and  burned  at  the  proper  temperature.  The  best-known  variety 
comes  from  Albany,  N.  Y.  Stoneware  clay.  A  very  plastic  clay,  which 
burns  to  a  vitrified  or  stoneware  body.  It  may  be  refractory.  Terra-cotta 
clay.  Clay  suitable  for  the  manufacture  of  terra  cotta.  The  term  has 
no  special  significance,  as  a  wide  variety  of  clays  are  adapted  to  this 
purpose. 

Geological  Distribution.  —  Clays  have  a  wider  distribution  than 
most  other  economic  minerals  or  rocks,  being  found  in  all  forma- 


PLATE  XXI 


FIG.  1. — Kaolin  deposit,  North  Carolina,  shows  circular  pits  for  mining,  sunk  in 
clay.     (Photo  loaned  by  Southern  Railway  Company.) 


FIG.  2.  —  Bank  of  sedimentary  clay,  Woodbridge,  N.  J.     This  section  affords  at 
least  five  kinds  of  clay.     (Photo.,  H.  Ries.) 

(177) 


178 


ECONOMIC   GEOLOGY 


tions  from  the  oldest  to  the  youngest.  The  pre-Cambrian  crystal- 
lines yield  both  white  and  colored  residual  clays,  usually  the  result 
of  weathering,  though  more  rarely  of  solfataric  action.  In  the 
Paleozoic  rocks,  deposits  of  shale,  and  sometimes  of  clay,  are  found 
in  many  localities;  and,  since  they  are  usually  marine  sediments, 
the  beds  are  often  of  great  extent  and  thickness.  The  weathered 
outcrops  of  these  may  yield  a  residual  clay.  With  the  exception  of 
certain  Carboniferous  deposits,  the  Paleozoic  clays  are  mostly  im- 
pure. The  Mesozoic  formations  contain  large  supplies  of  clays 
and  shale  suitable  for  the  manufacture  of  bricks,  terra  cotta,  stone- 
ware, fire  brick,  etc. 

The  Pleistocene  clays  are  all  surface  deposits,  usually  impure, 
and  individually  of  limited  extent,  although  they  are  thickly  scat- 
tered all  over  the  United  States.  Their  chief  value  is  for  brick  and 
tile  making.  They  have  been  accumulated  by  glacial  action,  on 
flood  plains,  in  deltas,  or  in  estuaries  and  lakes. 

Distribution  of  Clays  by  Kinds  in  the  United  States. — Kaolins 
(67) .  —  Kaolins  proper  are  derived  only  from  crystalline  or  igneous 
rocks,  hence  their  distribution  is  limited,  and  the  only  deposits 
worked  are  in  the  eastern  states.  Being  commonly  formed 
by  the  weathering  of  pegmatite  veins,  kaolin  deposits  have  great 
length  as  compared  with  their  width,  which  may  be  anywhere 
from  5  to  300  feet.  Their  depth  ranges  from  20  to  120  feet, 
depending  on  the  depth  to  which  the  feldspar  has  been  weathered. 


CRUDE  KAOLIN 

WASHED  KAOLIN 

SiO2     

62.40 

45.78 

A12O3 

26.51 

36.46 

Fe2O3  

1.14 

.28 

FeO    

1.08 

CaO                                                       .     . 

.57 

.50 

MgO  

.01 

.04 

Alkalies    

.98 

.25 

HoO                                             .... 

8.80 

13.40 

Moisture 

.25 

2.05 

Clay  substance 

100.66 
66.14 

99.84 
93.24 

Quartz  and  white  mica  are  often  present  in  kaolin,  and  it  is  then  fre- 
quently necessary  to  put  the  clay  through  a  washing  process  to  remove  these 
minerals.  The  difference  between  a  washed  and  unwashed  kaolin  is  well 
shown  by  the  two  preceding  analyses,  from  which  it  is  seen  that  the  quartz 


CLAY  179 

contents  have  been  considerably  lowered,  and  that  the  washed  product 
approaches  more  closely  to  the  composition  of  kaolinite. 

North  Carolina  (52)  and  Pennsylvania  (58,  56)  are  the  most  im- 
portant residual  kaolin-producing  states,  but  deposits  are  also 
worked  in  Connecticut  (17  a),  Maryland  (36),  and  Virginia  (67). 
It  is  known  to  occur  in  Alabama  (10).  All  of  these  deposits  ex- 
cept that  in  Connecticut  are  found  south  of  the  limit  of  the  glacial 
drift.  Kaolins  occur  in  southeastern  Missouri,  but  they  have  never 
become  of  great  importance  (45). 

The  Cretaceous  of  Georgia  (20),  and  South  Carolina  (61) 
contains  important  deposits  of  white-burning  sedimentary  clays, 
which  might  perhaps  be  termed  plastic  kaolins  to  distinguish 
them  from  the  residual  ones. 

The  output  from  the  American  deposits  is  insufficient  to  supply 
the  domestic  clay-working  industry,  and  consequently  many  thou- 
sand tons  are  annually  imported  from  England.  Since  this  can  be 
brought  over  as  ballast,  it  is  possible  to  put  it  on  the  American 
market  at  a  low  price.  The  best  grades  of  kaolin  sell  for  $10  to 
$12  per  ton  at  Trenton,  New  Jersey,  and  East  Liverpool, 
Ohio,  these  being  the  two  most  important  pottery  centers  of  this 
country. 

Fire  Clays.  —  Fire  clays  are  found  in  the  rocks  of  all  systems, 
from  the  Carboniferous  to  the  Tertiary,  inclusive,  with  the  excep- 
tion of  the  Triassic. 

The  most  extensive,  and  among  the  most  important,  beds  of  fire 
clay  are  those  found  in  the  Carboniferous  strata  of  Pennsylvania 
(56,  60),  Ohio  (54,  55),  Kentucky  (29,  30,  33),  West  Virginia  (72), 
Maryland  (36),  Indiana  (24),  Missouri  (45),  and  Illinois  (21,  22). 
Those  of  the  first  two  named  states  are  on  the  average  the  most 
refractory.  Here  the  fire  clays  are  usually  found  underlying  coal 
seams  and  often  at  well-marked  horizons,  especially  in  the  Upper 
Productive  Measures. 

The  section  given  in  Fig.  2  is  fairly  representative  of  their  mode 
of  occurrence. 

Those  of  Indiana  and  Illinois  are  so  placed  that  one  mine  shaft 
may  be  used  for  extracting  coal,  fire  clay,  stoneware  clay,  and  shale. 

The  beds  of  refractory  clay,  found  in  the  Carboniferous  strata 
near  St.  Louis  (45),  are  not  only  used  in  the  manufacture  of  fire 
brick,  but  are,  in  some  cases,  found  suitable,  after  washing,  for 
mixture  with  imported  German  clays  for  the  manufacture  of  glass 
pots. 


180  ECONOMIC   GEOLOGY 

In  the  Lower  Cretaceous  of  New  Jersey  (49)  there  are  many  beds 
of  refractory  clay,  variable  in  thickness  and  closely  associated  with 
beds  of  less  refractory  character.  They  not  only  support  a  thriving 
local  fire-brick  industry,  but  serve  also  as  a  source  of  supply  for  fac- 
tories in  other  states.  Similar,  but  less  extensive  and  less  refractory, 
beds  occur  in  strata  of  Cretaceous  Age  in  the  coastal  plain  of  Mary- 
land (36),  Georgia  (20),  South  Carolina  (61),  and  Alabama  (10). 

The  Tertiary  formations  of  Texas  (64)  and  Mississippi  (44)  hold 
abundant  deposits  of  refractory  material,  but  many  are  undeveloped. 
The  Missouri  Tertiary  also  supplies  some  fire  clays  (45). 

Fire  clays  are  found  in  the  Black  Hills  of  South  Dakota  (62),  in  the 
Laram'ie  beds  of  Colorado  (14-17),  and  in  California  (13);  but,  excepting 
near  Denver,  where  used  for  making  fire  brick  and  assay er's  apparatus, 
these  deposits  are  as  yet  slightly  developed. 

Pottery  Clays.  —  Under  this  heading  are  included  several  grades 
of  clay,  the  kaolins,  already  described,  being  the  purest  and  best 
suited  to  the  manufacture  of  high  grades  of  pottery. 

Another  high-grade  pottery  clay  of  more  plastic  character,  the 
ball  clay,  is  of  limited  distribution  in  the  United  States.  A  small 
quantity  is  found  in  the  Cretaceous  (PL  XXI)  of  New  Jersey  (49), 
and  a  much  larger  amount  in  the  Tertiary  of  western  Kentucky 
(29,  31)  and  Tennessee  (63),  and  southeastern  Missouri  (45)  and 
Florida  (19,  67).  As  in  the  case  of  kaolin,  the  domestic  supply  is 
not  sufficient  to  meet  the  demand,  and  large  quantities  of  ball  clay 
are  imported  from  England. 

Stoneware  clays  form  a  third  grade  of  pottery  clays.  They  are 
usually  of  at  least  semirefractory  character,  but  differ  from  fire 
clays  proper  in  burning  dense  at  a  much  lower  temperature.  Their 
distribution  is  essentially  coextensive  with  that  of  fire  clays;  in- 
deed, the  two  are  often  dug  from  the  same  pit  or  mine.  Large 
quantities  are  obtained  in  the  Carboniferous  of  western  Pennsyl- 
vania (56,  57)  and  eastern  Ohio  (55)  and  smaller  amounts  in  the 
New  Jersey  Cretaceous  formations  (49). 

Stoneware  clays,  usually  in  the  same  area  as  the  fire  clays,  are  also  ob- 
tained in  Illinois  (21),  Indiana  (24),  Kentucky  (29,  31),  Tennessee  (63), 
Alabama  (10),  and  Texas  (64);  and  they  occur  also  in  Missouri  (45),  Iowa 
(26),  Colorado  (15),  and  California  (13). 

Many  of  the  Pleistocene  surface  clays  in  various  states  are  suffi- 
ciently dense-burning  to  be  used  locally  by  small  stoneware 
factories. 


CLAY  181 

Brick  and  Tile  Clays  (67) .  —  None  of  our  states  lack  an  abundant 
supply  of  good  brick  and  tile  clays,  and  in  many  areas  there  are 
extensive  deposits  near  the  large  markets,  and  often  near  tide 
water.  In  such  cases  the  clay  beds  are  exploited  to  an  enormous 
extent. 

In  the  northeastern  states  the  Pleistocene  surface  clays  are  found 
almost  everywhere  in  great  abundance,  and  are  made  use  of  in  many 
places,  especially  near  the  large  cities. 

In  the  middle  Atlantic  states  Columbian  loams  and  clay  marls  are 
an  important  source  of  brick  material. 

In  Ohio,  Illinois,  and  Indiana  Pleistocene  clays,  in  part  of  glacial, 
and  in  part  of  flood-plain  origin,  are  much  used  for  brick  and  tile. 
Impure  Paleozoic  shales  are  also  used  in  places,  especially  in  the 
manufacture  of  vitrified  paving  brick,  thousands  of  which  are  made 
annually  in  Ohio.  Northern  Illinois,  Michigan,  and  Wisconsin 
draw  their  main  supply  of  brick  clays  from  the  calcareous  lake 
deposits. 

Although  glacial  clays  and  flood-plain  deposits  are  much  used  in 
the  states  west  of  the  Mississippi,  the  loess  which  occurs  over  a  wide 
area  is  probably  even  more  important  as  a  source  of  brick,  while  in 
the  southwestern  states  loess  and  adobe  are  important.  Residual 
clays,  river  silts,  glacial  clays,  and  other  forms  of  clay  are  employed 
in  brick  making  along  the  Pacific  coast. 

Miscellaneous  Clays  of  Importance.  —  Paper  clays  of  good  quality  are 
much  sought  for  by  paper  manufacturers.  Much  English  kaolin  is  used 
for  this  purpose,  but  the  domestic  kaolins  are  also  drawn  upon,  especially 
those  of  Georgia,  South  Carolina,  North  Carolina,  southeastern  Pennsyl- 
vania, and  Connecticut.  A  small  amount  of  glasspot  clay  (45)  conies  from 
western  Pennsylvania,  but  much  more  from  eastern  Missouri,  and  our  chief 
supply  is  imported.  Terra-cotta  clays  are  obtained  from  the  same  areas  that 
supply  fire  clays,  New  Jersey  being  the  principal  producer. 

Distribution  of  Clays  in  Canada.  — -  Kaolins.  —  Deposits  are 
hardly  expected  in  the  glaciated  area,  but  one  deposit  formed 
from  feldspathic  veins  in  quartzite  has  been  worked  near 
Huberdeau,  Que.  (80). 

Fire  Clays.  —  Extensive  deposits  occur  in  the  Laramie  of 
southern  Saskatchewan  (79),  and  the  Eocene  delta  deposits  of 
the  Frazer  Valley,  British  Columbia.  The  same  materials  are 
utilized  for  pressed  brick,  terra  cotta,  and  certain  beds  for  stone- 
ware. 


182  ECONOMIC  GEOLOGY 

Red-burning  Clays  and  Shales.  —  The  Carboniferous  shales  of 
Nova  Scotia  and  New  Brunswick  (78,  81),  the  Ordovician  and 
Silurian  shales  of  Ontario  (77,  82),  and  the  Cretaceous  and 
Tertiary  shales  of  the  Western  Provinces  (79)  afford  abundant 
material  for  making  building  and  paving  brick,  drain  tile,  fire- 
proofing,  and  in  some  cases,  sewer  pipe. 

Surface  Clays.  —  These  are  widely  distributed  through  the 
Dominion,  and  may  be  of  the  estuarine,  lacustrine,  floodplain 
or  glacial  type  according  to  their  location  and  origin  (77-82). 
Those  found  in  the  Great  Plains  region  are  not  infrequently 
buff  or  cream  burning,  because  of  their  calcareous  nature. 

Other  Foreign  Deposits.  —  The  kaolin  or  china  clay  deposits 
of  the  Cornwall,  England,1  district  are  the  most  important  of 
this  type  worked  in  the  world,  and  supply  a  large  export  trade. 
Equally  well  known,  but  of  less  extent,  are  similar  deposits  in 
France,  Denmark,  Bohemia,  and  Germany.2  Fireclays  are 
worked  at  a  number  of  localities  for  domestic  use,  but  the  glass- 
pot  clays  of  Belgium  and  Germany  have  not  only  been  used  at 
home,  but  also  exported.  So,  too,  have  German  clays  employed 
in  making  graphite  crucibles. 

Uses  of  Clay.  —  So  few  people  have  even  an  approximate 
idea  of  the  uses  to  which  clays  are  put  that  it  seems  desirable 
to  call  attention  to  them  briefly.  In  the  following  table  an  attempt 
has  been  made  to  do  this :  3 — 

Domestic.  —  Pottery  of  various  grades;  Polishing  brick,  often  known  as 
bath  bricks;  Fire  kindlers;  Majolica  stoves. 

Structural.  —  Brick;  Tiles  and  Terra  cotta;  Chimney  pots;  Chimney  flues; 
Door  knobs;  Fireproofing;  Copings;  Fence  posts. 

Hygienic.  — Closet  bowls;  Sinks,  etc.;  Sewer  pipes;  Ventilating  flues;  Foun- 
dation blocks;  Vitrified  bricks. 

Decorative.  —  Ornamental  pottery;  Terrr  cotta;  Majolica;  Garden  furni- 
ture. 

Minor  Uses.  —  Food  adulterants;  Paint  filler;  Paper  filling;  Electrical  insu- 
lations; Pumps;  Fulling  cloth;  Scouring  soap;  Packing  horses'  hoofs; 
Chemical  apparatus;  Condensing  worms;  Ink  bottles;  Ultramarine 
manufacture;  Emery  wheels. 

Refractory  Wares.  —  Crucibles  and  other  assaying  apparatus;  Refractory 
bricks  of  various  patterns;  Glass  pots. 

Engineering  Work.  —  Puddle;  Portland  cement;  Railroad  ballast;  Water 
conduits;  Turbine  wheels. 

1  Searle,  British  Clays,  Shales  and  Sands,  London,  1911. 

2  Dammer  and  Tietze,  Die  Nutzbaren  Mineralien,  II:   379,  1914. 

3  Table  compiled  by  R.  T.  Hill  and  modified  by   the  author. 


CLAY 


183 


Production  of  Clay  and  Clay  Products.  —  Owing  to  the  fact 
that  clays  are  usually  manufactured  by  the  producer,  it  is 
necessary  to  give  the  value  of  the  product,  no  record  being  kept 
of  value  of  the  raw  material. 

VALUE  OF  CLAY  PRODUCTS  PRODUCED  BY  THE  NINE  LEADING  £TATES,  AND 
TOTAL  UNITED  STATES  PRODUCTION,  1910-1914 


STATE. 

1910 

1911 

1912 

1913 

1914 

Ohio     .     .     . 
Pennsylvania 
New  Jersey 
Illinois 
New  York 
Indiana    . 
Missouri  . 
Iowa    . 
California 

$31,525,948 
22,094,285 
17,834,309 
15,176,161 
11,871,949 
8,100,010 
7,087,766 
5,328,241 
4,842,391 

$32,663,895 
20,270,033 
18,178,228 
14,333,011 
10,184,376 
7,000,771 
6,274,353 
4,432,874 
4,915,866 

$34,811,508 
21,537,321 
19,838,553 
15,210,990 
12,058,858 
7,935,251 
6,412,861 
4,522,326 
5,912,450 

$38,388,296 
24,231,482 
19,705,378 
15,195,874 
11,469,476 
8,498,646 
6,602,076 
5,573,681 
5,344,958 

$37,166,768 
21,846,996 
16,484,652 
13,318,953 
9,078,933 
7,655,285 
6,077,284 
6,401,745 
1  5,761,  411 

Total     of     all 

states     . 

$170,115,974 

$162,236,181 

$172,811,275 

$181,289,132 

$164,986,983 

1  West  Virginia  in  1914  was  ninth  in  rank. 
VALUE  OF  CLAY  PRODUCTS,  BY  KINDS,  IN  THE  UNITED  STATES,  1910-1914 


KIND. 

1910 

1911 

1912 

1913 

1914 

Common  brick  . 

$55,219,551 

$49,885,262 

$51,796,266 

$50,134,757 

$43,769,524 

Vitrified      paving 

brick     . 

11,004,666 

11,115,742 

10,921,575 

12,138,221 

12,500,866 

Front  brick  .      . 

8,590,057 

8,648,877 

9,455,297 

9,614,138 

9,289,623 

Ornamental  brick 

179,505 

177,015 

225,367 

109,703 

124,459 

Enameled  brick  . 

832,225 

1,038,865 

1,027,314 

1,225,708 

1,075,026 

Firebrick 

18,111,474 

16,074,686 

17,877,629 

20,627,122 

16,427,547 

Stove  linings 

503,806 

614,116 

516,874 

535,667 

520,585 

Drain  tile 

10,389,822 

8,826,314 

8,010,250 

8,558,320 

8,522,039 

Sewer  pipe    . 

11,428,696 

11,454,616 

12,147,677 

14,872,103 

14,014,767 

Architectural 

terra  cotta 

6,976,771 

6,017,801 

8,580,436 

7,733,306 

6,087,652 

Fireproofing 

5,110,597 

5,660,172 

7,174,148 

8,620,216 

8,385,337 

Tile  (not  drain) 

5,240,644 

5,356,184 

5,809,495 

6,109,180 

5,705,583 

Pottery     .     .      . 

33,784,678 

34,518,560 

36,504,164 

37,992,375 

35,398,161 

Much  clay  is  mined  and  sold,  especially  to  manufacturers  of 
high-grade  clay  products  who  do  not  own  deposits  themselves. 
The  value  of  production  of  suc^i  clays  is  given  below. 

VALUE  OF  CLAYS  MINED  AND  SOLD  IN  THE  UNITED  STATES,  1910-1914 


KIND. 

1910 

1911 

1912 

1913 

1914 

Kaolin      
Paper  clay    .... 
Slip  clay  .      .      . 

$    255,873 
420,476 
29,962 

$    211,045 
454,435 
16,770 

$    220,747 
522,924 
27,573 

$    235,457 
567,977 
24,505 

$    284,817 
558,334 
17,731 

Ball  clay  
Fire  clay  

257,265 
2,157,720 

220,710 
2,112,827 

227,545 
2,363,357 

237,672 
2,592,591 

255,767 
2,147,277 

Stoneware  clay 
Brick  clay     .... 
Miscellaneous  . 

153,044 
128,039 
223,106 

165,751 
123,900 
165,325 

115,522 
204,504 
263,848 

143,587 
137,976 
240,694 

116,610 
161,852 
214,180 

Total    

$3,625,485 

$3,480,763 

$3,946,020 

$4,180,459 

$3,756,568 

184 


ECONOMIC   GEOLOGY 


PRODUCTION  OF  CLAY  PRODUCTS  IN  CANADA,  1912-1914 


1912 

1913 

1914 

NUMBER 

VALUE 

1  NUMBEH 

VALUE 

2  NUMBER 

VALUE 

Brick,  common 

769,191,532 

$7,010,375 

668.426,675 

$5,917,373 

457,513,762 

$3,653,861 

Brick,  pressed   . 

125,180,422 

1,609,854 

116,802,053 

1,458,733 

93,634,858 

1,115,556 

Brick,  paving    . 

4,579,500 

85,989 

4,208,295 

75,669 

2,707,000 

49,627 

Brick,  moulded  & 

ornamental    . 

371,356 

8,595 

875,355 

15,423 

1,554,496 

23,592 

Firebrick  and  fire- 

clay shapes,  etc. 



125.585 



i  142,738 

. 

1  107,568 

Fireproofing    and 

architectural 

terra-cotta 



448,853 



461,387 



405,543 

Kaolin  (tons)     . 

20 

160 

500 

i  5,000 



10,000 

Pottery     .      .     f. 



43,955 



53,533 



35,371 

Sewer  pipe    . 



834,641 



1,035,906 



1,104,499 

Tile,  drain    .     . 



357,862 



338,552 



366,340 

Total     .     . 



10,575,869 

9,504,314 

$6,871,957 

1  Production' from  Canadian  clay. 


2  Number  sold. 


The  total  value  of  the  exports  of  Canadian  clay  products  in 
1914  was  $48,073. 

The  imports  of  Canadian  clays  and  clay  products  in  1914  were 
valued  at  $4,467,140.  Both  imports  and  exports  less  than  1913. 

REFERENCES   ON   CLAY 

TECHNOLOGY  AND  PROPERTIES.  1.  Ashley,  U.  S.  Geol.  Surv.,  Bull.  388, 
1909.  (Colloid  matter.)  2.  Bain,  Min.  Indus.,  VI:  157,  1898.  (Clay 
ballast.)  3.  Binns,  Potters'  Craft.  (Van  Nostrand  &  Co.)  3a.  Buck 
man,  Amer  Ceram.  Soc.,  Trans.,  XIII:  336,  1911.  (Formation  of 
residual  clay.)  4.  Bourry,  Treatise  on  Ceramic  Arts,  N.  Y.  (Van 
Nostrand  &  Co.),  London  (Scott  Greenwood  &  Co.),  1901.  5.  Bischof, 
Die  Feuerfesten  Thone,  3d  ed.,  Leipzig,  1904  (Quandt  &  Handel), 
12  Mks.  6.  Branner,  Bibliography  of  Clays  and  the  Ceramic  Arts, 
American  Ceramic  Society,  1906.  6a.  Davis,  Amer.  Inst.  Min.  Engrs., 
Bull.  98,  1915.  (Plasticity  and  origin.)  7.  Galpin,  Amer.  Ceram. 
Soc.,  Trans.  XIV:  301,  1902.  (Flint  clays.)  8.  Ries,  Clays,  Occur- 
rence, Properties,  and  Uses,  2d  ed.,  N.  Y.,  1908  (Wiley  &  Sons.)  80. 
Merrill,  Rocks,  Rock  Weathering  and  Soils,  2d  ed.,  N.  Y.  (Macmillan 
Co.)  9.  Wheeler,  Vitrified  Paving  Brick,  Indianapolis,  1895  (Clay- 
worker  Pub.  Co.),  $1.00.  9a.  Ries  and  Leighton,  History  of  Clay 
Working  Industry  in  United  States.  (Wiley  &  Sons.)  Many  excellent 
papers  in  Transactions  American  Ceramic  Society,  Vols.  1-17  of  which 
have  appeared.  See  also  Nos.  26,  36,  49,  51  for  general  properties  and 
technology. 

AKEAL  REPORTS.  Alabama:  10.  Smith  and  Ries,  Ala.  Geol.  Surv.,  Bull. 
6,  1900.  (General.)  —  Arkansas:  11.  Branner,  U.  S.  Geol.  Surv., 
Bull.  351,  1908.  12.  Also  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVII. 
42,  1898.  (S.  W.  Ark.)  —  California:  13.  Johnston,  Calif.  State  Min- 
eralogist, 9th  Ann.  Kept.:  287,  1890.  (General.)  See  also  scattered 
notices  in  other  annual  reports.  —  Colorado:  14.  Eldridge,  U.  S. 


CLAY  185 

Geol.  Surv.,  Mon.  XXVII,  1896.  (Denver  Basin.)  15.  Geijsbeek, 
Clay  Worker,  XXXVI:  424,  1901.  (General.)  16.  Ries,  Amer.  Inst. 
Min.  Engrs.,  XXVII:  336,  1898.  (Clays  and  Clay  industry.)  17. 
Shaler  and  Gardner,  U.  S.  Geol.  Surv.,  Bull.  315:  296,  1906.  —  Con- 
necticut: 17a.  Loughlin,  Conn.  Geol.  Surv.,  Bull.  4,  1905.  —  Delaware: 
18.  Booth,  Geol.  of  Delaware:  94  and  106,  1841. —Florida:  19.  Ries, 
U.  S.  Geol.  Surv.,  Prof.  Pap.  11:  81,  1903.  19a.  Matson,  U.  S.  Geol. 
Surv.,  Bull.  380:  346,  1909.  —  Georgia:  20.  Veatch,  Ga.  Geol.  Surv., 
Bull.  18,  1909.  —  Illinois:  21.  Many  scattered  references  in  volumes  on 
Economic  Geology  of  Illinois  Geol.  Survey,  Resume  of  these  in  U.  S. 
Geol.  Surv.,  Prof.  Pap.  11,  1903.  22.  Purdy  and  De  Wolf,  111.  Geol. 
Surv.,  Bull.  4:  131,  1907.  (Fire  clays.)  23.  Rolfe  and  others,  Ibid., 
Bull.  9,  1908.  (Paving-brick  clays.) — Indiana:  24.  Blatchley,  Ind. 
Dept.  GeoL  and  Nat.  Hist.,  20th  Ann.  Rept. :  23,  1896.  (Carboniferous 
clays.)  25.  Same  author,  22d  Ann.  Rept.:  105,  1898.  (N.  W.  Ind.) 
Scattered  references  in  other  annual  reports. — Iowa:  26.  Beyer, 
Williams,  and  W^eems,  la.  Geol.  Survey,  XIV:  29,  1904. —  Kansas: 

27.  Prosser,  U.  S.  Geol.  Surv.,   Mineral  Resources,   1892:    731,  1893. 

28.  See  also  Reports  on  Mineral  Resources  of  Kansas,  Kas.  Geol.  Sur- 
vey, 1897-1901.  — Kentucky:    29.  Ries,  U.  S.  Geol.  Surv.,  Prof.  Pap. 
11,    1903.     30.  Many  analyses  in  Ky.  Geol.  Surv.,   Chem.  Rept.  A, 
pts.   1,   2,   and  3,   1885,    1886,    1888.     31.  Gardner,   Ky.  Geol.  Surv., 
Bull.   6,    1905.     (Western  coal  field   and   Jackson   Purchase   Region.) 

32.  Foerste,  Ibid.     (Silurian,  Devonian,  Waverly,  Irvine  formations.) 

33.  Phalen,   U.  S.   Geol.   Surv.,   Bull.  285:    411,   1906.     (N.  E.  Ky.) 
33a.  Easton,  Ky.  Geol.  Surv.,  4th  ser.,  I:   713,  1913  and  Crider,  Ibid.: 
589.     (N.  E.  Ky.) — Louisiana:    34.  Clendenin,  Eng.  and  Min.  Jour., 
LXVI:    456,  1898.     35.  Ries,  Preliminary  Report  on  Geology  of  La., 
I:   264,  1899. —  Maryland:    36.  Ries,  Md.  Geol.  Survey,  IV,  Pt.  Ill: 
205,  1902.  —  Massachusetts:    37.  Crosby,  Technol.  Quart.,  Ill:    228, 
1890.     (Kaolin  at  Blandford.)     38.  Shaler,  Woodworth,  and  Marbut, 
U.  S.  Geol.  Surv.,   17th  Ann.  .Rept.,  I:    957,  1896.     (R.  I.  and  S.  E. 
Mass.)     39.  Whittle,  Eng.  and  Min.  Jour.,  LXVI:  245,  1898.  —  Mich- 
igan:   40.  Ries,  Mich.  Geol.    Surv.,  VIII:     Pt.  I,   1903.     (Clays  and 
shales.)  —  Minnesota:    41.  Grout  and  Soper,  Minn.  Geol.  Surv.,  Bull. 
11,  1914.     42.  Winchell,  Minn.  Geol.  Surv.,  Misc.  publications,  No.  8, 
1881.     (Brick   Clays.)  —  Mississippi:     43.  Logan,    Miss.    Geol.    Surv., 
Vol.  2,    No.   3,  1905.     (N.  W.  Miss.)     44.  Logan,  Miss.  Geol.  Surv., 
Bull.  6,   1909. —  Missouri:    45.  Wheeler,  Mo.  Geol.  Surv.,  XI,   1896. 
(General.)  — Nebraska:    46.  Neb.   Geoi.  Surv.,  I:    202,  1903.  — New 
Hampshire:    47.  Hitchcock  and  Upham,  Report  on  Geology  of  New 
Hampshire,  V:   85,  1878. —New  Jersey:   48.  Cook,  N.  J.  Geol.  Surv., 
1878.     (Special  Report  on  Clays.)     49.  Kiimmel,  Ries,  Knapp,  N.  J. 
Geol.  Surv.,  Final  Reports,  VI,  1904.  —  New  Mexico:    50.  Shaler  and 
Gardner,  U.  S.  Geol.  Surv.,  Bull.  315:  296,    1906.     (Durango-Gallup 
field.)  —  New  York:  51.  Ries,  N.  Y.  State  Museum,  Bull.  35,  1900.  (Gen- 
eral.)—North  Carolina:    52.  Ries,  N.  Ca.  Geol.  Surv.,  Bull.  13,  1897. 
(General.)  —  North  Dakota:  53.  Babcock  and  Clapp,  N.  D.  Geol.  Surv., 
4th   Bien.    Rept.,    1906.     (General.)  —  Ohio:    54.  Orton,    Ohio   Geol. 


186  ECONOMIC  GEOLOGY 

Surv.,  VII:  45,  1893.  (Geology.)  55.  Orton,  Jr.,  Ibid.,  p.  69.  (Clay 
industries.)  —  Oklahoma:  55a.  Snider,  Okla.  Geol.  Surv.,  Bull.  7, 
1911.  — Oregon:  556..  Williams,  Min.  Res.  Ore.,  I,  No.  7:  14,  1914. 
—  Pennsylvania:  56.  Hopkins,  Pa.  State  College,  Ann.  Repts.  as 
follows,  1897,  Appendix.  (W.  Pa.)  Ibid.,  Append,  to  Rept.  for  1899- 
1900.  (Philadelphia  and  vicinity.)  57.  Ibid.,  1898-1899.  (S.  E.  Pa.) 
58.  Many  analyses  in  2d  Pa.  Geol.  Surv.,  Rept.  MM:  257,  1879,  and 
scattered  references  in  Repts.  H  5,  H  4,  C  4,  C  5,  etc.  59.  Resume 
in  U.  S.  Geol.  Surv.,  Prof.  Pap.  11:  208,  1903.  60.  Scattered  papers 
in  U.  S.  Geol.  Surv.,  Bulls.  285,  279,  315,  256,  225.  —  South  Carolina: 

61.  Sloane,   Bull.   I,   S.   Ca.   Geol.   Surv.,     (S.   Ca.)  —  South  Dakota: 

62.  Todd,  S.  D.  Geol.  Surv.,  Bull.  3:    101.  —  Tennessee:    63.  Nelson, 
Min.  Res.  Tenn.,  II,  No.  4,   1912.     (W.  Tenn.),   and  No.   11    (Henry 
County.)  —  Texas:  64.  Univ.  of  Tex.,  Bull.  102,  1908.  —  United  States: 
65.  Hill,   U.   S.   Geol.   Surv.,    Min.   Res.    1891:    474,    1893.     66.  Ries, 
U.  S.  Geol.  Surv.,  17th  Ann.  Rept.,  Ill:    845,1  896.     (Pottery   clays.) 
67.  Ries,    U.   S.    Geol.   Surv.,   Prof.   Pap.    11,     1903.      (Clays  east   of 
Mississippi    River.)  —  Vermont:     68.  Nevius,    Eng.    and    Min     Jour., 
LXIV:    189,  1897.     (Kaolin.)     69.  Ries,  U.  S.  Geol.  Surv.,  Prof.  Pap., 
11:    133,   1903. —Virginia:    70.  Ries,  Va.  Geol.  Surv.,   Bull.  2,  1906. 
(Coastal  Plain.)—  Washington:    71.  Shedd,  Rept.  State  College,  1910. 
(General.)  —  West  Virginia:    72.  Grimsley  and  Grout,   W.  Va.  Geol. 
Surv.,    Ill,    1906. —Wisconsin:     73.  Buckley,    Wis.    Geol.    and   Nat. 
Hist.  Surv.,  Bull.  7,  Pt.  I,  Eco.  Series,  4,  1901.     (General.)     74.  Ries, 
Wis.    Geol.    Surv.,    Bull.    15,    1906. —  Wyoming:     75.  Knight,    Wyo. 
Experiment    Station,    Bull.    14,    1893.     (General.)     76.  Fisher,    U.    S. 
Geol.  Surv.,  Bull.  260:  559,  1905. 

Canada:  77.  Baker,  Ont.  Bur.  Mines,  XV,  Pt.  II,  1906.  (Ont.)  78.  Ries, 
Can.  Geol.  Surv.,  Mem.  16-E,  1911.  (N.  S.  and  N.  B.)  79.  Ries  and 
Keele,  Ibid.,  Mem.  24-E,  25  and  47.  (Western  Provinces.)  80.  Keele, 
Ibid.,  Mem.  52,  1915.  (Que.)  81.  Keele,  Ibid.,  Mem.  44,  1914.  (N. 
B.)  82.  Keele,  Ibid.,  Summary  Rept,,  1914:  87,  1915,  (Ont.) 


CHAPTER  V 
LIMES  AND  CALCAREOUS  CEMENTS 

Composition  of  Limestones  (2,  43).  —  Limes  and  calcareous 
cements  form  an  important  class  of  economic  products,  obtained 
from  limestones  by  heating  them  to  a  temperature  ranging  from 
that  of  decarbonation  to  clinkering.  The  term  limestone  is  applied 
to  one  of  the  main  divisions  of  the  stratified  rocks  so  widely  distrib- 
uted, both  geologically  and  geographically,  and  formed  under  such 
different  conditions,  that  its  composition  varies  greatly,  this  range 
of  variation  becoming  appreciable  from  an  inspection  of  the  follow- 
ing table,  which  contains  a  few  selected  types :  — 


I 

II 

III 

IV 

v 

VI 

VII 

VIII 

Silica  (SiO2)      .     .     . 

.54 

2.22 

.48 

4.9 

14.30 

15.05 

16.99 

12.13 

Alumina  (AlsOs)    .     ." 

1     !o 

f.92 

!on 
..0 

«   FC 

.70 

9.02 

5.00 

4.17 

Ferric  oxide  (Fe2O3)    . 

[.18 

.80 

1.27 

1.79 

3.28 

Lime  (CaO)      .     .     . 

54.73 

54.08 

31.31 

27.3 

46.50 

39.26 

23.15 

42.04 

Magnesia    (MgO) 

.19 

.10 

21.03 

14.6 

n.d. 

1.90 

16.60 

.44 

Sulphur  trioxide  (SOs) 

— 

— 

— 

— 

— 

— 

— 

n.d. 

Carbon  dioxide  (CO2) 

43.22 

42.50 

46.98 

44.8 

36.54 

32.90 

36.47 

33.51 

Water  (H2O)    .     .     . 

— 

— 

— 

— 

— 

— 

— 

— 

99.10 

100.00 

99.99 

98.1 

98.84 

99.40 

100.00 

95.57 

I.  Pure  limestone,  Ilasco,  Mo.  II.  Chalk,  Marinas,  Cuba.  III.  Dolomite, 
E.  Canaan,  Conn.  IV.  Magnesian  limestone,  Clinton,  Hunterdon  Co.,  N.  J. 
V.  Siliceous  limestone  for  hydraulic  lime,  Teil,  France.  VI.  Argillaceous  (cement 
rock)  limestone,  Lehigh  district,  Pa.  VII.  Argillaceous  magnesian  limestone, 
Milwaukee,  Wis.  VIII.  Clayey  chalk. 

From  this  table  it  will  be  seen  that  limestones  vary  from  rocks 
composed  almost  entirely  of  carbonate  of  lime,  or  of  carbonate  of 
lime  and  carbonate  of  magnesia,  to  others  which  are  high  in  clayey 
or  siliceous  impurities.  The  presence  of  such  impurities  in  large 
quantity  usually  imparts  an  earthy  appearance  to  the  limestone, 
and  sometimes  even  gives  it  a  shaly  structure. 

Marked  variations  in  composition  may  at  times  be  found  even 
in  a  single  quarry  (50),  while  in  other  cases  a  limestone  formation 
may  show  remarkable  uniformity  of  composition  over  a  wide  area. 

187 


188  ECONOMIC  GEOLOGY 

Changes  in  Burning  (2).  —  When  limestones  are  calcined  or 
"  burned  "  to  a  temperature  sufficiently  high  to  drive  off  volatile 
constituents,  such  as  carbon  dioxide,  water,  and  sulphur  (in  part), 
or,  in  other  words,  to  the  point  of  decarbonation,  the  rock  is  left  in 
a  more  or  less  porous  condition.  If  heated  to  a  still  higher  tem- 
perature, the  rock  clinkers  or  fuses  incipiently,  but  the  temperature 
of  clinkering  depends  on  the  amount  of  siliceous  and  clayey  im- 
purities in  the  rock. 

Lime  (2,  43).  —  Limestone  free  from  or  containing  but  a  small 
percentage  of  argillaceous  impurities  is,  by  decarbonation,  changed 
to  quicklime,  a  substance  which  has  a  high  affinity  for  water,  and 
which,  when  mixed  with  water,  "  slakes,"  forming  a  hydrate  of  lime. 
This  change  is  accompanied  by  the  evolution  of  heat  and  by  swell- 
ing, and  this  action  becomes  the  more  marked  the  higher  the  per- 
centage of  lime  carbonate  in  the  rock,  for  the  slaking  activity 
is  retarded  by  the  presence  of  magnesia  and  especially  by  argil- 
laceous impurities.  Limes  may,  therefore,  be  divided  into 
"  f at  "  limes  and  "  meager  "  limes,  depending  on  the  rapidity 
with  which  they  slake  and  the  amount  of  heat  they  develop  in 
doing  so. 

Hydraulic  Cements.  —  With  an  increase  in  clayey  and  siliceous 
impurities,  one  burned  rock  shows  a  decrease  in  slaking  qualities, 
and  develops  hydraulic  properties,  or  sets  when  mixed  with  water, 
and  even  under  the  same.  Products  of  this  type  are  termed  ce- 
ments, and  owe  their  hydraulic  properties  to  the  formation  during 
burning  of  silicates  and  aluminates  of  lime.  On  mixing  the  burned 
ground  rock  with  water,  these  take  up  the  latter  and  crystallize, 
thereby  producing  the  set  of  the  cement. 

Hydraulic  cements  can  be  divided  into  the  following  classes: 
Pozzuolan  cements,  hydraulic  limes,  natural  cements,  and  Portland 
cements. 

Pozzuolan  Cement  (2,53).  —  This  is  produced  from  an  uncal- 
cined  mixture  of  slaked  lime  and  a  sili co-aluminous  material,  such 
as  volcanic  ash  or  blast-furnace  slag. 

This  process  was  known  to  the  ancients,  and  is  named  from  its 
early  use  around  Pozzuolano,  Italy.  The  composition  of  an  Italian 
Pozzuolano  earth  may  vary  between  the  following  limits:1  SiO2, 
52-60;  A12O3,  9-21;  Fe2O3,  5-22;  CaO,  2-10;  MgO,  up  to  2;  al- 
kalies, 3-16;  H2O,  up  to  12. 

1  Schoch,  Die  Moderne  Aufbereitung  u.  Wert,ting  der  Mortel  Materialien,  Berlin. 
1896. 


LIMES  AND   CALCAREOUS  CEMENTS 


189 


No  deposits  of  volcanic  ash,  for  use  in  Pozzuolan  cement,  are 
worked  in  the  United  States,  although  extensive  deposits  of 
the  material  are  known  to  occur  in  the  Rocky  Mountain  and 
Pacific  Coast  states.  It  is  said,  however,  that  a  mixture  of 
Portland  cement  and  volcanic  ash  was  extensively  and  satis- 
factorily used  in  the  construction  of  the  Los  Angeles  aque- 
duct. 

The  manufacture  of  slag  cement  has  been  started  at  several 
localities  in  the  United  States  (2),  but  the  industry  is  at 
present  showing  a  contraction  instead  of  an  expansion.  More- 
over, the  cement  hardly  meets  the  specifications  for  Portland 
cement. 

Hydraulic  limes  (2)  are  formed  by  burning  a  siliceous  limestone 
to  a  temperature  not  much  above  that  of  decarbonation.  Owing 
to  the  high  percentage  of  lime  carbonate,  considerable  free  lime 
appears  in  the  finished  product.  Hydraulic  limes  generally  have  a 
yellow  color,  and  a  gravity  of  about  2.9.  They  slake  and  set  slowly, 
and  have  little  strength  unless  mixed  with  sand.  This  class  is  of 
little  importance  in  the  United  States,  although  small  quantities 
have,  in  the  last  few  years,  been  produced  in  Maryland,  Georgia, 
and  New  York.  They  are,  however,  of  great  importance  in  Europe, 
and  it  may  be  of  interest  to  give  a  few  analyses  of  the  raw  material 
used  abroad  (2) : 

ANALYSES  OF  HYDRAULIC  LIME  ROCKS 


1 

2 

3 

4 

Silica  (SiOo)      

14.30 

11.03 

7.60 

17.00 

Alumina  (AloOs) 

.70 

3.75 

] 

1.00 

Iron  oxide  (Fe2Os)         .... 
Lime  (CaO)     

.80 
46.50 

5.07 
43.02 

}     •'* 

50.05 

44.80 

Magnesia  (MgO) 

undet 

1.34 

.30 

.71 

Carbon  dioxide  (CO2)    .... 
Water 

36.54 

35.27 

41.30 

35.99 

1.  Teil,  France.     2.  Hausbergen,  Germany.    3.   Malain,  France.    4.  Se- 
nonches,  France. 

In  the  best  types  of  hydraulic  limestones,  silica  varies  between 
13  and  17  per  cent,  while  alumina  and  iron  oxide  together  rarely 
exceed  3  per  cent. 


190 


ECONOMIC   GEOLOGY 


Natural  Rock  Cements  (2,  43) .  —  These,  known  also  as  Roman 
cement,  quick-setting  cement,  and  Rosendale  cement,  are  made  by 
burning  a  silico-aluminous  limestone  (containing  from  15  to  40  per 
cent  clayey  impurities)  at  a  temperature  between  decarbonation 
and  clinkering.  The  product  shows  little  or  no  free  lime.  The 
following  analyses  will  give  some  idea  of  the  range  in  composition  of 
natural  cement  rocks  quarried  in  the  United  States :  — 

ANALYSES  OF  NATURAL  CEMENT  ROCKS 


UTICA, 
ILL. 

LOUIS- 
VILLE 
DISTRICT 

FORT 
SCOTT, 
KAN. 

HANCOCK, 
MD. 

HANCOCK, 
MD. 

MANKA- 

TO, 

MINN. 

SiO2                      .     •     . 

17.01 

15.21 

17.26 

19.81 

24.74 

10.10 

AloOs 

335 

4.07 

205 

7.35 

16.74 

2  78 

FeaOs      .     .    .    .     .     . 

2.39 

1.44 

5.45 

2.41 

6.30 

1.34 

CaO  

32.85 

33.99 

34.45 

35.76 

23.41 

25.96 

MgO 

845 

7.57 

5.28 

2.18 

4.09 

1491 

Alk  .." 

n.d. 

n.d. 

6.18 

3.50 

SO3              .         ... 

1.81 

n.d. 

2.22 

.26 

CO»    1 

f  35.03 

32.87  1 

r,     f 

22.90 

41.29 

HoO                                 \ 

34.12 

31.74 

LAW- 

RENCE- 
VILLE, 

N.Y. 

LAW- 

RENCE- 
VILLE, 

N.Y. 

HOWES 
CAVE, 

N.Y. 

JAMES- 

VILLE, 

N.Y. 

AKRON- 
BUFFALO 
DISTRICT 

MIL- 
WAUKEE, 
Wis. 

SiO2                       ... 

1090 

2380 

12  89 

1097 

903 

17  56 

A12O3      

3.40 

4.17  1 

f    446 

225 

1  40 

FeaOs      ...'... 

228 

, 
4  71 

11.15 

1  54 

85 

224 

CaO 

2957 

2227 

3090 

27  51 

26  84 

27  14 

MgO  
Alk  

14.04 
nd 

12.09 
nd. 

9.38 

16.90 

18.37 

85 

13.89 

SO3 

61 

90 

nd 

CO2    ' 

37.90 

31.00 

3460 

3794 

4033 

3645 

HoO   

n.d 

nd 

98 

Natural  cements  differ  from  lime  in  possessing  hydraulic  prop- 
erties, and  refusal  to  slake  unless  ground  very  fine.  They  differ 
from  Portland  cements  in  lighter  weight,  lower  temperature  of 
burning,  quicker  set,  lower  ultimate  strength,  and  greater  latitude 
of  composition.  Magnesia  is  not  regarded  as  a  detrimental  im- 
purity in  natural  cements  as  it  is  in  Portland  cement. 


LIMES   AND   CALCAREOUS  CEMENTS 


191 


The  f ollowing  are  some  analyses  of  the  burned  material :  — 
ANALYSES  OF  SOME  NATURAL  ROCK  CEMENTS 


CaO 

MgO 

SiO2 

A1203 

Fe,O3 

Na20,K2O 

IGNITION 

Natural   rock   cement, 

Rosendale,  N.  Y. 

34.38 

18 

30.5 

6.84 

2.42 

3.98 

3.78 

Natural   rock   cement, 

Akron,  N.  Y.    .     . 

40.68 

22 

22.62 

7.44 

1.40 

2.23 

3.63 

Natural   rock   cement, 

Cumberland,  Md. 

43.97 

2.21 

22.38 

11.71 

2.29 

9.00 

2.44 

Roman    cement,     Rii- 

dersdorf,  Germany 

56.45 

4.84 

27.88 

6.19 

4.64 

— 

— 

Portland  Cement  (2) .  —  Portland  cement  is  the  product  obtained 
by  burning  a  finely  ground  artificial  mixture  consisting  essentially 
of  lime,  silica,  alumina,  and  some  iron  oxide,  these  substances  being 
present  in  certain  definite  proportions.  Portland  cement  was  first 
made  by  Joseph  Apsdin,  of  Leeds,  England,  who  desired  to  make  an 
artificial  cement  that  would  replace  natural  hydraulic  cements.  It 
received  its  name  because  it  hardened  under  water  to  a  mass.  resen> 
bling  the  Portland  stone  of  England. 

The  following  combinations  of  raw  materials  are  at  present  used 
in  the  manufacture  of  true  Portland  cement  in  the  United  States: 
bog  lime  and  clay;  limestone  and  clay,  or  shale;  chalk  and  clay; 
pure  limestone  and  argillaceous  limestone. 

In  these  combinations  it  is  evident  that  the  substances  first  named 
supply  most  of  the  lime  and  the  second  most  of  the  silica,  alumina,  and  iron. 
In  the  fourth  the  argillaceous  limestone  supplies  some  lime,  as  well  as  the 
silica  and  alumina.  The  nature  of  the  raw  materials  chosen  depends  to  a 
large  degree  on  the  location  of  the  plant,  whether  in  a  limestone-  or  a  bog- 
lime-producing  region.  Where  both  of  these  raw  materials  are  available, 
as  in  parts  of  New  York,  questions  of  manipulation  in  the  process  of  man- 
ufacture govern  the  selection  of  one  or  the  other. 

Bog  limes,  for  example,  though  easier  to  excavate  and  reduce  than  lime- 
stones, contain  so  much  more  organic  matter  and  water  than  limestones  that 
they  are  more  expensive  to  handle  and  prepare.  Bog  lime  beds  are  likewise 
apt  to  be  of  limited  extent  and  irregular,  while  limestone  beds  are,  so  far  as 
the  needs  of  a  manufacturing  plant  are  concerned,  practically  limitless. 

Comparing  clay  and  shale,1  the  former  is  often  easier  to  excavate, 
but,  on  account  of  the  water  it  contains,  has  to  be  dried  before  it  can  be 
ground  and  mixed.  The  fossils  in  shales  are  sometimes  an  important 
source  of  calcium  carbonate,  and  then  careful  grinding  and  mixing  is  neces- 

i  It  is  probable  that  the  refuse  of  many  slate  quarries  could  also  be  used  in 
place  of  shale. 


192 


ECONOMIC  GEOLOGY 


sary  to  bring  about  a  uniform  distribution  of  the  lirne  through  the  mass. 
Shale  is,  however,  used  by  only  a  few  works. 

Argillaceous  limestone,  mixed  with  a  much  smaller  quantity  of  purer 
limestone,  as  in  Pennsylvania  and  New  Jersey,  is  superior  to  a  limestone 
and  clay  mixture,  because  less  thorough  mixing  and  fine  grinding  are  re- 
quired. In  such  cements,  even  when  grinding  and  mixing  are  incompletely 
done,  the  particles  of  argillaceous  limestone  so  closely  resemble  the  proper 
mixture  in  chemical  composition  as  to  affect  the  result  but  little. 

The  following  table  gives  the  analyses  of  some  of  the  raw  materials 
used  in  manufacture  of  Portland  cement :  — 

ANALYSES  OF  RAW  MATERIALS  USED  FOR  PORTLAND  CEMENT 


LOCALITY 

MATERIAL 

SiO2 

AI203 

Fe203 

CaCO3 

MgC03 

H,0  + 
ORG. 
MATTER 

MlSCEL. 

Calc.  shale 

Lehigh 

or 

• 

CaS04 

Valley, 

T-\ 

cement  rock 

15.40 

4.26 

1.38 

74.66 

2.66 

1.88 

.86 

Penn. 

Limestone 

5.87 

1.59 

88.00 

4.00 

mixture 

13.97 

5.07 

1.88 

74.1 

2.04 

1.82 

Glens 

CaO 

MgO 

SO3 

Falls, 

Limestone 

3.3 

1.3 

52.15 

1.58 

.3 

N.  Y. 

CaO 

MgO 

S03 

Clay 

55.27 

28.15 

5.84 

2.25 

8.37 

.12 

Warners, 

Bog  lime 

.26 

.10 

94.39 

.38 

4.64 

N.Y. 

Clay 

40.48 

20.95 

25.80 

.99 

8.50 

Insol. 

CaSO4 

Sandusky, 

Bog  lime 

1.28 

1.72 

92.70 

.50 

1.13 

2.06 

Ohio 

CaO 

MgO 

Clay 

64.70 

11.9 

9.9 

.90 

.70 

11.9 

White 

r  Chalk 

7.97 

1.09 

88.64 

.73 

Cliffs, 
Ark. 

I  Clay 

53.3 

23.29 

9.52 

CaO 
.36 

MgO 
1.49 

5.16 

In  the  selection  of  the  raw  materials  the  aim  of  the  manufacturers  is  to 
produce  a  raw  mixture  which  runs  approximately  75  per  cent  carbonate  and 
the  balance  clay.  In  the  burning  of  this  mixture,  which  must  be  done  at  a 
high  temperature,  a  fused  mass  termed  clinker  is  formed.  This  consists 
largely  of  3CaO-SiO2,  2CaO -SiO2,  3CaO-Al2O3,  5CaO -3A12O?,  with  a  little 
free  lime.1  The  finely  ground  clinker,  which  is  the  Portland  cement,  is 
blue  to  gray  in  color,  and  has  a  specific  gravity  of  3  to  3.25. 

In  some  localities  argillaceous  limestones  are  found  which  approach  so 
closely  to  the  proper  composition,  that  but  little  additional  material  has 
to  be  added  to  make  a  mixture  of  the  proper  composition. 

1  Rankin  and  Wright,  Amer.  Jour.  Sci.,  Jan.,  1915. 


LIMES  AND  CALCAREOUS  CEMENTS 


193 


The  raw  materials  must  not  only  have  the  proper  composition,  but 
they  also  must  show  proper  physical  character,  extent,  and  location,  with 
respect  to  market  and  fuel  supplies.  As  regards  composition,  5  or  6  per 
cent  magnesium  carbonate  is  about  the  permissible  limit.  Chert,  flint, 
or  sand  are  also  undesirable  impurities,  and  alkalies  and  sulphates  should 
not  exceed  3  per  cent.  The  clay  used,  if  non-calcareous,  should  not  contain 
less  than  55  per  cent  silica  nor  more  than  70  per  cent,  and  the  ratio  of 
(AlaOs+FeaOs)  to  SiO2  should  be  about  1  :  3.  High  alumina  clays  are 
undesirable  because  they  raise  the  vitrification  temperature  and  quicken 
the  set  of  the  cement. 

The  following  are  analyses  of  Portland  cement  mixtures  before 
burning : l  — 

ANALYSES  OF  PORTLAND  CEMENT  MIXTURES 


SiO     ....... 

12.85 

12.92 

13.52 

1494 

AhOs 

492 

483 

656 

2  66 

Fe2Os  

1.21 

1.77 

1  10 

CaCO               .... 

7636 

7553 

75  13 

75  59 

MgCO3    

2.13 

4.34 

4.32 

464 

97.47 

99.39 

99.53 

98.93 

The  following  analyses  will  serve  to  illustrate  the  composition  of 
some  American  Portland  cements :  — 

ANALYSES  OF  CEMENTS 


SiO2 

AI203 

Fe203 

CaO 

MgO 

S03 

Empire  brand     .     .     .    > 
Sandusky  . 

22.04 
2308 

6.45 
6  16 

3.41 

290 

60.92 
62.38 

3.53 
1.21 

2.73 
1.66 

Alpha                                      ~ 

2262 

876 

266 

61  46 

292 

1  53 

Distribution  of  Lime  and  Cement  Materials  in  the  United  States. 
Limestone  for  Lime.  —  Limestones  of  suitable  composition  for 
making  lime  are  so  widely  distributed  that  no  particular  regions  or 
states  require  special  mention.2  In  the  New  England  states,  crys- 
talline limestones  are  the  chief  source  of  supply.  In  the  Appala- 
chian states,  from  New  York  to  Alabama,  there  are  many  Paleozoic 
limestones  of  high  purity,  notably  the  Trenton,  Lower  Helderberg, 
and  Carboniferous  limestones  (see  state  references).  The  same 

1  U.  S.  Geol.  Surv.,  Min.  Res.,  1907. 

2  Analyses  and  detailed  descriptions  will  be  found  in  the  areal  reports,  mentioned 
in  the  list  of  References. 


194  ECONOMIC  GEOLOGY 

series  of  rocks  are  also  of  importance  in  the  Mississippi  Valley 
states  from  Tennessee  (52)  to  Michigan  (35).  Lime  of  excellent 
quality  is  obtained  from  the  Subcarboniferous  in  Iowa  (23,  24), 
Kansas  (25),  and  Missouri  (53),  and  from  the  Cretaceous  in  Texas 
(53).  Limestones  suitable  for  lime  manufacture  are  also  found  in 
numerous  localities  in  the  Pacific  coast  states  (53). 

Hydraulic  Limes  (2) .  —  Largely  because  of  the  great  abundance 
of  natural-rock  cements,  which  are  of  superior  value,  these  materials, 
though  much  used  abroad,  are  of  no  importance  in  the  United 
States. 

It  was  stated  that  in  1906  and  1907  !  several  natural  cement 
plants  had  been  making  and  marketing  a  true  hydraulic  lime,  but 
little  or  none  is  made  now. 

Natural  Rock  Cements  (2,  43,  53).  —  Calcareous  rocks  for  making 
natural  cement  are  found  at  a  number  of  points,  the  more  impor- 
tant ones  being  given  in  summarized  form  in  the  following  table :  — 

GEOLOGIC  AGE  OF  NATURAL  CEMENT  ROCKS  IN  THE  UNITED  STATES 


STATE                             GEOLOGIC  AGE 

STATE 

GEOLOGIC  AGE 

Georgia                     Cambro-Ordivician 

Ohio 

Devonian 

Illinois                       Ordovician 

Pennsylvania 

Ordovician 

Indiana-Kentucky  Devonian 

Texas 

Cretaceous 

Kansas                       Carboniferous 

Virginia 

Cambrian 

Maryland                  Silurian 

West  Virginia- 

Minnesota                 Ordovician 

Maryland 

Cambrian 

New  York                 Silurian 

Wisconsin 

Devonian 

North  Dakota          Cretaceous 

In  many  districts  the  cement  rocks  occur  in  more  than  one 
bed,  and  may  be  interstratified  with  limestones  or  shales  of  no 
economic  value  for  cement  making  (Fig.  64). 

Some  of  the  important  occurrences  may  be  briefly  referred  to. 

New  York  (43).  —  This  state  contains  four  localities  in  which 
natural  cement  rock  is  found,  these  in  the  order  of  their  impor- 
tance being:  1.  Rosendale  District  in  Ulster  County;  2.  Akron- 
Buffalo  District  in  Erie  County;  3.  Fayetteville-Manlius  District 
in  Onondaga  County  (mostly) ;  4.  Howe's  Cave,  Schoharie  County. 
The  following  chart  shows  their  occurrence  at  different  horizons  in 
the  Silurian:  — 

1  U.  S.  Geol.  Surv.,  Min.  Res.,  1907  :  490,  1908. 


PLATE  XXII 


FIG.  1.  —  Quarry  of  natural  cement  rock,  Cumberland,  Md.     (H.  Ries,  photo.) 


FIG.  2.  —  Natural  cement  rock  quarry,  Milwaukee,  Wis.     (H.  Ries,  photo.) 

(195) 


196 


ECONOMIC  GEOLOGY 


FORMATION 

ULSTER  Co. 

SCHOHARIE 

ONONDAGA 

ERIE 

Manlius 

t 

Present,  not 
worked    for 
cement 

Worked     at 
Howe's  cave 

Worked     for 
cement       at 
Manlius,  etc 

Absent 

Rondout 

Upper      ce- 
ment bed  of 
Rondout 
district 

Worked   for 
cement      at 
Howe's  Cave 

Present,  but 
not    worked 

Absent 

Cobleskill 

Present 

Not  used  for 
cement 

Bertie 

Lower      ce- 
ment bed  of 
Rondout 
district 

Absent 

Present       in 
Onondaga 
Co.,  but 
rarely  used 

Worked 
around 
Akron  and 
Buffalo 

Wilber 

Limestones 

No  cement 

In  Rosendale  district  (Figs.  62  and  63),  two  distinct  beds  are 
worked  usually,  which  differ  in  chemical  composition  and  geologic 
age.  The  lower  or  dark  bed,  according  to  Darton,  averages  about 
21  feet,  while  the  upper  or  light  bed  is  about  11  feet,  the  two  being 
separated  by  14-15  feet  of  worthless  limestone. 

The  lower  bed  rests  directly  on  Clinton  quartzite. 

The  folding  and  faulting  are  intense  in  the  Rosendale  district 
(Fig.  63),  but  the  beds  show  little  disturbance  in  the  others. 

Other  States.  —  Southward  from  New  York  natural  cement  rock  is  quar- 
ried at  a  number  of  points  along  the  Appalachians,  but  owing  to  the  folded 
character  of  the  beds  the  extraction  is  often  difficult  (Pi.  XXil,  .big.   1). 
The  Lehigh  district  of  Pennsylvania  is  an  important  producer  of  natural 
cement,  but  still  more  so  of  Portland  cement  (p.  198). 

Several  beds  are  worked  in  the  Cumberland-Hancock  area  of  Maryland 
(32,  33),  while  in  Virginia  (55)  limestones  of  suitable  composition  for  natural 
cement  manufacture  occur  at  several  horizons,  but  only  the  argillaceous 
magnesian  limestones  found  in  the  lower  part  of  the  Shenandoah  (Cambro- 
Ordovician)  limestone  will  probably  prove  of  economic  value.  Others 
are  worked  in  Georgia  (14,  15,  53.) 

Natural  cement  has  been  made  at  Utica,  111.  (53),  from  dolomitic 
limestone  (Fig.  64),  for  nearly  fifty  years. 

Near  Milwaukee,  Wisconsin  (53),  the  cement  beds  occur  interstratified 
with  Devonian  limestone  (PI.  XXII,  Fig.  2).  Farther  west  near  Fort 


LIMES  AND  CALCAREOUS  CEMENTS 


197 


Scott,  Kansas  (25),  slightly  magnesian  Carboniferous  argillaceous  limestones, 
are  worked. 

Cement  rock  is  also  obtained  in  southeastern  Ohio  (44),  and  at  Louis- 
ville, Kentucky  (29),  probably  the  second  most  important  center  in  the 
United  States. 


FIG.  62.  —  Geologic  map  through  the  Vlightberg  at  Rondout,  N.  Y.     (After  van 
Ingen,  N.  Y.  State  Mus.,  Bull.  69.) 

Portland  Cements.  —  Clay  and  limestone,  in  one  form  or  another, 
are  so  widely  distributed  throughout  the  United  States  that  it 
is  possible  to  manufacture  Portland  cement  at  many  localities, 


198 


ECONOMIC  GEOLOGY 


C  T  W 

SECTION  111,  ALONG  DELAWARE  AVE. 


SECTION  II.,  THROUGH  NORTH  END  OF  VLIGHTBERG   / 


0      100    200   300   400  500  Feet1 


SECTION    I,  THROUGH  MIDDLE  "OF  VLIGHTBERG 


FIG.  63.  —  Geologic  sections  through  the  Vlightberg,  showing  position  of  natural 
rock  cement  beds.      (After  van  Ingen,  N.  Y.  State  Mus.,  Butt.  69.) 


Limestone 


Cement  rock 


wdstone 


7  feet 


and  the  geologic  age  of  the  materials  used  ranges  from  Ordovi- 

cian  to  Pleistocene    (53),    (Refs. 

under  different  states).     Twenty-   Cement  rock 

six     states    were     making    this 

cement   in    1914,    the    factories 

being   spread  over   the  country 

from  the  Atlantic  to  the  Pacific 

(Fig.  68). 

Pennsylvania.  — By  far  the  most 
important  district  is  the  Lehigh 
Valley  in  Pennsylvania,  which 
supplies  about  30  per  cent  of  the 
domestic  product. 

The  cement  belt  lies  in  North- 
ampton and  Lehigh  counties, 
Pennsylvania  (Fig.  65),  and  the  Cement  rock 


16-22  feet 


6  feet 


2-4  feet 


5  feet 


geologic     Section     involved    is     as     FlG.  64.  _  Section  in  cement 

follows  (50):  — 


quarries 


at  Utica,  111.     (After  Eckel.) 


LIMES  AND   CALCAREOUS  CEMENTS 


199 


200 


ECONOMIC  GEOLOGY 


Hudson  River  slate.     Probably  500  feet   thick.     No  limestone.      Sharp 
boundary. 

[More    or    less    argillaceous    slaty   limestone,     the 
Trenton  limestones.  \      cement  rock. 

[  Nearly  pure  limestones  with  some  dolomitic  beds. 

[  Kittatinny    dolomites    and    ctolomitic    limestones. 
Cambrian  j      3000' ± .    Some  beds  flinty,  and  lowest  are  siliceous. 

I  Basal  conglomerates  or  quartzite. 
Pre-Cambrian  rocks.     Mainly  gneisses. 

The  lower  member  of  the  Trenton  varies  in  its  physical  character, 
and  furnishes  material  to  raise  the  lime  content  of  the  cement  rock 
for  Portland  cement  manufacture.  Its  lime  carbonate  content  varies 
from  80  to  97  per  cent,  but  occasionally  drops  to  70  per  cent,  while  the 
magnesian  carbonate  runs  from  1.5  to  3  per  cent.  In  a  few  it  reaches 
20  per  cent,  and  these  highly  magnesian  layers  cause  trouble  in  quar- 
rying. The  upper  or  slaty  member  of  the  Trenton  grades  into  the 
lower  one.  The  rocks  of  this  region  have,  by  post-Carboniferous 
folding,  been  bent  into  a  complex  series  of  folds  (Figs.  66  and  67), 


FIG.  66. — Diagrammatic  section  two  miles  long  extending  northwest  from  Martin's 
Qreek,  N.  J.,  showing  overturned  folds.  0  and  1  =  Cambrian  dolomite;  2  and  3  = 
Lower  Trenton,  rocks  high  in  lime;  4  =  cement  rock,  Upper  Trenton,  averaging 
70  to  80  per  cent  CaCOs;  5= Upper  Trenton  cement  rock  with  less  than  70  per 
cent  CaCOs;  6  =  Hudson  River  slate.  (After  Peck,  Econ.  GeoL,  III.) 

whose  axes  trend  northeast  and  southwest,  and  while  the  folds  are 
in  many  cases  overturned,  there  is  comparatively  little  faulting. 

The  cement  rock  extends  as  a  continuous  zone  or  belt  of  varying 
width  southwest  across  Northampton  County  from  the  Delaware  to 
the  Lehigh  River  (Fig.  65),  crosses  into  Lehigh  County, 


FIG.  67. — Diagrammatic  section  five  miles  long  extending  northwest  from  Catasau- 
qua.     Numbers  same  as  in  Fig.  66.     (After  Peck,  Econ.  GeoL,  III.) 


LIMES  AND   CALCAREOUS  CEMENTS 


201 


QQ 


202  ECONOMIC   GEOLOGY 

and  ends   abruptly  at    a  point  four  and  a  half  miles  west  of 
Coplay. 

The  same  beds  are  found  in  the  adjacent  territory  of  New 
Jersey  (38). 

Other  States.  —  In  the  eastern  half  of  New  York  (43)  the  Ordovi- 
cian  and  Silurian  limestones  form  an  inexhaustible  supply  of  ma- 
terial to  mix  with  Pleistocene  surface  clays.  In  the  south  central 
part  of  New  York  the  Tully  limestone  and  Hamilton  shales  are 
employed,  while  in  the  central  and  southwestern  portion  beds  of 
bog  lime  (PL  XXIII,  Fig.  2),  associated  with  surface  clays,  are 
utilized. 

Ohio  (46,  74),  Indiana  (18-21)  and  Michigan  (34-36)  are  im- 
portant Portland  cement  producing  states.  The  abundance  of 
bog  lime  and  Pleistocene  clays  makes  them  the  favorite  materials, 
notwithstanding  the  fact  that  beds  of  Paleozoic  limestones  occur 
in  each  of  the  states.  Bog  lime,  although  especially  abundant 
in  Michigan,  is  found  in  many  states  lying  east  of  the  Mississippi 
and  north  of  the  terminal  moraine.  It  is  precipitated  from  the 
waters  of  ponds  through  the  agency  of  minute  plants,  especially 
Chara  (35). 

In  Kansas  Carboniferous  shales  and  limestones  are  used  for 
making  Portland  cement  (25,  26,  28),  and  in  Texas  and  Arkansas 
the  Cretaceous  shales  and  chalky  limestones  are  employed  (13, 
14,  53);  Alabama  has  a  Cretaceous  limestone  of  such  com- 
position that  very  little  clay  or  shale  has  to  be  added  to  it  (12). 
Portland  cement  is  also  manufactured  in  North  Dakota  (53), 
South  Dakota  (51),  Utah  (53),  Colorado  (53),  and  California 
(15,  53). 

Cement  Materials  in  Canada.  —  Portland  cement  plants  are 
scattered  over  the  Dominion  from  east  to  west.  In  Quebec 
and  Ontario  the  Paleozoic  limestones  are  used,  and  mixed  with 
shales  or  surface  clays,  but  a  number  of  the  Ontario  plants  are 
employing  bog  lime  for  the  calcareous  ingredient  of  the  cement. 
As  limestones  are  scarce  on  the  Great  Plains,  there  are  few 
cement  plants  in  this  area,  but  between  Calgary  and  the  Pacific 
Coast,  where  Paleozoic  and  Mesozoic  limestones  are,  plentiful, 
some  half  dozen  plants  have  been  established.  There  is  also  at 
least  one  in  operation  on  Vancouver  island,  which  is  using  a 
mixture  of  Cretaceous  limestone  and  a  metamorphosed  dacite 
or  andesite.1 

1  C.  H.  Clapp,  private  communication. 


PLATE  XXIII 


FIG.   1. — Limestone  quarry  in  Lehigh  cement  district,   Pennsylvania.     (H.  Ries, 

photo.) 


FIG.  2.  —  Marl  pit  at  Warners,  N.  Y.     The  dark  streaks  are  peat,  and  the  marl  is 
underlain  by  clay.     (H.  Ries,  photo.) 

(203) 


204 


ECONOMIC  GEOLOGY 


90 


LIMES  AND   CALCAREOUS   CEMENTS 


205 


Uses  of  Lime  (43,  2).  —  The  most  important  single  use  of 
lime  is  for  mixing  with  sand  to  form  mortar,  and  many  thousands 
of  tons  are  used  annually  for  this  purpose.  In  addition  to  this 
use  lime  is  employed  for  a  great  variety  of  purposes,  of  which 
the  following  are  the  most  important:  as  a  purifier  in  basic 
steel  manufacture;  in  the  manufacture  of  refractory  bricks, 
ammonium  sulphate,  soap,  bone  ash,  gas,  potassium  dichromate, 
paper,  pottery  glazes,  and  calcium  carbide;  as  a  disinfectant; 
as  a  fertilizer;  as  a  polishing  material;  for  dehydrating  alcohol, 
preserving  eggs,  and  in  tanning. 

Uses  of  Cement  (2,  5) .  —  The  use  of  hydraulic  cement  is 
constantly  increasing  in  the  United  States,  this  being  specially 
true  of  Portland  cement,  which  is  superseding  natural  cement 
to  a  great  extent,  and  is  finding  an  increasing  use  in  building 
and  engineering  operations.  For  pavements,  Portland  cement 
is  probably  more  extensively  used  in  America  than  in  any  other 
country;  and  as  an  ingredient  of  concrete  it  is  widely  employed. 
Blocks  weighing  as  much  as  65  to  70  tons  have  been  made  for 
harbor  improvements  at  New  York  City  (5) . 

The  Production  of  Cement.— The  tables  on  pp.  205-207  give  the 
production  of  natural-rock  and  Portland  cement.  Those  given 
for  the  latter  cover  a  greater  period  than  those  of  the  former, 
and  are  grouped  with  figures  of  import  and  consumption  in  order 
to  show  more  clearly  the  tremendous  growth  of  the  American 
Portland  cement  industry. 

The  diagram  (Fig.  69)  shows  most  clearly  the  remarkable 
increase  in  the  production  of  Portland  cement,  and  the  rapid 
decrease  in  the  natural  cement  production,  the  latter  being  now 
of  small  importance  in  the  cement  industry. 

The  Portland-cement  curve  shows  a  rapid  rise  after  1895,  this 
year  marking  the  introduction  of  powdered  coal  fuel  in  the  rotary 
kiln.  The  sag  in  1907  was  due  to  financial  troubles. 


PRODUCTION  OF  PUZZOLAN  CEMENT  IN  THE  UNITED  STATES,  1909-1914 


YEAR 

QUANTITY 
(BARRELS) 

VALUE 

YEAR 

QUANTITY 
(BARRELS) 

VALUE 

1909 

160,646 

$99,453 

1912. 

91,864 

$77,363 

1910.    .    .; 

95,951 

63,286 

1913.     .     . 

107,313 

97,663 

1911. 

93,230 

77,786 

1914.     .     .' 

68,311 

63,358 

206 


ECONOMIC  GEOLOGY 


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LIMES  AND   CALCAREOUS   CEMENTS 


207 


PRODUCTION  OF  PORTLAND  CEMENT  IN  THE  UNITED  STATES  IN  1914,   BY 

STATES 


STATE 

PRODUCING 
PLANTS 

QUANTITY 
(BARRELS) 

Pennsylvania 

20 

26  570  1  51 

Indiana  .     .     .     .     .     ,     .    -.     . 

5 

9  595  923 

California    .... 

7 

5  075  114 

New  York             .     .      / 

g 

5  886  124 

Illinois     ...../.-   

5 

5  401  605 

Missouri      .          .     .     , 

5 

4  723  906 

New  Jersey       

3 

3  674  800 

Michigan     

11 

4  285  345 

Iowa  .....'.. 

3 

4  233  707 

Kansas    .     .     .     ...     .     .     .     .     .     .     . 
Washington      

9 
5 

3,431,142 
2  017  344 

Texas 

4 

2  100  341 

Ohio   

5 

1  962  047 

Utah  

3 

981  100 

Other  states  l  ,.    -. 

17 

8  291  521 

Total    .  -  .     .     .     .     .     .     .     .     .     .  "  . 

110 

88,230  170 

Includes  Alabama,  Arizona,  Colorado.  Georgia,  Kentucky,  Maryland,  Mon- 
tana, Oklahoma,  Tennessee,  Virginia,  West  Virginia  and  Nebraska. 

PRODUCTION,  EXPORTS,  AND  IMPORTS  OF  PORTLAND  CEMENT  IN   CANADA, 

1912-1913 


1912 

1913 

BARRELS 

VALUE 

BARRELS 

VALUE 

Production  . 
Imports  .     .     .     . 
Exports  .     .     .     . 

7,132,732 

1,434,413 

$9,106,556 
1,969,529 
2,436 

8,658,805 
254,093 

$11,019,418 
409,303 
1,739 

REFERENCES    ON    LIME    AND    CEMENT    MATERIALS 

TECHNOLOGY.  1.  Cummings,  American  Cements,  Boston,  1898.  (Many 
analyses.)  2.  Eckel,  Cements,  Limes  and  Plasters,  New  York,  1907. 
(Wiley  &  Sons.)  3.  Burchard  and  Emley,  U.  S.  Geol.  Surv.,  Min. 
Res.,  1913:  1509,  1914.  (Properties,  uses  and  manufacture  of  lime.) 
4.  Humphrey,  U.  S.  Geol.  Surv.,  Bulls.  331  and  344.  (Tests  of  cement 
mortars  and  concrete.)  5.  Eno,  Ohio  Geol.  Surv.,  4th  ser.,  Bull.  2, 
1904.  (Uses  of  hydraulic  cements.)  6.  Bleininger,  Ohio  Geol.  Surv., 
4th  ser.,  Bull.  3,  1904.  (Manufacture  of  hydraulic  cements.) 

LOCALITY  REPORTS.  Alabama:  7.  Meissner,  Ala.  Ind.  and  Sci.  Soc.,  Proc., 
IV:  12.  (Birmingham  district  limestone.)  8.  Smith,  Ala.  Geol. 


208  ECONOMIC   GEOLOGY 

Surv.,  Bull.  8,  1904.  (Many  analyses.) — Arkansas:  9.  Branner, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XXVII:  42,  1898.  (S.  W.  Ark.) 
10.  Taff,  U.  S.  Geol.  Surv.,  22d  Ann.  Kept.,  Ill:  687,  1902.  (S.  W. 
Ark.)  —  California:  11.  Grimsley,  Eng.  and  Min.  Jour.,  LXXII:  71, 
1901.  (Cement  industry.)  12.  Irelan,  8th  Ann.  Kept.,  State  Miner- 
alogist: 865  to  838,  1888;  also  9th  Ann.  Kept:  309-311,  1889;  13th 
Ann.  Kept.  Calif.  State  Mineralogist:  627,  1896;  12th  Ann.  Kept.: 
381,  1894.  (Cements.)  Anon.,  Calif.  State  Min.  Bureau,  Bull.  38. 

—  Colorado:   12a.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  522,  1913. — Florida: 
13.  Fla.  Geol.  Surv.,  1st  Ann.  Kept.:  40,  1908.  —  Georgia:  14.  Maynard, 
Ga.   Geol.   Surv.,   Bull.   27,    1912.     15.  Cummings,   U.   S.   Geol.   Surv., 
21st  Ann.   Kept.,  VI:    410,    1901.  —  Illinois:     16.  Eckel,   U.   S.   Geol. 
Surv.,  Bull.  522,   1913.     17.  Bleininger,  Lines  and  Layman,  111.  Geol. 
Surv.,  Bull.  17,  1912.       Indiana:    18.  Blatchley,  25th  Ann.  Kept.  Ind. 
Dept.   Geol.   and  Nat.   Res.,    1900:    323,    1901.     (Bedford  limestone.) 
19.  Siebenthal,  25th  Ann.  Kept.  Ind.  Dept.  Geol.  and  Nat.  Res.,  1900: 
331,    1901.     (Silver  Creek  hydraulic  limestone.)     20.  Blatchley,   Ibid., 
28th   Ann.    Kept.:     211,    1903.     (Lime    industry.)     21.  Blatchley   and 
Ashley,  Ibid.,  25th  Ann.  Kept.:    31,   1901.     (Marl  deposits.)  —  Iowa: 
22.  Bain    and   Eckel,    la.     Geol.    Surv.,    XV:     33.     23.  Williams,    la. 
Geol.    Surv.,    XVII:     1907.     (Tests    of   Iowa   limes.)     24.  Beyer   and 
Williams,  Ibid.,  XVII:   29,  1907.     (General.)  —  Kansas:   25.  Haworth, 
Kas.  Geol.  Surv.,  Ill:    31,  1898.     26.  Adams  and  others,  U.  S.  Geol. 
Surv.,   Bull.   238,    1904.     (lola  Quadrangle.)     27.  Annual  bulletins  on 
Mineral  Resources,  issued  by  Kansas  Geological  Survey.     28.  Haworth 
and  Schrader,  U.  S.  Geol.  Surv.,  Bull.  260:   506,1905.     (Independence 
Quadrangle.) — Kentucky:     29.  Kentucky    Geol.    Surv.,    New    Series, 
IV:    404.     30.  Eckel,   U.   S.    Geol.   Surv.,   Bull.   243:     171.  — Maine: 
31.  Bastin,  U.  S.  Geol.  Surv.,  Bull.  285:    393,  1906.     (Knox  County.) 

—  Maryland:    32.  Clark  and  others,  Md.  Geol.  Surv.,  Rept.  on  Alle- 
gany  Co.:    185,   1900.     (Lime  and  cements.)     33.  Martin,   Md.  Geol. 
Surv.,  Rept.  on  Garrett  Co.:    220,  1902.     33a,  Mathews  and  Grasty, 
Md.  Geol.  Surv.,  VIII:    Pt.  3:    225,  1910.  —  Michigan:    34.  Hale  and 
others,    Mich.    Geol.    Surv.,   VIII,    Pt.    3,    1903.     (Marl   for   Portland 
cement.)     35.  Lane,  Eng.  and  Min.  Jour.,  LXXI:    662,  693,  and  725, 
1901.     (Mich,    limestones.)     36.  Russell,  U.  S.  Geol.  Surv.,  22d  Ann. 
Rept.,  Ill:    629,  1902.     (Mich.  Portland  cement  industry.)  —  Missis- 
sippi:   37.  Crider,  Miss.  Geol.  Surv.,  Bull.  1,  1907.     (N.  E.  Miss.)  - 
Missouri:     37a.    Buehler,    Mo.    Geol.    Surv.,     2d    Ser.    VI.     1907.- 
New  Jersey:    38.  Kummel,  Ann.  Rept,  N.  J.  State  Geologist,   1900: 
9.     (N.    J.    Portland    cement    industry.)     39,  Kummel,    N.    J.    Geol. 
Surv.,  Ann.  Rept.,  1905:    173,  1906.     (Limestones,  Sussex  and  Warren 
counties.)  —  New  York:    40.  Bishop,    15th  Ann.   Rept.   N.   Y.   State 
Geologist:    338,  1897.     (Erie  Co.)     41.  Nason,  Rept.  of  N    Y.  State 
Geologist,  1893:    375.     (Ulster  Co.)     42.  Pohlman,  Amer.  Inst.   Min. 
Engrs.,   Trans.   XVIII:    250,    1889.     (Cement  rock   at   Buffalo.)     43. 
Ries  and  Eckel,  Bull.  N.  Y.  State  Museum,  44,   1901.     (N.  Y.  lime 
and  cement  industry.)  —  Ohio:    44.  Lord,  Ohio  Geol.  Surv.,  VI:    671, 
1888.     (Natural  and  artificial  cements.)     45.  Eno,  Ohio  Geol.  Surv., 


LIMES  AND   CALCAREOUS   CEMENTS  209 

4th  Series,  Bull.  2,  1904.  (Uses  of  cement.)  46.  Bleininger,  Ibid., 
Bull.  3,  1904.  (Manufacture  of  cement.)  47.  Orton  and  Peppel,  Ibid., 
Bulls.  4  and  5,  1906.  (Limestones.)  —  Oklahoma:  47a  Okla.  Geol. 
Surv.,  Bull.  5:  114,  1911.  —  Oregon:  476.  Williams,  Min.  Res.  Ore., 
I,  No.  7:  52,  1914.  —  Pennsylvania:  48.  Prime,  Second  Geol.  Surv. 
of  Pa.,  Rep.  DD:  59,  1878.  49.  Clapp,  U.  S.  Geol.  Surv.,  Bull.  249, 

1905.  (Limestones,  S.  W.  Pa.)     50.  Peck,  Econ.  Geol.  III.:   37,  1908. 
(Lehigh  district.)    50a.  Hice,  Pa.  Top.  and  Geol.  Com.,  Rept.  9:  71, 1913. 
—  South  Dakota:    51.  S.  Dak.  Sch.    of  Mines,  Bull.  8,  1908.     (Black 
Hills.)— Tennessee:    52.  Eckel,   U.  S.   Geol.    Surv.,   Bull.  285:    374, 

1906.  (Tenn.-Va.)     52a.  Gordon,    Res.    Tenn.,    I,    No.    2.       United 
States:    53.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  522,  1913.     (Details  on  all 
states.)— Virginia:    54.  Catlett,   U.   S.   Geol.   Surv.,   Bull.   225:    457, 

1904.  (Cement  resources,  Valley  of  Va.)     55.  Bassler,   Min.  Res.  of 
Va.,   Lynchburg,    1907,    p.   86.     55a.  Bassler,   Va.    Geol.    Surv.,    Bull. 
II-A,  1909. —  Washington:    56.  Landes,  U.  S.  Geol.  Surv.,  Bull.  285: 
377,   1906. —  West  Virginia:    57.  Grimsley,  W.  Va.  Geol.  Surv.,  Ill, 

1905.  —  Wisconsin:    58.  Chamberlin,    Geol.  of  Wis.,  II,  Pt.  2:    395, 
1873.     (Natural  rock  cement.)     Buckley,  Wis.  Geol.  and  Nat.  Hist. 
Surv.,  Bull.  4:    255,  1898.  —  Wyoming:    59.  Ball,  U.  S.  Geol.  Surv., 
Bull.  315:  232,  1907,     (E.  Wyo.) 


CHAPTER  VI 
SALINES  AND    ASSOCIATED    SUBSTANCES 

UNDER  the  heading  of  salines  are  included  the  substances, 
salt,  borax,  sodium  sulphate,  sodium  carbonate,  sodium  and 
potassium  nitrate.  They  are  all  easily  soluble  substances,  which 
are  either  found  dissolved  in  the  waters  of  lakes,  seas  or  oceans,  or 
may  be  present  at  times  in  the  rocks  or  soils.  As  a  result  of  the 
leaching  of  the  last-named  by  underground  waters,  they  may  be 
brought  to  the  surface  and  deposited  there  as  an  incrustation, 
often  found  in  arid  regions;  or  they  may  be  carried  into  bodies 
of  water,  where  they  remain  in  solution  until  the  waters  by 
evaporation  leave  them  behind  as  residues.  Either  mode  of 
deposition  would  be  characteristic  of  an  arid  climate. 

The  above  outlines  in  general  their  manner  of  formation, 
although  there  may  be  exceptions,  as  will  be  seen  in  subsequent 
pages. 

Bromine,  calcium  chloride,  and  iodine  are  also  treated  in  this 
chapter,  because  of  the  association  of  the  first  two  with  sodium 
chloride,  and  of  the  third  with  sodium  nitrate. 

From  what  has  been  said  above,  it  will  be  readily  seen  that 
bodies  of  saline  water  may  not  only  vary  in  their  degree  of  con- 
centration, but  also  in  the  kind  and  relative  amounts  of  the  dif- 
ferent saline  substances  which  they  contain  in  solution. 

The  analyses  on  p.  211  will  show  this  variation. 

SALT 

Types  of  Occurrence.  —  Common  salt,  the  chloride  of  sodium 
(NaCl),  is  a  widely  distributed  mineral,  being  found:  (1)  in  solu- 
tion in  sea  water  or  salt  lakes;  (2)  as  solid  masses  termed  rock 
salt;  (3)  as  natural  brine  in  cavities  or  pores  of  the  rocks,  from 
which  it  may  exude  as  salt  springs  or  be  tapped  by  wells;  ard  (4) 
in  marshes  and  soils. 

Although  all  four  of  these  types  of  occurrence  may  serve  as 
commercial  sources  of  salt,  it  is  only  the  second  that  is  of  great 
economic  importance. 

210 


SALINES  AND  ASSOCIATED  SUBSTANCES 
ANALYSES  OF  LAKE  AND  SEA  WATERS 


211 


I 

II 

III 

IV 

V 

VI 

VII 

VIII 

IX 

Cl   . 

55.292 

55.69 

70.25 

67.66 

42.04 

53.32 

3.18 

23.34 

32.27 

Br  . 

.188 

tr. 

1.55 

1.98 

.05 

.06 



.04 

SO4 

7.692 

6.52 

.21 

.22 

23.99 

17.39 

7.47 

12.86 

.13 

COs 

.207 



tr. 

tr. 

.37 



38.73 

23.42 

22.47 

Na. 

30.593 

32.92 

6.33 

10.20 

24.70 

11.51 

10.10 

37.93 

38.10 

K    . 

1.106 

1.70 

1.70 

1.62 

.54 

1.83 

4.56 

1.85 

1.52 

Ca  . 

1.197 

1.05 

5.54 

1.51 

2.29 



12.86 

.04 

.03 

Mg 

3.725 

2.10 

14.42 

16.81 

5.97 

15.83 

4.15 

.10 

.35 

Si02 





tr. 

tr. 



.  

18.95 

.14 

.01 

PO4 



.  











.  

.02 

B4O7 















.32 

5.05 

Salinity 

.3.301  i 

23.0361 

20  .  709  ] 

24.573' 

1.2941 

28.501 

.732 

51,1702 

76,560  « 

1  Salinity  per  cent. 


Salinity  parts  per  million. 


I.  Mean  of  77  analyses  of  sea  water.  II.  Great  Salt  Lake,  the  same 
type  as  ocean  water,  but  having  no  carbonates,  higher  sodium,  and  lower 
magnesium.  III.  Dead  Sea  water  from  depth  of  20  meters.  IV.  The  same, 
depth  of  120  meters.  This  lake  derives  its  chlorides  and  sulphates  from 
leaching  of  surrounding  deposits  containing  salt  and  gypsum,  but  carbon- 
ates and  gypsum  are  deposited  when  the  Jordan,  its  main  feeder,  enters  the 
lake,  hence  the  dissolved  substances  are  largely  chloride.  V.  Caspian 
Sea.  VI.  Karaboghaz  Gulf.  Note  the  quantity  of  Mg  and  SO4. 
VII.  Lake  Tahoe,  Calif.  VIII.  Mono  Lake,  Calif.  This  yields  trona 
(Na2CO3-HNaCO3-2H2O),  on  evaporation,  and  is  typical  of  lakes  occupying 
closed  basins,  in  regions  of  great  volcanic  activity,  the  products  of  eruption 
having  been  leached,  and  the  waters  showing  an  abundance  of  sulphate 
and  carbonates  of  sodium,  as  well  as  some  chloride.  Waters  of  this  type  may 
on  evaporation  also  yield  glauber's  salt,  borates  and  perhaps  even  nitrates. 
IX.  Borax  Lake,  Calif.  This  is  said  to  derive  its  boron  from  hot  springs. 
Analyses  I-IX  from  Clarke,  United  States  Geological  Survey,  Bulletin 
616,  1916. 

Occurrences  of  Salt  in  Sea  and  Lake  Waters.  —  Salt  is  pres- 
ent in  all  ocean  water,  and  also  in  that  of  most  inland  lakes  or  seas 
having  no  outlet,  as  can  be  seen  from  the  analyses  in  the  preceding 
table. 

Salt  is  sometimes  obtained  by  artificial  evaporation  of  the 
water  of  either  the  ocean  or  salt  lakes;  but  in  the  United  States 
this  plan  is  profitable  only  under  exceptional  conditions,  as  around 
San  Francisco  Bay,  California  (8),  or  Great  Salt  Lake,  Utah  (21). 

Natural  Brines.  —  These,  sometimes  found  in  porous  layers 
of  the  rocks,  may  result  either  from  sea  water  imprisoned  in  the 
layers  of  sediment  or  from  the  solution  of  rock  salt  by  percolating 
waters. 

Salt  Marshes  and  Soils.  —  When  away  from  the  ocean,  these 
owe  their  salinity  to  the  infiltration  of  brine  from  neighboring 


212  ECONOMIC  GEOLOGY 

saliferous  formations.  They  sometimes  represent  the  site  of 
former  salt  lakes. 

Rock  Salt.  —  Rock  salt,  which  is  the  most  important  source 
of  commercial  salt,  occurs  commonly  in  beds  of  variable  thickness 
and  purity  interbedded  with  sedimentary  rocks,  such  as  shales  or 
sandstones.  It  is  frequently  associated  with  gypsum,  and  less 
commonly  with  limestone,  or  easily  soluble  compounds  of  magnesia, 
potash,  and  lime.  Less  often,  the  rock  salt  is  found  in  domelike 
masses  in  stratified  rocks,  but  not  conformable  with  them.  Rock 
salt  deposits  vary  in  thickness  from  a  few  inches  up  to  as  much  as 
3600  feet  (Sperenberg,  Germany);  and  while  found  in  all  geo- 
logical formations  from  the  Cambrian  to  the  Pleistocene,  except 
the  Cretaceous,  the  rock  salt  of  the  United  States  is  not  found  in 
formations  older  than  the  Upper  Silurian. 

Origin  of  Rock  Salt  (l-7a).  —  One  of  the  interesting  problems 
of  geology  has  been  to  find  a  correct  theory  to  account  for  the 
origin  of  salt  deposits.  Such  a  problem  is  not  as  simple  as  it 
may  appear  at  first  sight,  for  it  must  explain  (1)  the  formation 
of  salt  deposits  of  extraordinary  thickness,  (2)  the  association  of 
gypsum,  either  above  or  below  the  salt,  and  (3)  the  presence  of 
other  minerals,  which  may  or  may  not  be  saline  ones. 

Evaporation  Theory. — It  is  generally  believed  that  most  de- 
posits of  rock  salt,  or  of  rock  salt  and  gypsum,  have  been  formed 
by  the  evaporation  of  oceans  and  lakes,  this  process  having 
gone  on  during  a  number  of  periods  from  the  Silurian  to  the 
present. 

If  a  body  of  salt  water  is  evaporated  until  precipitation  begins, 
the  least  soluble  salts  will  generally  separate  out  first,  while  the 
most  soluble  ones  do  not  precipitate  until  the  last. 

Assuming  then  a  basin  filled  with  sea  water,  similar  in  com- 
position to  that  of  the  present  oceans,  the  order  of  precipita- 
tion would  be:  (1)  iron  hydroxide;  (2)  calcium  carbonate;  (3) 
calcium  sulphate;  (4)  sodium  chloride;  and  (5)  easily  soluble 
compounds,  such  as  sulphates  and  chlorides  of  potash  and  mag- 
nesia, etc.,  these  being  often  of  quite  complex  composition. 

This  order  of  precipitation  was  demonstrated  as  early  as 
1849,  by  J.  Usiglio,1  who  made  an  elaborate  series  of  evaporation 
tests  of  Mediterranean  water. 

The  four  following  analyses,  reduced  to  ionic  form  and  to 

1  Ann.  chim.  phys.,  3d.  ser.,  XXVII:   92,  192,  1849. 


SALINES  AND  ASSOCIATED  SUBSTANCES 


213 


percentages   of   total  solids,  represent   the   composition   of   the 
sea  water  evaporated  to  different  densities.1 

ANALYSES  OF  MEDITERRANEAN  WATER  AND  BITTERNS 


CONSTITUENTS 

A 

B 

c 

D 

Cl     .    .    .    .     : 

54  39 

56  18 

49  99 

4Q  13 

Br 

1  15 

1  22 

2  68 

3f)Q 

SO4  .     .     .     .     . 

7.72 

5.78 

14  64 

17  3fi 

CO3  

18 

Na 

31  08 

32  06 

20  39 

12  8Q 

K      

.71 

78 

2  25 

3  SI 

Ca    .     .     . 
Me  . 

1.18 
3.59 

.26 

3  72 

10  05 

14  28 

i.V-1^ 

Salinity      .     .     . 

3.766 

27.546' 

33.712 

39.619 

A.  The  water  itself,  density  1.0258.  B.  Bittern  of  density  1.21.  C. 
Bittern  of  density  1.264.  D.  Bittern  of  density  1.32. 

Clarke  considers  that  the  bromine  determinations  are  excessive, 
and  that  the  potash  is  too  low.  However,  the  analyses  show: 
(1)  the  elimination  of  calcium  as  carbonate,  and  later  as  sul- 
phate: (2)  the  subsequent  deposition  of  sodium  chloride,  and 
(3)  the  still  later  accumulation  of  the  more  soluble  substances  in 
the  mother  liquors. 

Simple  as  the  phenomena  of  concentration  of  sea  water  would 
appear,  they  may  yet  be  complex,  and  it  is  possible  as  well  as 
probable  that  the  order  of  precipitation  is  not  always  in  the  order 
of  solubility,  this  being  governed  to  some  extent  at  least  by  other 
salts  present,  degree  of  concentration  and  temperature. 

The  Stassfurt  Section. — There  are  few  salt  deposits  in  the  world 
that  show  such  a  complete  series  of  precipitates  as  Usiglio  ob7 
tained  in  his  experiments,  and  the  most  nearly  perfect  one  is  that 
found  at  Stassfurt,  in  Prussia,  where  more  than  thirty  saline 
minerals  are  known  to  occur. 

The  section  which  occurs  in  strata  of  Upper  Permian  age  is 
;as  follows:1 

1.  Lower  Buntsandstein  (capping  rock) 

2.  Red  clay  and  concretions  of  anhydrite  and  salt  cavities        20  m. 

3.  Anhydrite  Layer  (No.  IV)    .     .     .   ' ..    .     .     .   ^   '.  .;.          4m. 

1  Quoted  by  F.  W.  Clarke,  U.  S.  G.  S.,  Bull.  616:    219. 

2  Grabau,  Principles  of  Stratigraphy,  p.  371,  quoted  from  Walther. 


214  ECONOMIC  GEOLOGY 

4.  Rock  salt 40  m. 

5.  Anhydrite  No.  Ill  (Pegmatite  anhydrite)      ....  5m. 

6.  Red  clay 10  m. 

7.  Younger  rock  salt,  with  about  400  annual  rings  of 

polyhalite       80  m. 

8.  Main  anhydrite,  No.  II 30-80  m. 

9.  Salt  clay,  averaging 5-10  m. 

10.  Carnallite  (KC1,  MgCl26H2O)  zone 15-40  m. 

11.  Kieserite  (MgSO4,  H2O)       18  m. 

12.  Polyhalite  (K2SO4,  MgSO4,  2CaSO4,  2H2O)  zone      .  35  m. 

13.  Older  rock  salt  with  about  3000  annual  rings  averaging      245  m. 

Nos.  11,  12,  13  have  a  combined  thickness,  ranging  from  150  to  perhaps 
1000  meters.  (Due  perhaps  to  subsequent  thickening.)  The  annual  rings 
of  anhydrite  form  layers  averaging  7  mm.  thick,  separating  the_salt  into  sheets 
of  8  or  9  mm. 

14.  Older  anhydrite  (I)  and  gypsum,  averaging    .     .     .          100  m. 

15.  Zechstein  limestone  or  dolomite 

16.  Copper  slates 

17.  Zechstein  conglomerate 

The  lower  members,  beginning  with  anhydrite  I  and  ending  with  the 
carnallite  zone,  form  one  depositional  series.  Above  this,  and  separated 
from  it  by  a  clay  member,  is  a  second  series,  which  lacks  the  more  soluble 
salts. 

Assuming  then  that  the  evaporation  of  a  body  of  sea  water 
may  give  a  graded  series  as  shown  above,  we  must  in  order  to  apply 
it  consider  the  following:  (1)  The  most  soluble  salts  are  often 
wanting;  (2)  salt  and  gypsum  may  occur  singly;  and  (3)  many 
salt  and  gypsum  deposits  exhibit  great  thickness. 

The  absence  of  the  mother-liquor  salts  may  be  explained  by 
assuming  that  the  water  never  was  sufficiently  concentrated  to 
cause  their  precipitation,  or  if  this  did  occur  they  may  have  been 
redissolved,  before  a  protective  covering,  such  as  a  clay  sediment, 
was  deposited  on  them. 

It  is  not  difficult  to  conceive  that  evaporation  went  on  far 
enough  to  deposit  gypsum,  and  not  enough  to  precipitate  salt, 
but  it  is  more  difficult  to  explain  why  salt  was  sometimes  deposited, 
without  any  gypsum  under  it,  unless  we  assume  that  some  of 
the  earlier  oceans  were  of  a  different  composition  than  existing 
ones. 

The  most  difficult  problem,  however,  is  to  explain  the  for- 
mation of  very  thick  deposits  of  salt  between  stratified  rocks,  on 
the  basis  of  simple  evaporation  of  a  body  of  water. 


SALINES  AND  ASSOCIATED  SUBSTANCES  215 

We  can  easily  understand  the  formation  of  a  thin  bed  of  salt 
(or  gypsum)  in  this  way,  but  the  insufficiency  of  this  explanation 
appears,  when  we  find  .that  the  formation  of  15  feet  of  gypsum 
would  require  the  evaporation  of  35,000  feet  of  existing  ocean 
water,  and  since  salt  is  more  soluble,  a  much  greater  depth  would 
be  required. 

Bar  Theory.  —  This  theory,  which  seeks  to  explain  the  origin 
of  salt  deposits  of  great  thickness,  was  first  suggested  by  G. 
Bischof,1  and  later  elaborated  by  Ochsenius  (l,  4).  It  assumes 
a  barrier  partly  shutting  out  the  ocean  water.  Evaporation  on 
the  inclosed  area  of  the  sea  exceeds  the  supply  of  water  from 
inflowing  rivers  and  from  the  open  ocean.  Therefore  the  water 
on  the  surface  of  the  sea  becomes  more  dense  and  settles  to  the 
bottom  of  the  basin,  being  prevented  from  escape  into  the  open 
ocean  by  the  barriers  at  the  entrance.  As  the  surface  of  the 
bay  is  lowered  by  evaporation,  ocean  waters  enter,  furnishing  a 
constant  supply  of  salt.  If  the  barrier  is  complete,  forming  a 
bar,  sea  water  may  enter  only  at  times  of  high  tide  or  storm. 
Eventually  evaporation  will  so  concentrate  the  solution  in  the 
bay  as  to  cause  the  precipitation  of  sodium  chloride  and  other 
salts.  So  long  as  these  conditions  lasted,  salt  would  be  pre- 
cipitated, but  beds  of  clayey  material  would  be  deposited  wherever 
fine-grained  sediment  was  supplied  from  the  land. 

This  theory  has  appealed  to  many,  and  the  case  of  Karabo- 
ghaz  Gulf  on  the  eastern  side  of  the  Caspian  Sea,  is  often  quoted 
as  illustrative  of  the  deposition  of  salts  according  to  the  hypoth- 
esis mentioned  above.  The  Gulf  referred  to  is  connected  with 
the  sea  by  a  shallow  channel  through  which  it  is  continually 
supplied  by  water,  the  latter  delivering  a  daily  estimated  load 
of  350,000  tons  of  dissolved  salts. 

Analyses  V  and  VI,  p.  211,  show  the  composition  of  the  waters 
of  the  sea  and  the  gulf  respectively. 

The  Karaboghaz  water  contains  285  parts  per  million  of  salts, 
while  gypsum  will  precipitate  when  the  concentration  is  202 
parts  per  million.  It  is  a  sulphate  chloride  bittern,  in  which 
magnesium  replaces  lime.  We  find,  then,  that  while  some  gypsum 
is  deposited  around  the  margins,  the  bottom  is  covered  by  mag- 
nesium sulphate,  which  in  places  is  7  feet  thick,  the  total  deposit 
being  estimated  at  1,000,000,000  tons.  The  salinity,  although 

1  Allgemeine  Chemische  u.  Physikalische  Geologie,  II:  48,  1864. 


216  ECONOMIC  GEOLOGY 

increasing,  is  not  yet  sufficient  to  precipitate  salt,  but  the  water 
is  sufficiently  saline  to  prevent  marine  life,  so  that  any  animals 
carried  into  the  gulf  die. 

Of  more  interest  are  the  Suez  Bittern  Lakes,  which  were 
formerly  a  continuation  of  the  present  Gulf  of  Suez,  and  the 
Red  Sea. 

When  the  gulf  became  silted  up  to  such  an  extent  that  the 
supply  of  water  from  the  Red  Sea  just  balanced  the  evaporation 
from  the  surrounding  surface  of  the  Gulf,  and  the  salinity  was 
of  corresponding  magnitude,  salt  began  to  deposit  and  continued 
until  some  time  after  the  complete  separation  from  the  Gulf 
of  Suez  and  transformation  into  the  Bittern  Lakes.  When  the 
Suez  Canal  was  cut,  a  salt  mass  13  km.  long,  7  km.  broad,  and 
averaging  8  meters  in  thickness  was  found.  It  showed  parallel 
layers  separated  by  thin  layers  of  earthy  matter  and  gypsum. 

The  operation  of  the  bar  theory  is  probably  restricted  to 
arid  regions,  where  there  will  be  little  inflow  of  fresh  water  into 
the  bay,  and  where  evaporation  will  be  accelerated. 

Grabau  points  out  that:  (1)  the  bay  must  be  connected 
with  a  large  sea;  (2)  that  there  should  be  a  contemporaneous 
fossiliferous  series  in  the  sea;  and  (3)  that  the  salt  deposits 
themselves,  as  shown  by  Karaboghaz  and  Bittern  Lakes,  should 
be  fossiliferous.  If  these  criteria  fail,  he  believes  that  the  de- 
posit could  not  have  been  formed  by  the  evaporation  of  sea 
water. 

More  recently  Branson  (la)  has  suggested  a  modified  bar 
theory,  which  postulates  overflow  basins  connected  with  a  main 
one,  the  precipitation  of  the  salts  taking  place  in  the  former. 

Desert  Theory.— This  theory  has  been  specially  urged  by  Wal- 
ther,  who  saw  the  objections  to  the  bar  theory  mentioned  above. 
According  to  the  desert  theory,  extensive  salt  deposits  might  be 
formed  by  the  leaching  of  the  salt  from  an  older  more  or  less 
saliferous  formation.  This  salt  might  be  contained  in  connate 
waters  or  in  the  rocks.  If  brought  to  the  surface  either  by  evap- 
oration or  erosion,  it  may  perhaps  first  form  a  crust  there,  and  be 
later  removed  by  wind  or  rain.  If  in  a  drainless  basin,  it  may 
accumulate  in  a  body  of  water  within  the  depression.  As  the 
water  evaporates,  and  leaves  any  of  the  salt  on  the  drainage 
slopes,  it  may  still  be  washed  down  into  the  contracting  sea  or 
lake,  whose  salinity  gradually  increases  to  such  an  extent  that 
the  salt  begins  to  deposit. 


SALINES  AND  ASSOCIATED  SUBSTANCES 


217 


Grabau  l  thinks  that  the  Siluric  salt  of  North  America  has 
been  derived  from  connate  waters  of  the  Niagara  formation,  of 
which  a  vast  amount  has  been  eroded,  for  he  says,  "  the  fact 
that  all  around  the  Salina  area,  the  Upper  Siluric  strata  rest  on 
Niagaran  except  where  the  continental  deposits  of  Salina  time 
intervene,  and  the  further  fact  that  no  undoubted  marine  equiv- 
alents of  the  Salinan  are  known  in  North  America,  greatly 
strengthen  the  argument  for  the  wholly  continental  origin  of 
these  salt  deposits." 


FIG.  70.  —  Figures  representing  the  origin  of  dome  structure  by  crystalline  growth. 
(After  Harris,  Econ.  Geol.  IV.) 

Dome  Theory  (Fig.  70).  —  In  Louisiana  and  Texas  as  well  as 
some  other  localities,  there  are  found  great  domelike  masses  of 
rock  salt,  accompanied  at  times  by  gypsum,  limestone,  and  even 
sulphur.  G.  D.  Harris  (6)  believes  they  have  been  formed  as  fol- 
lows: Heated  waters  coming  up  through  underlying  formations 
have  become  saturated  with  salt  from  deposits  occurring  in  them. 
These  waters  found  a  pathway  in  fissures  related  to  the  differential 
uplifting  of  the  rocks  in  the  Mississippi  embayment,  and  marking 
the  position  of  anticlines.  Cooling  of  the  uprising  solutions  caused 
them  to  deposit  the  salt  in  these  fissures.  It  is  thought  that  the 
force  exerted  by  the  crystallizing  salt  was  sufficient  to  lift  up  the 
overlying  Tertiary  and  Quaternary  beds,  as  the  accumulation 
went  on.2  These  cores  of  salt  have  been  pushed  up  through  Cre- 
taceous, Eocene,  and  even  Quaternary  strata. 

R.  T.  Hill  likewise  thought  the  salt  domes  due  to  deposition 
by  ascending  solutions,  but  that  the  upraising  of  the  surrounding 
strata  was  caused  by  the  hydrostatic  pressure  of  the  salt  solu- 

1  Principles  of  Stratigraphy,  p.  376. 

2  See  Day  and  Becker,  Wash.  Acad.  Sci.  Proc.,  Vol.  7:    288,  1905. 


218 


ECONOMIC   GEOLOGY 


tions  and  to  oil  rising  through  the  fractures  in  the  rocks.  On 
the  other  hand,  Hager  and  Veatch  suggested  laccolithic  intrusions 
as  the  cause  of  the  uplift,  and  recently  it  is  claimed  that  a  hard 
rock,  possibly  of  igneous  origin,  has  been  struck  by  the  drill 
below  one  of  these  domes. 

Distribution  of  Salt  in  the  United  States.  —  Salt  deposits  are  found 
in  a  number  of  states,  as  shown  on  the  map,  Fig.  71,  but  nearly 


FIG.  71. —  Map  showing  distribution  of  salt-producing  areas  in  United  States,  com- 
piled from  various  geological  survey  reports. 

63  per  cent  of  the  production  in  1914  came*  from  two  states,  New 
York  and  Michigan.  Most  of  the  domestic  production  is  obtained 
either  in  the  form  of  artificial  brine  obtained  by  forcing  water 
through  wells  to  the  salt,  which  is  then  brought  up  in  solution,  or  else 
as  rock  salt,  raised  through  shafts  from  underground  workings. 

The  range  of  geologic  age  of  the  United  States  deposits  is  shown 
in  the  following  table:  — 

TABLE  SHOWING  GEOLOGIC  DISTRIBUTION  OF  SALT  IN  THE  UNITED  STATES 


STATE 

AGE 

STATE 

AGE 

California 

Present 

Oklahoma 

Permian  (?) 

Kansas 
Louisiana 

Permian 
Tertiary 

Pennsylvania 
Texas 

Carboniferous 
Cretaceous 

Michigan 

Silurian 

Utah 

Recent 

New  York 

Mississippian 
Silurian 

Virginia 
West  Virginia 

Mississippian 
Middle  Carboniferous 

Ohio 

Silurian 

(Pottsville) 

Mississippian 

PLATE  XXIV 


FIG.  1.  —  Interior  view  of  salt  mine,  Livonia,  N.  Y.     Both  roof  and  pillar  are  rock 

salt. 


FIG.  2.  —  Borax  mine  near  Daggett,  Cal.     (Photo,  loaned  by  G.  P.  Merrill.) 

(219) 


220  ECONOMIC  GEOLOGY 

New  York  (15).  —  Salt  was  manufactured  from  brine  springs  at 
Onondaga  Lake  as  early  as  in  1788;  but  the  presence  of  rock  salt 
beds  was  not  suspected  until  1878,  when  a  bed  seventy  feet  thick 
was  struck  in  drilling  for  petroleum  in  Wyoming  County.  Since 
then  the  development  of  the  salt  industry  has  been  so  rapid  that 
for  some  years  New  York  has  been  one  of  the  two  leading  salt- 
producing  states. 

The  salt  occurs  in  lenticular  masses  interbedded  with  soft  shales 
of  the  Salina  series  (Fig.  72),  which  also  carry  gypsum  deposits. 
The  outcrop  of  the  formation  coincides  approximately  with  the 
line  of  the  New  York  Central  Railroad,  but  owing  to  its  soluble 
character,  no  salt  is  found  along  the  outcrops.  The  beds  dip  south- 
ward from  25  to  40  feet  per  mile,  so  that  the  depth  of  the  salt  be- 
neath the  surface  increases  in  this  direction. 

At  Ithaca,  salt  is  struck  at  2244  feet,  and  there  are  seven  beds.  The  thick- 
ness of  the  individual  beds  varies,  but  the  greatest  known  thickness  is  in  a 
well  near  Tully,  where  325  feet  of  solid  salt  was  bored  through.  Salt  has 
also  been  struck  by  a  deep  boring  in  the  oil  field  of  southwestern  New  York 
at  a  depth  of  about  3000  feet.  Though  most  of  the  New  York  product  is 
obtained  from  artificial  brines,  a  small  quantity  is  mined  by  shafts. 

Michigan  (13).  —  Salt  in  Michigan  is  obtained  both  from  natural 
brines  and  from  brines  obtained  by  dissolving  rock  salt,  as  in  New 
York.  The  natural  brines  occur  in  the  sandstones  of  the  Mississip- 
pian,  the  most  important  locality  being  in  the  Saginaw  Valley,  where 
the  brines  are  found  in  the  Napoleon  or  Upper  Marshall  sandstone. 
They  are  remarkable  for  the  large  amount  of  bromine  contained, 
more  than  half  the  bromine  produced  in  the  United  States  being 
obtained  here.  The  vast  beds  of  rock  salt  which  occur  in  the  Salina 
(Monroe)  are  exploited  along  the  Detroit  and  St.  Clair  rivers  and  at 
Manistee  and  Ludington.  The  salt  is  dissolved  by  lake  water 
pumped  down  and  then  re-evaporated,  and  soda  ash  (sodium  car- 
bonate) is  made  from  the  salt  to  a  very  great  extent,  by  forced 
reaction  with  calcium  carbonate.1 

Ohio  (16).  —  Natural  brines  are  obtained  from  the  "Big  Salt 
Sand  "  (Mississippian)  at  Pomeroy,  Meigs  County,  but  the  profit 
in  pumping  them  lies  in  the  bromine  and  calcium  chloride  which 
they  contain.  In  northeastern  Ohio  the  wells  pierce  a  bed  of  rock 
salt  in  the  Salina  (Silurian),  which  is  148  feet  thick  and  interbedded 
with  limestones  and  shales.  The  wells  are  about  1900  feet  deep  at 
Cleveland  and  2800  feet  at  Kenmore,  Summit  County. 

1  Private  communications  from  Dr.  A.  C.  Lane. 


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222 


ECONOMIC   GEOLOGY 


The  two  following  analyses  are  of  interest,  partly  on  account 
of  their  completeness.  The  absence  of  sulphate  in  the  first  is 
noticeable. 

ANALYSES  OF  OHIO  BRINES 


GRAMS  PI 

:R  LITER 

I 

II 

SiO-2                                         

.012 

.000 

Fe^Os   AhOs                  ....'.     .     . 

.083 

.000 

CaCl2     

14.340 

1.033 

MgClo    

5.59 

.462 

NaCl                                                   .... 

84.3 

310.977 

KC1  

.114 

.713 

MgBr2   

.155 

.012 

Bad"                                                  .... 

.343 

.000 

Nal  

.004 

.000 

SrClo      

.000 

.089 

CaSO4                                                      ... 

.000 

4.857 

LiOg       .     . 

tr. 

tr. 

SD   err. 

1.075 

1.204 

I.  Natural  brine,  Pomeroy,  O.     II.  Artificial  brine,  Cleveland,  O. 

Virginia  (23).  —  Salt,  associated  with  gypsum,  is  obtained  by  wells 
from  the  Mississippian  shaly  limestones  in  the  Holston  Valley  near 
Plasterco,  Washington  County  (Fig.  73).  The  product  is  used  entirely 

in   the   manufacture 

of  alkali   (22)>     The 
geology    is    referred 

to     under     Gypsum 
(p.  252). 

West  Virginia 
(24) .  —  Brine  is  ob- 
FIG.  73.  —  Section    across  Holston   and   Saltville  valleys,    tained  from  the  Car- 
midway  between  Saltville  and  Plasterco,   Va.     (After    boniferous    '     (Potts- 
Eckel,  U.  S.  Geol.  Surv.,  Bull  223.)  ville)  and  Mississip- 

pian (Berea)  in  that 

portion  of  the  state  adjoining  the  Meigs  County  salt  district  of  Ohio. 
Pennsylvania  supplies  similar  brines. 


Kansas  (9).  —  Salt  is  found  in  this  state  under  the  following  con- 
ditions: (1)  in  the  northern  and  central  parts  of  Kansas  as  brine 
in  salt  marshes  derived  by  leaching  from  the  saliferous  Dakota 
shales ;  (2)  a  limited  amount  in  eastern  Kansas  from  wells  sunk  in 


SALINES  AND  ASSOCIATED   SUBSTANCES 


223 


the  Carboniferous;  (3)  in  the  Permian  of  south  central  Kansas  as 
beds  of  rock  salt  (Fig.  74) .  At  the  present  time  the  rock  salt  is  the 
most  important  commercial  source,  being  obtained  in  part  as  arti- 
ficial brines  and  in  part  as  rock  salt.  The  thickness  of  the  salt 
varies,  the  greatest  aggregate  thickness  recorded  in  any  well  being 
324  feet.  The  deposits  thin  out  to  the  eastward,  and  the  north  and 


FIG.  74. — Geologic   section  from   Arkansas  City    to  Great   Bend,  Kas.,  showing 
occurrence  of  rock  salt.     (Kas.  Geol.  Surv.,  Min.  Res.  Bull,  1898.) 

south  limits  are  fairly  well  known,  but  the  western  boundary  re- 
mains undefined.  The  absence  of  gypsum  in  close  association  with 
the  salt  is  a  significant  fact,  but  farther  south  it  is  found  at  a  lower 
horizon,  and  the  separation  of  the  two  is  explained  by  a  shifting  sea 
bottom,  during  deposition. 

Louisiana  (10, 11, 12).  —  Brine  occurs  in  springs  and  wells  in  the 
Cretaceous  area  of  northern  Louisiana,  but  the  most  important  source 

of  salt  is  in  the  exten- 
sive beds  of  rock  salt 
found  in  the  southern 
portion  of  the  state. 
These  underlie  a  series 
of  low  knolls,  called  the 
Five  Islands  (Fig.  75), 
and  are  covered  by  a 
series  of  clay,  sand,  and 
gravel  beds.  The  salt 
occurs  as  great  dome- 
like masses  which 
Harris  thinks  have  been 
pushed  up  into  Creta- 
ceous, Tertiary,  and 
Quaternary  beds 
(p.  217).  Salt  is  mined 
on  Grande  Cote  or 


FIG.  75.  —  Map  showing  location  of  Petite  Anse  and 
other  "  salt  islands,"  Louisiana.     (After  Pomeroy.) 


224 


ECONOMIC  GEOLOGY 


Weeks  Island  and  also  on  Avery  Island.  The  age  of  the  salt  beds  is 
pre-Pleistocene.  Although  the  amount  of  rock  salt  present  is 
evidently  great,  borings  in  one  case  revealing  a  thickness  of  1756 
feet  of  solid  salt,  these  deposits  yield  but  a  small  percentage  of 
the  country's  output. 

Other  Western  States.  —  In  California  the  main  supply  of  salt  is  obtained 
by  evaporating  sea  water  (8),  an  elaborate  system  of  ponds,  covering  thou- 
sands of  acres,  having  been  built  on  San  Francisco  Bay.  These  are  filled 
at  high  tide,  and  the  brine  evaporated  by  solar  heat,  although  artificial  heat 
is  used  at  some  of  the  plants.  A  large  deposit  of  salt  was  formerly  worked 
at  Salton  Lake.  This  is  a  depression  27  miles  long,  3i  to  9  miles  wide,  and 


FIG.  76. — Section  illustrating  dome  salt  occurrence,  under  Cedar  Lick,  La.    (After 
Harris,  La.  GeoL  Surv.,  Bull.  7.) 


at  its  lowest  point  280  feet  below  sea  level.  The  deposit  is  formed  by  evapo- 
ration of  the  lake  waters,  which  are  fed  by  saline  springs  from  the  surround- 
ing foothills.  The  salt,  which  has  accumulated  to  a  depth  of  6  inches,  is 
gathered  by  scrapers.  Salt  is  also  found  in  marshes,  springs,  or  wells  in  a 
number  of  other  localities  in  California  (8). 

In  Idaho  brine  salt  is  obtained  in  Bear  Lake  and  Bannock  counties, 
near  the  Wyoming  line ;  some  also  is  produced  in  Churchill  and  Washoe 
counties,  Nevada,  Torrance  County,  New  Mexico,  and  from  saline  lakes 
in  several  parts  of  Texas.  Rock  salt  has  been  found  at  several  localities  in 
Texas,  notably  in  Mitchell  County,  and  under  the  oil  beds  at  Beaumont, 
but  none  is  yet  produced. 

In  Utah,  some  salt  is  obtained  by  evaporating  the  waters  of  Great  Salt 
Lake  (21),  and  brines  from  several  other  localities.  An  enormous  deposit 
of  pure  salt  is  reported  from  the  west  side  of  the  Utah  desert,  near  the 
Nevada  state  line.1 

Throughout  the  Red  Beds  area  of  western  Oklahama,  and  in  parts  of 
eastern  Oklahoma,  there  are  numerous  salt  springs  and  seepages,  but  Fer- 
guson is  the  only  locality  of  importance  where  salt  is  made  (18). 

1  U.  S.  Geol.  Surv.,  Min.  Res.,  1908. 


SALINES  AND  ASSOCIATED  SUBSTANCES 


225 


Canada  (27).  —  The  only  salt  deposits  now  being  exploited 
in  Canada  are  those  of  southwest  Ontario,  where  the  material  is 
obtained  from  the  Salina  formation.  There  appear  to  be  a  num- 
ber of  beds  of  varying  thickness,  interstratified  with  dolomite 
and  shale.  The  average  depth  of  the  salt  is  over  1000  feet,  and 
increases  gradually  to  the  south. 

In  the  other  Canadian  provinces  salt  springs  are  known  to 
occur  at  many  points,  but  no  deposits  of  rock  salt  have  been 
found  except  at  two  points,  viz.,  near  McMurray,  Alberta,  and 
at  Kwinitza,  B.  C. 

Other  Foreign  Deposits  (12).  —  Rock  salt  deposits  are  widely  distrib- 
uted, but  only  the  most  important  world's  producers  need  be  mentioned. 

In  England  it  is  found  in  the  Upper  Triassic  marls,  the  Cheshire  dis- 
trict having  two  important  deposits  lying  respectively  from  120  to  210  feet, 
and  240  to  300  feet,  below  the  surface.  Many  large  deposits  are  also  found 
in  the  Triassic  as  well  as  the  Permian  of  Germany.  Those  of  Stassfurt, 
are  specially  well  known.  The  German  depositsjnay  occur  as  lenses,  beds 
or  domes.  France  is  another  important  producer,  rock  salt  occurring  as 
flattened  lenses  in  saline  clays  of  the  Lorraine  Triassic,  and  in  rocks  of  the 
same  age  in  the  Pyrenees. 

In  Galicia  the  Miocene  deposits  of  Wieliczka  are  among  the  most  curious 
known.  The  upper  part  of  the  mass  consists  of  irregular  bodies  of  salt 
with  blocks  of  sandstone,  limestone  and  granite  in  saline  clays,  while  below 
it  is  stratified  salt  associated  with  clay  and  anhydrite.  Russia  contains 
abundant  supplies  in  the  southeastern  and  southern  part  of  the  country. 
Of  the  Asiatic  deposits  the  most  important,  perhaps,  are  those  lying  along 
the  Salt  Range  of  northwestern  Punjab,  where  the  beds,  underlying  gypsum, 
have  been  much  disturbed  by  tilling  and  folding. 


Analyses  of  salt. — 

ANALYSES  OF  ROCK  SALT  FROM  VARIOUS  LOCALITIES 


| 

s 

H 

H 

B  H 

H 

E  H 

89 

ido 

S^ 

jg 

LOCALITY 

%% 

E« 

11 

BS 

^  w 

s  ^~ 

M 

AUTHORITY 

sS 

^ 

<?* 

si 

^^ 

P    M    ^ 

1 

Is 

<  35 

oo 

sS 

^cg 

^^ 

•<l^ 

^ 

Retsof,  N.  Y.  .    .     . 

98701 

Tr 

446 

.743 

Tr 

F.  E.  Englehardt 

Pearl  Creek,  N.  Y.    . 

96.885 

.157 

.103 

.437 

— 

1.21 

1.21 

F.  E.  Englehardt 

Petite  Anse,  La.  .     . 

98.90 

.146 

.022 

.838 

— 

.014 

.08 

P.  Collier 

Saltville,  Va.    .     .     . 

99.084 

Tr. 

— 

.446 

— 

.47 

— 

C.  B.  Hayden 

Extraction.  —  When  salt  forms  underground  deposits,  it  has  to 
be  extracted  either  by  a  process  of  solution  or  mining.  In  the 
former  case  water  is  forced  down  to  the  salt  bed  through  a  well,  for 


226 


ECONOMIC  GEOLOGY 


ANALYSES    OF    SOLID    MATTER    OF   BRINES    FROM   VARIOUS    LOCALITIES 


H 

a 

H 

s 
5  w 

OC    Q 

sg 

h 

to 

^o 

la 

h 
O 

M    ^ 

LOCALITY 

&  * 

5  « 

33 

il 

H 

a  < 
^  W 

2  a 

S  o" 

l§s 

AUTHORITY 

il 

•<  n 
QO 

Jl 

si 

II 

Us 

Ion 

Warsaw,  N.  Y. 

97.60 

.51 

.20 

1.68 

— 

— 

26.34 

1.204 

Englehardt 

Syracuse,  N.Y. 

95.966 

.90 

.69 

2.54 

— 

.004 

18.50 

1.142 

G.  H.  Cook 

Saginaw,  Mich. 

82.14 

12.39 

5.01 

.46 

— 

— 

21.32 

— 

C.  A.  Goessman 

Bay  City,  Mich. 

91.95 

3,19 

2.48 

2.39 

— 

— 

16.61 

— 

C.  A.  Goessman 

Kanawha,  W.  Va. 

79.45 

16.48 

4.07 

— 

— 

— 

9.20 

1.073 

G.  H.  Cook 

Pittsburg,  Pa. 

81.27 

13.93 

4.80 

— 

— 

— 

2.80 

1.019 

G.  H.  Cook 

Saltville,  Va. 

97.792 

.033 

— 

2.17 

— 

Tr. 

24.60 

— 

C.  B.  Hayden 

Great  Salt  Lake 

98.10 

.322 

.000 

.364 

.021 

.214 

— 

— 

J.  E.  Talmadge 

the  purpose  of  dissolving  the  salt,  the  brine  being  brought  to  the 
surface  and  evaporated,  sometimes  by  solar  heat,  but  more  com- 
monly by  artificial  means.  In  the  latter  case  a  shaft  is  sunk  to  the 
salt  bed,  and  the  material  mined  like  coal  and  brought  to  the  sur- 
face in  lumps,  known  as  rock  salt.  Natural  brines  are  pumped  to 
the  surface  for  evaporation.  In  the  evaporation  of  brine  care  has 
to  be  taken  to  separate  the  gypsum  and  other  soluble  impurities 
present,  which  precipitate  before  the  salt  does. 

Uses.  —  Salt  is  largely  used  in  the  meat-packing  business  and 
the  manufacture  of  dairy  products,  as  well  as  for  domestic  purposes. 
Therefore  a  number  of  different  grades  are  called  for,  known  under 
various  names,  such  as  table,  dairy,  common,  fine,  packers,  solar, 
rock,  milling,  etc.  Large  quantities  of  salt  are  also  consumed  in 
the  manufacture  of  soda  ash,  sodium  carbonate,  caustic  soda,  and 
other  sodium  salts.  The  chlorination  of  gold  ores  calls  for  an  ad- 
ditional large  amount. 

Production  of  Salt.  —  The  increase  in  the  amount  of  salt  pro- 
duced has  been  very  marked,  but  it  has  been  accompanied  by  a 
decrease  in  price,  as  shown  in  the  statistics  given  below:  — 

PRODUCTION  OF  SALT  IN  UNITED  STATES,  1885  TO  1910 


YEAR 

BARRELS 

VALUE 

YEAR 

BARRELS 

VALUE 

1885       .      . 
1890       .      . 
1895       .      . 

7,038,653 
8,876,991 
13,699,649 

$4,825,345 
4,752,286 
4,423,084 

1900       .     . 
1905       .      . 
1910       .     . 

20,869,342 
25,966,122 
30,305,656  1 

$6,944,603 
6,095,922 
7,900,344 

1  Includes  production  of  Hawaii  and  Porto  Rico. 


SALINES  AND  ASSOCIATED   SUBSTANCES 


227 


PRODUCTION  OF  SALT  BY  STATES  FROM  1910  TO  1914,  IN  BARRELS 


Crp  A  rriTT. 

1910 

1911 

1912 

OTATE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

New  York     . 

111,642,520 

$2,585,739 

111,234,928 

$2,538,151 

10,527,221 

$2,615,334 

Michigan 

9,452,022 

2,231,262 

10,320,074 

2,633,155 

10,946,739 

2,974,429 

Ohio    .... 

3,673,850 

951,963 

4,302,507 

1,100,453 

5,269,179 

1,364,136 

Kansas     . 

2,811,448 

947,369 

2,159,859 

806,027 

2,573,626 

844,292 

Louisiana 

2 

2 

2 

2 

3 

3 

California 

937,514 

519,667 

1,086,163 

555,359 

1,090,000 

620,196 

West  Virginia 

155,625 

62,955 

183,379 

78,805 

139,121 

66,023 

Texas  .      .      . 

382,164 

272,568 

385,200 

299,537 

373,064 

290,328 

Utah    .      .      . 

249,850 

185,869 

272,420 

171,268 

283,293 

154,734 

Hawaii 

11,450 

9,570 

8,463 

11,850 

8,286 

9,180 

Idaho  . 

885 

1,127 

314 

532 

3 

3 

Porto  Rico    . 

3 

3 

3 

3 

3 

3 

Nevada    . 

17,535 

10,600 

12,856 

16,952 

12,536 

15,752 

Oklahoma     . 

2,564 

881 

500 

431 

3 

3 

Other  states 

4968,229 

120,774 

41,217,305 

133,172 

82,101,743 

448,368 

Total     .     .     • 

30,305,656 

$7,900,344 

31,183,968 

$8,345,692 

33,324,808 

$9,402,772 

1913 

1914 

STATE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

New  York     .      . 

10,780,514 

$2,865,187 

10,389,314 

$2,824,733 

Michigan 

11,528,800 

3,293,032 

11,670.976 

3,299,005 

Ohio     .      ... 

5,310,135 

1,313,156 

5,482,826 

1,320,554 

Kansas     . 

2,698,079 

860,404 

2,967,864 

924,550 

Louisiana      .     . 

3 

3 

3 

3 

California 

1,082,993 

759,485 

1,100,443 

856,861 

West  Virginia    . 

113,921 

63,803 

145,429 

78,036 

Texas  .... 

355.529 

278,008 

334,979 

251,493 

Utah    .... 

330,443 

191,686 

375,457 

231,512 

Hawaii 

6,071 

5,950 

Idaho  .... 

3 

3 

300 

520 

Porto  Rico    .     . 

3 

3 

3 

3 

Nevada     . 

8,971 

7,947 

4,436 

2,448 

Oklahoma     . 

3 

3 

3 

8 

Other  States      . 

82,183,842 

479,481 

62,332,649 

481,646 

Total     ,    ..  ; 

34,399,298 

$10,123,139 

34,804,683 

$10,271,358 

1  Includes  Louisiana. 

2  Included  in  New  York. 

3  Included  in  other  states. 

4  Includes  New  Mexico,  Pennsylvania,  Porto  Rico,  and  Virginia. 

5  Includes  Idaho,  Louisiana,    New    Mexico,    Oklahoma,    Pennsylvania,    Porto 
Rico,  and  Virginia. 

6  Louisiana,  New  Mexico,  Oklahoma,  Pennsylvania,  Porto  Rico,  Virginia. 

The  exports  in  1914  were  164,589,012  lb.,  valued  at  $586,055. 
The  imports  for  the  same  year  amounted  to  261,609,200  lb., 
valued  at  $380,083,  this  being  less  than  any  year  since  1902. 

Canada.  The  productior  of  salt  in  Canada  in  1913  was 
100,791  short  tons,  valued  at  $491,280,  and  in  1914,  107,038 
short  tons,  valued  at  $493,648.  The  entire  product  came  from 
Ontario. 

The  exports  from  Canada  in  1914  amounted  to  952,700  lb., 


228 


ECONOMIC  GEOLOGY 


valued  at  $5,229,  while  the  imports  for  the  year  1913  were 
144,446  tons,  valued  at  $565,283. 

PRODUCTION  OF  SALT  IN  PRINCIPAL  COUNTRIES  OF  THE  WORLD 


COUNTRY 

YEAR 

METRIC  TONS 

United  States        

1912 
1912 

4,200,000 
2,156,000 

1911 

2,087,000 

Russia 

1910 

2,047,000 

1911 

1,495,000 

1912 

1,098,000 

1911 

568,000 

1911 

342,000 

1911 

239,000 

1912 

86,200 

Italy                  

1912 

524,000 

1912 

627,000 

Greece 

1911 

60,000 

1912 

27,000 

REFERENCES    ON    SALT 

TECHNOLOGY  AND  ORIGIN.  1.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  616,  1916. 
la.  Branson,  Geol.  Soc.  Amer.,  Bull.  XXVI:  231,  1915.  2.  Englehardt, 
N.  Y.  State  Museum,  Bull.  No.  XI:  38,  1893.  2o.  Grabau,  Principles 
of  Stratigraphy,  Chapter  IX  (New  York).  26.  Hahn,  Econ.  Geol.,  VII: 
120,  1912.  (Form  of  salt  deposits.)  3.  Hubbard,  Mich.  Geol.  Surv., 
V,  Pt.  II:  1,  1895.  4.  Ochsenius,  Chem.  Zeit.,  XI,  1887.  (Bar  theory.) 
5.  Wilder,  Jour.  Geol.,  XI:  725,  1903.  6.  Harris,  Econ.  Geol.,  IV: 
12,  1909.  (Dome  theory.)  7.  Lane,  Jour.  Geol.,  XIV:  221.  (Chem- 
ical evolution  of  ocean.)  7a.  Walther,  Das  Gesetz  der  Wiistenbildung. 
(Berlin.)  (Desert  theory.) 

AREAL.  California:  8.  Bailey,  Calif.  State  Min.  Bureau,  Bull.  XXIV: 
105,  1902.  8a.  Gale,  U.  S.  Geol.  Surv.,  Bull.  580,  1914.  (Owens, 
Searles,  and  Panamint  basins.) — Kansas:  9.  Kirk  and  Haworth, 
Min.  Resources  of  Kas.,  1898:  67.  —  Louisiana:  10.  Veatch,  La. 
Exp.  Sta.,  Pt.  V:  209,  1899.  (Rock  Salt.)  11.  Veatch,  Ibid.,  Pt. 
VI:  47,  1902.  (N.  La.  salines.)  12.  Harris,  La.  Geol.  Surv.,  Bull. 
7,  1908.  (La.  and  world.)  —  Michigan:  13.  Lane,  Mich.  Geol.  Surv., 
Ann.  Rept.,  1901:  241,  1902.  13a.  Cook,  Mich.  Acad.  Sci.,  13th 
Rept.:  81,  1911.  — New  Mexico:  14.  Darton,  U.  S.  Geol.  Surv.,  Bull. 
260:  565,  1905.  (Zuni.)  —  New  York:  15.  Merrill,  N.  Y.  State 
Museum,  Bull.  11,  1893. —  Ohio:  16.  Bownocker,  O.  Geol.  Surv., 
4th  Ser.,  Bull.  8,  1906.  —  Oklahoma:  17.  Gould,  Kas,  Acad.  Soc., 
Trans.  XVII:  181,  1901.  (Salt  plains.)  18.  Snider,  Okla.  Geol. 
Surv.,  Bull.  11.  —  Texas:  19.  Cummins,  Tex.  Geol.  Surv.,  2d  Ann. 
Rept.:  444,  1890.  (Northwestern  Texas.)  20.  Richardson,  U.  S. 
Geol.  Surv.,  Bull.  260:  572,  1905.  (Trans-Pecos  regions.) —  Utah: 
21.  Phalen,  Amer.  Inst.  Min.  Engrs.,  Trans.  L:  934,  1915.  —  Vir- 
ginia: 22.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  213:  407,  1903.  (S.  W.  Va.) 
23.  Watson,  Min.  Res.  Va.,  Lynchburg,  1907.  (S.  W.  Va.)  — West 
Virginia:  24.  Grimsley,  W.  Va.  Geol.  Surv.,  IV:  286,  1909.  — Wyom- 
ing: 25.  Breger,  U.  S.  Geol.  Surv.,  Bull.  430:  555,  1910.  (Ida.-Wyo.) 


SALINES  AND  ASSOCIATED   SUBSTANCES 


229 


Canada:  26.  Bowen,  Ont.  Bur.  Mines,  XX,  pt.  I:  247,  1911,  also  XIV, 
Pt.  I:  11-8.  (Ont.)  27.  Cole,  Can.  Dept.  Mines,  Mines  Branch, 
Kept.  325,  1915.  (General.)  j 

BROMINE 

Sources.  —  Bromine  occurs  in  nature  combined  with  some 
metals,  as  in  the  minerals  Embolite,  Ag  (Cl,  Br),  Bromyrite  (Ag  Br), 
and  lodobromite  (2  Ag  Cl,  2  Ag  Br,  Ag  I),  which  theoretically  con- 
tain 25,  42.6,  and  17.8  per  cent  respectively  of  bromine.  None  of 
these  are  commercial  sources.  Sea  water  contains  about  .06  gram 
per  liter,  and  at  Stassfurt,  Germany,  the  mother  liquor  obtained 
from  salt  refining  contains  from  15  to  35  per  cent  bromine. 

In  the  United  States  bromine  is  extracted  from  natural  brines 
found  at  several  geological  horizons,  but  not  all  rock  brines  contain, 
it,  some,  as  those  of  New  York  State,  being  very  low  in  it. 

At  the  present  time  Ohio,  West  Virginia,  Pennsylvania,  and 
Michigan  brines  are  used,  the  first  bromine  having  been  manufac- 
tured in  1846  at  Freeport,  Pennsylvania. 

At  Pomeroy  and  Syracuse,  Meigs  County,  Ohio,  and  at  Hartford 
and  Mason,  Mason  County,  West  Virginia,  it  is  obtained  as  a  by- 
product of  the  salt  industry,  the  brine  coming  from  the  Pottsville 
horizon  (Big  Salt  Sand). 

A  plant  has  been  operated  also  at  Pittsburg,  Pennsylvania,  ob- 
taining the  bromine  from  brines  in  the  Pocono  sandstone.  That 
manufactured  in  Michigan  comes  from  the  Marshall  sandstone  of 
the  Lower  Carboniferous,  the  brine  containing  from  .1  to  .3  per  cent 
bromine. 

Uses.  —  Bromine  is  used  for  making  bromides  of  potash,  soda, 
and  ammonia,  for  medicinal  purposes  and  photographic  reagents. 
A  small  amount  is  employed  in  the  preparation  of  coal-tar  colors 
known  as  Eosine  and  Hoffman's  Blue.  As  a  chemical  reagent,  it 
is  utilized  for  precipitating  manganese  from  acetic  acid  solutions, 
for  the  conversion  of  arsenious  into  arsenic  acid,  etc.  It  may  also 
be  used  as  a  disinfectant  when  dissolved  in  water,  and  has  been 
employed  in  gold  extraction. 

PRODUCTION  OF  BROMINE  IN  UNITED  STATES 


YEAR 

POUNDS 

VALUE 

YEAR 

POUNDS 

VALUE 

1895 
1900       . 
1905 
1906 
1907 
1908 

517,421 
521,444 
1,192,758 
1,283,250 
1,379,496 
760,023 

$134,343 
140,790 
178,914 
165,204 
195,281 
73,783 

1909 
1910 
1911 
1912 
1913 
1914 

569,725 
245,437 
651,541 
647,200 
572,400 
576,991 

$  57,600 
31,684 
110,902 
145,805 
115,436 
203,094 

230 


ECONOMIC   GEOLOGY 


REFERENCES  ON  BROMINE 

1.  Merrill,  U.  S.  Geol.  Surv.,  Min.  Res.  1904  :  1029,  1905.    2.  Lane,  Min. 
Indus.,  XVI :  123. 


CALCIUM    CHLORIDE 

A  considerable  quantity  of  calcium  chloride  is  obtained  from 
natural  brines  in  connection  with  the  salt  and  bromine  industry 
of  Michigan,  Ohio,  and  West  Virginia.  The  figures  of  produc- 
tion since  1909  are  given  below,  but  these  do  not  include  the 
calcium  chloride  obtained  in  connection  with  the  manufacture 
of  soda,  for,  in  that  case,  it  is  not  an  original  constituent  of  the 
brine. 

The  following  are  partial  analyses  of  brines  supplying  calcium 
chloride : 


I 

II 

III 

60  172 

84  30 

141   CO 

Calcium  chloride 

15.0103 

14.34 

83.00 

Potassium  chloride 
Magnesium  chloride 

.    _- 

.5700 
4.9692 
.7447 

0.114 
5.50 
0.343 

31.00 

Strontium  chloride 
Sodium  iodide 
Sodium  bromide  . 

.2013 
.0009 
.2238 

.257 
.004 
1.155 

1  Magnesium  bromide. 

I.  Maiden,  W.  Va.,  Parts  per  1000  by  weight  (Ref.  3);  II.  Pomeroy,  O., 
Grams,  per  liter  of  brine  (Ref.  1);  III.  Napoleon  sandstone  brine, 
Saginaw  Valley,  Mich. 


QUANTITY  AND  VALUE  OF  CALCIUM  CHLORIDE  MARKETED  IN  UNITED 
STATES,  1909-1914,  IN  SHORT  TONS 


YEAR 

QUANTITY 

VALUE 

YEAH 

QUANTITY 

VALUE 

1909 
1910       .      . 
1911        .      . 

12,853 
10,971 
14,606 

$63,198 
74,713 
91,215 

1912 
1913      .      . 
1914      .      . 

18,550 
19,611 
19,403 

$117,272 
130,030 
121,766 

REFERENCES  ON  CALCIUM  CHLORIDE 

1.  Bownocker,  Ohio  Geol.  Surv  ,  Bull.  8,  1906.  2.  Cook,  Mich.  Geol. 
and  Biol.  Surv.,  Pub.  8,  Geol.  Ser.  6:  315,  1912.  3.  Grimsley,  W.  Va. 
Geol.  Surv.,  IV,  Pt.  2:  286,  1909. 


SALINES  AND   ASSOCIATED   SUBSTANCES  231 


SODIUM   SULPHATE 

Occurrence  and  Distribution. — The  hydrous  sulphate,  mirabilite 
or  Glauber  salt  (Na^SC^  +  10H2O),  is  a  white  saline  material, 
which  is  collected  on  or  near  the  surface  of  some  alkaline  marshes  in 
desert  regions.  It  may  also  be  extensively  deposited  in  some  saline 
lakes,  its  precipitation  preceding  that  of  salt,  and  being  affected 
more  or  less  by  the  season  of  the  year;  for  since  it  is  much  more 
soluble  in  warm  than  in  cold  water,  the  difference  in  temperature 
between  summer  and  winter  may  cause  its  separation  and  re-solu- 
tion (5).  The  phenomenon  has  been  noticed  in  Great  Salt  Lake 
(4).  Exposure  to  warm,  dry  air  causes  the  mirabilite  to  lose  its 
water  and  change  to  thenardite. 

No  production  of  sodium  sulphate  is  recorded  by  the  United 
States  Geological  Survey.  It  is  known  to  occur  at  several  localities 
in  Wyoming  (3),  and  some  of  the  deposits  at  least  owe  their 
origin  to  the  leaching  of  sediments.  The  deposit,  which  may  be 
as  much  as  15  feet  thick,  consists  chiefly  of  mirabilite,  epsomite, 
natrona,  and  halite  (7).  Deposits  of  some  extent  have  also 
been  noted  in  the  lowest  portion  of  the  Carriso  Plain,  along  the 
northeast  boundary  of  San  Luis  Obispo  County,  California  (6). 
In  this  lake,  which  remains  practically  dry,  except  in  very  wet 
seasons,  there  have  been  deposited  a  series  of  saline  beds,  whose 
chief  constituent  is  sodium  sulphate.  The  salt  has  been  derived 
from  the  leaching  of  soft  beds  of  conglomerate,  sandstone,  and 
shale  in  the  surrounding  hills. 

There  is  little  present  demand  for  sodium  sulphate  or  "  salt 
cake."  It  is  used  in  glass  making,  ultramarine  manufacture, 
dyeing  and  coloring,  as  well  as  to  some  extent  in  medicine  (Glau- 
ber's salt). 

REFERENCES    ON    SODIUM    SULPHATE 

1.  Attfield,  Jour.  Soc.  Chem.  Ind.,  Jan.  31,  1895.  2.  Knight,  Min.  Indus., 
Ill:  651,  1895.  3.  Knight,  Wyo.  Agric.  Exper.  Sta.,  Bull.  14,  1893. 
4.  Gilbert,  U.  S.  Geol.  Surv.,  Mon.  I:  253,  1890.  5.  Clarke,  U.  S. 
Geol.  Surv.,  Bull.  616:  233,  1916.  (General.)  6.  Arnold  and  John- 
son, U.  S.  Geol.  Surv.,  Bull.  380,  1909.  (Calif.)  7.  Schultz,  U.  S. 
Geol.  Surv.,  Bull.  430:  570,  1914.  (Wyo.)  8.  Gale,  Ibid.,  Bull.  540 .v 
428,  1914.  (Calif.) 


232  ECONOMIC  GEOLOGY 

SODIUM  CARBONATE 

Sodium  carbonate,  or  natural  soda,  is  obtained  by  the  evapora- 
tion of  the  waters  of  alkali  lakes,  or  is  found  as  a  deposit  on  or  near 
the  surface  of  alkaline  marshes  in  arid  regions.  It  is  usually  a 
mixture  of  sodium  carbonate  and  bicarbonate  in  varying  propor- 
tions, as  well  as  impurities  such  as  sodium  chloride,  sodium  sulphate, 
borax,  and  sodium  nitrate. 

Sodium  carbonate  has  been  obtained  from  Owens  Lake  in  Cali- 
fornia. An  analysis  of  the  waters  by  Chatard  yielded:  Si02,  .220; 
Fe203,  A12O3,  .038;  CaCO3,  .055;  MgCO3,  .479;  KC1,  3.137;  NaCl, 
29.415;  Na2SO4,  11.080;  Na2C03,  26.963;  NaHC03,  5.725.  The 

soda  is  purified  by  fractional  crystallization.     Soda  is  also  known 

to  occur  in  Oregon  and  Nevada. 

REFERENCES  ON  SODIUM  CARBONATE 

1.  Bailey,  Calif.  State  Min.  Bur.,  Bull.  24  :  95,  1902.  2.  Chatard,  U.  S. 
Geol.  Surv.,  Bull.  60  :  27,  1888.  (Analyses.)  3.  Russell,  U.  S.  Geol. 
Surv.,JMon.  XI:  73,  1885.  4.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  6-6: 
237,  1916. 

SODA  NITER1 


Soda  niter,  or  Chile  saltpeter  (NaNOs,  with  63.5  per  cent 
when  pure),  is  found  in  San  Bernardino  and  Inyo  counties,  Cali- 
fornia, along  the  shore  lines  marking  the  boundary  of  Death  Valley 
in  Eocene  times  (1).  It  occurs  in  peculiar  rounded  hills  of  Eocene 
clay,  the  niter  being  found  as  a  layer  near  the  surface  or  distributed 
through  the  clay.  Very  little  soda  niter  is  obtained  from  this 
source,  and  the  main  supply  of  this  country  continues  to  come  from 
Chile,  where  extensive  deposits  are  found  in  the  desert  region  west 
of  Iquique.  There  the  niter  (caliche)  forms  a  bed  6  to  12  feet  thick, 
under  a  cap  of  conglomerate  (costrd)  1  to  18  feet  thick.  The  ok'gin 
of  this  deposit  is  interesting,  and  has  caused  considerable  discus- 
sion. One  theory  quite  generally  accepted  is  that  the  niter  was 
formed  primarily  by  the  slow  oxidation  in  air  of  guano  or  other 
nitrogenous  organic  matter  in  contact  with  alkali  ;  a  second  theory 
refers  its  origin  to  the  oxidation  of  organic  materials  and  ammonia, 
by  microscopic  organisms  known  as  nitrifying  germs. 

REFERENCES  ON  SODA  NITER 

1.  Bailey,  Calif.  State  Min.  Bur.,  Bull.  24:  139,  1902.  2.  Clarke,  U.  S. 
Geol.  Surv.,  Bull.  616:  253,  1916.  (Chemistry,  analyses,  origin.) 
3.  Penrose,  Jour.  Geol.  XVIII:  1,  1910.  (Chile.)  4.  Gale,  U.  S. 
Geol.  Surv.,  Bull.  523,  1912.  (Nitrate  deposits.)  5.  Singewald  and 
Miller,  Econ.  Geol.  XI,  1916. 

1  The  term  niter,  when  used  alone,  refers  to  potash  niter. 


SALINES  AND  ASSOCIATED   SUBSTANCES  233 


BORATES 

Various  compounds  of  boron  are  known  in  nature.  When 
contained  in  complex  borosilicates  the  material  is  of  no  commer- 
cial value  as  a  source  of  borax.  It  may  also  be  present  in  vol- 
canic emanations  and  hot  spring  waters,  but  while  in  the  United 
States  these  are  of  no  importance,  in  Tuscany,  Italy,  the  gases, 
steam  and  hot  waters  are  of  value,  the  waters  being  caught  in 
basins  to  evaporate,  while  the  borax  crystallizes  out. 

In  the  United  States  the  chief  minerals  containing  boron 
are  borax,  tincal,  or  sodium  biborate,  Na2B4(>7, 10  H20;  coleman- 
ite,  Ca2B6Oii,  5  H2O;  ulexite,  CaNaB5O9,  8  H2O;  boracite,  2 
MgsBgOis,  MgCl2.  These  minerals  are  found  usually  as  incrus- 
tations in  alkaline  marshes,  in  lake  waters  of  arid  regions,  or  as 
massive  deposits. 

Distribution  in  the  United  States.  —  Deposits  of  borax  (Fig.  77) 
have  up  to  the  present  time  been  discovered  only  in  California 
(1,  2,  5),  Nevada,  and  Oregon  (3,  8).  Borax  was  originally 
obtained  by  evaporation  from  the  waters  of  Clear  Lake,1  north  of 
San  Francisco,  being  produced  in  commercial  quantities  in  1864, 
and  the  solution  was  enriched  by  crystalline  borax  obtained  from 
the  marshes  surrounding  the  lake.  This  and  other  lakes  of 
California  were  worked  until  the  discovery  of  large  deposits  of 
nearly  pure  borax  in  alkaline  marshes  of  eastern  California  and 
western  Nevada  in  the  early  seventies,  the  mineral  most  charac- 
teristic of  these  .being  ulexite.  Still  later  there  came  the  de- 
velopment north  of  Daggett,  Calif.,  of  bedded  muds  and  clays 
with  low  grade  borates  of  lime,  but  even  these  had  to  give  way  to 
the  subsequently  developed  colemanite  deposits. 

Colemanite  was  first  discovered  in  Death  Valley,  Inyo  County, 
Calif.,  in  1882,  and  in  the  following  year  12  miles  north  of  Dag- 
gett, San  Bernardino  County,  Calif.,  this  being  followed  by  its 
discovery  at  many  places  in  similar  formations  in  the  same 
general  regions  where  the  marsh  and  mud  borax  had  been  worked. 

The  colemanite,  which  has  been  referred  to  as  a  bedded  deposit, 
between  sands  and  clays,  was  supposed  by  Campbell  to  have  been 
deposited  in  a  series  of  Tertiary  lakes  (2),  but  the  beds  are  in 
many  instances  tilted,  due  to  violent  crustal  movements,  and 

1  An  analysis  of  the  solids  of  hot  spring  from  sulphur  bank  on  margin  of  Clear 
Lake  yielded  Cl,  16.49;  I,  .03;  CO2,  21.96;  B4O7,  25.61;  Na,  24.99;  NH4)  .7.88; 
A12O3,  .40;  SiO2,  2.64.  (U.  S.  Geol.  Surv.,  Bull.  330:  154.) 


234 


ECONOMIC   GEOLOGY 


LEGEND 

Colemanite  Locality 
•  Marsh  or  dry  lake  deposits 
A  Borate  waters 


FIG.  77.  —  Map  showing  borax  deposits  in  the  United  States.    (After  Yale  and  Gale> 
U.  S.  Geol.  Surv.,  Min.  Res.,  1913,) 


SALINES  AND   ASSOCIATED   SUBSTANCES 


235 


sedimentation  was  supposed  to  have  been  interrupted  at  inter- 
vals. 

A  more  recent  study  of  the  deposits  in  Ventura  County,  Calif., 
by  Gale  (3o),  gives  the  following  general  section: 

Shale  and  some  sandstone 300  feet 

Basaltic  lava  flows,  with  intercalated  lenses  of 

shale  and  limestone 600    ' 

Shale 600    " 

Conglomerate,   bowlders,   or  cobbles  of  light 

granitic  rock  cemented 600 

Other  sedimentary  rocks  below. 

The  beds,  which  are  believed  to  be  of  Miocene  age,  are  folded 
and  faulted,  and  the  most  valuable  borate  deposits  are  included 


EARLY  TERTIARY  ERUPTIVE 


FIG.  78.  —  Cross  section  of  Furnace  Canon,  Calif.,  borate  deposits.    (After  Keyes, 
Amer.  Inst.  Min.  Engrs.,  1909.) 

in  the  layers  of  shale  and  limestone  found  within  the  basalt, 
though  some  may  be  found  in  the  shales  above  and  below  the 
latter. 

The  colemanite  is  in  somewhat  irregular  masses,  lacking  a 
stratified  structure,  and  associated  with  travertine-like  limestone. 
Selenite  of  vein-like  character  is  also  present,  and  there  is  a 
practical  absence  of  any  other  salines. 

Gale  does  not  therefore  believe  the  colemanite  to  have  been 
precipitated  in  lake  basins,  but  suggests  that  emanations  of 
boric  acid  both  contemporaneous  with,  and,  possibly,  subsequent 
to  the  basalt  extrusion,  attacked  the  limestone,  replacing  carbonic 
acid  with  boric  acid,  thus  forming  the  colemanite. 

The  material  mined  showed  varying  degrees  of  purity  ranging 
from  20-25  per  cent  I^Os,  to  nearly  40  per  cent  as  shipped. 

In  this  connection  it  is  interesting  to  refer  to  an  occurrence  of 


236 


ECONOMIC   GEOLOGY 


the  boron  mineral  pandermite,  found  in  layers  and  stocks  in  beds 
of  gypsum,  in  Asia  Minor,  and  to  which  a  fumarolic  origin  has  been 
assigned.1 

The  reduction  of  colemanite  to  borax  and  boric  acid  is  accom- 
plished by  reaction  with  sodium  carbonate,  forming  the  soluble 
borax,  which  is  crystallized  in  vats. 

In  1913,  small  quantities  only  were  produced  in  Ventura  County, 
the  supply  coming  mainly  from  a  few  mines  in  Inyo  and  Los 
Angeles  counties,  California. 

Uses.  —  The  borax-bearing  minerals  are  utilized  chiefly  for  the 
manufacture  of  borax  and  boracic  acid.  Borax  is  used  in  indus- 
trial chemistry,  in  medicine,  and  as  a  laboratory  reagent.  It  is 
also  employed  in  the  assaying  of  gold  and  silver  ores,  in  soldering 
brass,  and  welding  metals. 

Boric  acid  is  used  in  the  manufacture  of  borax,  in  colored  glazes 
for  decorating  iron,  steel,  and  metallic  objects,  in  enamels  and  glazes 
for  pottery,  in  making  flint  glass,  as  an  antiseptic,  and  as  a  preser- 
vative for  food.  Chromium  borate  makes  a  green  pigment  used  in 
calico  printing,  and  manganese  borate  is  sometimes  employed  as  a 
drier  in  paints  and  oils.  Borax  is  also  extensively  used  in  numer- 
ous cosmetics. 

The  chief  refiners  are  the  Pacific  Coast  Borax  Company  with 
works  at  Bayonne,  New  Jersey,  and  Alameda,  California,  and  the 
Sterling  Borax  Company  of  San  Francisco,  California. 

Production  of  Borax.  —  The  California  colemanite  deposits  form 
the  main  source  of  domestic  supply,  the  output  being  derived  from 
the  counties  of  Los  Angeles,  Inyo,   and  Ventura.     The  marsh 
deposits  of  Nevada  are  no  longer  productive. 

The  production  of  borax  in  California  from  1909  to  1914 
was  as  follows,  the  values  being  based  on  the  boric-acid 
content  of  the  corresponding  number  of  crude  tons  of  cole- 
manite or  borate  of  lime: 


PRODUCTION  OF  BORAX  IN  CALIFORNIA 


YEAR 

SHORT  TONS 

VALUE 

YEAR 

SHORT  TONS 

VALUE 

1909       .     . 
1910       .     . 
1911       .     . 

41,434 
42,357 
53,330 

$1,534,365 
1,201,842 
1,569,151 

1912 
1913      .     . 
1914      .     . 

42,315 
58,051 
62,400 

$1,127,813 
1,491,530 
1,464,400 

1  Coulbeaux,  M.,  Ann.  Mines,  Onz.  ser,  II:   294,  1912. 


SALINES  AND  ASSOCIATED   SUBSTANCES 


237 


IMPORTS  FOR  CONSUMPTION  OF  BORAX  AND   BORATES  INTO  THE  UNITED 
STATES,  1910-1914,  IN  POUNDS 


BORATES,    CALCIUM 

BORAX 

AND  SODIUM   (CRUDE) 
AND  REFINED 

BORIC  ACID 

YEAR 

SODIUM  BORATE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

1910     . 

6860 

01170 

563 

$     66 

336,466 

$11,164 

1911     .... 

9580 

732 

28,815 

5230 

458,900 

17,666 

1912     .... 

9280 

636 

16,091 

1861 

232,545 

8,752 

1913     .... 

4215 

477 

7,900 

1025 

423,215 

16,932 

1914     .'..»-  t 

220 

29 

3,862 

546 

425,241 

18,837 

World's  Production.  Chile  and  the  United  States  are  the 
world's  leading  producers,  each  producing  in  round  numbers 
from  40,000  to  50,000  metric  tons,  mainly  calcium  borates. 
Turkey  is  probably  third,  with  a  reported  average  production  of 
14,000  tons  boracite.  Peru,  Bolivia  and  Italy  are  next  with 
2000  to  3000  tons  each. 

REFERENCES    ON    BORAX 

1.  Bailey,  Calif.  State  Mining  Bureau,  Bull.  24:  33,  1902.  (Calif,  and 
general.)  2.  Campbell,  U.  S.  Geol.  Surv.,  Bull.  200,  1902.  (Calif.) 
3.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  616:  243,  1916.  (Chemistry  of 
origin,  etc.)  3a.  Gale,  U.  S.  Geol.  Surv.,  Bull.  540:  434,  1914,  and 
Ibid.,  Prof.  Pap.  85:  3,  1914.  (Colemanite,  California.)  4.  Kemp, 
Min.  Indus.  I:  43,  1893.  (General.)  5.  Keyes,  Amer.  Inst.  Min. 
Engrs.,  Trans.,  Vol.  XL:  674,  1910.  (United  States.)  6.  Merrill, 
Non-Metallic  Minerals:  313,  N.  Y.,  1904.  7.  Spurr,  U.S.  Geol.  Surv., 
Prof.  Pap.  55:  158,  1906.  8.  Stafford,  Ore.  Univ.  Bull.,  New  Ser., 
I,  No.  4:  6,  1904.  (Oregon.)  9.  Yale  and  Gale,  U.  S.  Geol.  Surv., 
Min.  Res.  1913:  523,  1914.  (Good  bibliography.) 


IODINE 

Sources.  —  This  element  is  known  to  occur  in  sea  water,  in  min- 
eral springs,  and  in  a  few  rare  minerals,  such  as  the  iodides  of 
silver,  copper,  and  lead.  In  the  Chilean  nitrate  deposits  it  exists  as 
lautarite  [Ca(IO3)2]  and  as  a  double  salt  of  calcium  iodate  and 
chromate  [Ca(IO3)2,  CaCrOJ.  Some  Silesian  zinc  ores  and  some 
of  the  phosphate  rocks  of  France  show  small  percentages  of  the 
element.  It  has  been  found  in  the  ashes  of  sea  weeds,  and  in  some 


238  ECONOMIC   GEOLOGY 

oil-well  waters,  certain  Pennsylvania  ones  carrying  .5587  gram  of 
calcium  iodide  per  liter. 

At  present  the  entire  production  of  iodine   comes   from   two 
sources,  viz.,  the  ashes  of  sea  weeds  and  the  niter  deposits  of  Chile. 

REFERENCES  ON  IODINE 

1.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  616:  17,  119,  183,  1916.      (Many  refer- 
ences.)    2.  Min.  Indus.,  XVI :  582,  1907., 

POTASH 

The  occurrence  of  this  substance  is  referred  to  in  this  chapter, 
because  the  world's  main  source  of  supply  at  the  present  time  is 
obtained  from  deposits  of  salines.  The  element  potassium  is, 
however,  a  constituent  of  other  minerals  not  to  be  classed  as 
salines,  but  for  purposes  of  convenience  they  will  be  discussed 
here. 

Practically  all  the  potash  salts  of  mineral  origin  consumed  in 
North  American  industries  are  at  present  imported  from  abroad, 
chiefly  from  Germany.  In  1913  the  U.  S.  imports  of  potash 
salts,  not  including  kainit  and  manure  salts,  amounted  to 
612,514,916  pounds,  valued  at  $10,805,720.  The  1914  imports 
were  naturally  smaller,  due  to  the  war. 

Potash  in  Saline  Deposits.  —  A  section  of  the  remarkable 
salt  deposits  at  Stassfurt,  Prussia,  has  been  given  on  p.  213. 
While  this  locality  had  been  a  producer  of  salt  for  some  time,  the 
true  nature  and  value  of  the  potash  and  magnesia  salts  overlying 
the  rock  salt  was  not  fully  realized  until  1860.  Since  then  the 
potash  industry  has  assumed  large  proportions,  and  in  addition 
to  those  at  Stassfurt,  other  deposits  are  known  at  Hanover, 
South  Harz  mountain,  and  West  Alsatia.  Mines  are  also  operat- 
ing near  Hamburg  and  Bremen,  while  lean  deposits  with  poor 
cover  are  said  to  occur  in  Holland.1 

Small,  partly  developed  deposits  exist  near  Kaluz  in  Galicia, 
and  about  1912  lothere  were  discovered  near  Sauria,  Spain 2 
These  last  may  in  time  become  important  producers. 

The  United  States  has  not  only  been  dependent  on  Germany, 
but  has 'taken  a  large  portion  of  its  output,  and  its  dependence 
on  that  country  became  keenly  recognized  during  the  German- 
American  potash  war  of  1909-10. 

1  MacDowell,  C.  H.,  Amer.  Inst.  Min.  Engrs.,  Trans.,  LI:  424,  1916. 

2  Inst.  Geol.  de  Espana,  Bol.  34:  173,  1914. 


SALINES  AND  ASSOCIATED   SUBSTANCES 


239 


This  led  to  a  search  for  potash  in  the  United  States,  atten- 
tion being  first  turned  to  the  saline  deposits,  of  which  there  are 
several  possible  sources. 

Brines  ~and  Bitterns  (6,  7).  —  A  study  of  these  shows  that 
none  of  the  artificial  brines,  natural  brines,  or  rock-salt  deposits 
of  many  examined  contain  sufficient  potash  salts  to  render  them 
of  commercial  value  for  this  purpose.  The  following  table  gives 
the  composition  of  some. 

COMPOSITION  OF  SOLID  MATTER  IN  BRINES  FROM  SALT  WELLS 
Parts  per  Million 


1 

2 

3 

4 

5 

6 

K  .     .     . 

11.8 

3.0 

9.4 

5.8 

4.2 

2.7 

"NTn 

1ft4  4 

100  n 

7Q    7 

AQ    n 

70  o 

Ca     .     . 

4.8 

0.2 

20.2 

45.6 

36.4 

135.8 

Mg    .     . 

1.6 

tr. 

1.6 

9.8 

11.0 

48.4 

Cl      .     . 

179.1 

189.4 

135.0 

187.0 

202.2 

355.2 

SO2   .     ,  -  • 

1.6 

1.8 

2.2 

0.0 

0.8 

4.8 

Br      .     . 

1.1 

tr. 

0.4 

3.3 

11.0 

1.  Watkins,  N.  Y.,  artificial  brine;  2.  Wadsworth,  O.,  artificial  brine; 
3.  Rock  Glen,  N.  Y.,  bittern,  6  weeks'  evaporation  in  grainer,  taken  at 
time  of  run-off;  4.  Fairport  Harbor,  O.,  natural  brine;  5.  Saginaw, 
Mich.,  bittern  from  grainer.  14  days'  evaporation;  6.  Mason,  W.  Va. 
bittern,  before  going  to  bromine  still. 

Cook,  has,  however,  noted  some  brines  from  Michigan,  one  of 
which  from  the  Monroe  formation  contains  179.24  grams  per 
liter  KC1,  and  another  from  the  Dundee  limestone  containing 
158.17  grams  per  kilogram.1 

Saline  Lake  Beds  (8-13).  —  It  is  well  known  that  many  of 
the  depressions  found  in  the  Great  Basin  were  formerly  occupied 
by  lakes,  whose  waters  have  entirely  disappeared,  and  that 
during  their  existence  they  did  not  overflow.  Some  of  these  like 
the  former  Lake  Bonneville  and  Lake  Lahontan  had  considerable 
depth.  Large  quantities  of  soluble  saline  and  alkaline  substances 
were  carried  into  them  by  streams. 

In  addition  to  the  two  lakes  mentioned,  other  important  ones 
were  Mono,  Owens,  Searles  and  Panamint  of  Southern  Cali- 


1  Mich.  Acad.  Sci.,  13th  Kept.:  81,  1911. 


240 


ECONOMIC  GEOLOGY 


PROFILE  OF  THE  FORMER  OWENS  DRAINAGE  SYSTEM 


FIG.   79.  —  Map    showing  Owens   and    neighboring   lakes   of  California.     (After 
Gale,  U.  S.  Geol.  Surv.  Bull.  530,  1915.) 


SALINES  AND  ASSOCIATED   SUBSTANCES  241 

forma;  and  Lake  Le  Conte  in  the  Imperial  Valley  of  the  Colorado 
Desert,  California. 

If  now  such  a  large  body  of  water  evaporated,  the  assumption 
is  that  the  salts  would  be  left  as  a  crust  on  the  basin  floor  or  be 
absorbed  by  the  sands  and  clays  underlying  it.  Another  possi- 
bility is  that  residual  brines  may  be  found  in  the  sands  beneath 
the  basin  floor. 

Attractive  as  this  theory  apparently  is  on  first  thought,  a  care- 
ful study  of  the  subject  tends  to  the  belief  that  the  outlook 
for  finding  potash  or  other  salts  under  such  conditions  is  not  very 
promising,  so  that  most  of  the  saline  crusts,  dry-lake  areas, 
salt  flats,  sinks  or  playas  of  the  desert  region  offer  little  induce- 
ment as  a  source  of  potash.  Two  cases  may,  however,  be  men- 
tioned. 

Searles  Lake,  Calif.  (8).  In  the  evaporation  of  a  natural  saline 
solution,  containing  both  soda  and  potash,  the  latter  would  nor- 
mally remain  in  solution  much  longer,  and  hence  become  con- 
centrated in  the  residual  brine,  after  most  of  the  sodium  chloride 
had  crystallized  out,  and  theoretically  we  might  expect  to  find 
these  potash-enriched  brines  in  the  sediments  underlying  former 
lake  basins. 

The  only  important  case  of  this  sort  thus  far  discovered  is  that 
of  Searles  Lake  (Fig.  79).  This  lake,  so-called,  which  is  known 
also  as  Borax  Flat,  is  a  dry-lake  basin  of  the  ordinary  type, 
occupying  a  depression  which  could  be  filled  to  a  depth  of  640 
feet  above  the  present  salt  flat  before  it  would  overflow  into  the 
Panamint  Valley  to  the  south  and  east.  This  it  evidently  did  in 
the  past,  and,  moreover,  the  water  that  contributed  to  this  former 
high  level  was  the  overflow  from  Owens  Lake. 

At  the  present  day  we  find  the  bottom  of  this  desert  basin 
covered  by  a  great  sheet  of  solid  white  salts,  unique  in  the  variety 
of  its  saline  minerals.  This  forms  a  central  area  of  firm,  crusted 
salt,  covering  about  11  square  miles,  surrounded  by  a  zone  of 
salt-incrusted  mud  and  sand,  composed  of  salts  and  mixed  allu- 
vial material  washed  into  the  basin  from  the  surrounding  valley 
slopes. 

The  salt  of  the  central  area  is  said  to  vary  from  60-100  feet  in 
thickness,  and  it  consists  of  "  a  consolidated  mass  crystallized 
from  an  evaporating  mother-liquor  brine  in  which  the  salts  are 
still  immersed,  evaporation  being  about  balanced  by  the  influx 
of  ground  water  from  the  hill  slopes." 


242  ECONOMIC   GEOLOGY 

Analyses  of  the  brine  from  six  wells  gave  the  following  averages 
in  the  ignited  residue:  SiO2,  .02;  As,  .06;  Mg,  0;  Ca,  0;  Na, 
33.19;  K,  6.22;  CO3,  7.11;  SO4,  12.76;  Cl,  36.39;  B407,  2.45.  A 
works  for  treating  the  brine  was  being  built  in  1914,  which  was 
expected  to  handle  20,000  gallons  of  brine,  turning  out  daily: 
Borax,  225  tons;  soda  ash,  508  tons;  salt,  1507  tons;  sodium 
sulphate,  593  tons;  and  potassium  chloride,  489  tons. 

Deep  Drilling  (9-13).  Assuming  that  soluble  potash  salts 
might  be  found  in  old  lake  bottoms,  segregated  as  layers  in  such, 
or  in  mother  liquors  of  high  concentration,  attempts  have  been 
made  to  discover  these  by  drilling.  Holes  were  put  down  by  the 
United  States  Geological  Survey  near  Fallon,  Nevada,  and  in 
the  Columbus  Marsh,  near  Coaldale,  Nevada.  At  the  latter 
place  samples  taken  from  20-foot  sections,  averaged  5.96  per  cent 
water-soluble  salts  in  the  dried  material,  of  which  nearly  one-third 
is  potassium  chloride,  but  the  practical  value  of  such  saline 
muds  is  considered  problematical. 

In  bore  holes  in  Railroad  Valley,  Nye  County,  Nevada,  one  of 
the  wells  encountered  considerable  quantities  of  gaylussite 
(Na2CO3-CaC03-5H20)  but  no  potash. 

Sources  of  Potash,  not  Saline  Deposits 

Alunite.  —  This  mineral,  which  has  the  formula  K20  •  3Al2Os  • 
4SOs-6H20,  has  been  regarded  as  among  future  possibilities, 
provided  a  sufficient  quantity  exists  and  a  proper  method  of 
extraction  can  be  employed. 

Several  other  localities  have  been  recorded,  as  follows:  1.  At 
Marysvale,  Utah  (l).  2.  In  San  Cristobal  quadrangle,  Colo.  (2), 
where  there  are  several  areas  of  alunitized  granite,  consisting 
of  quartz,  pyrite  and  alunite,  the  latter  in  some  cases  forming 
29  per  cent  of  the  rock.  3.  Near  Patagonia,  Ariz.  (3);  and  4,  at 
Bovard,  Nev.  (4) .  The  last  two  are  probably  not  of  commercial 
value. 

Igneous  Rocks.  (14-17).  —  Potash  is  an  abundant  constit- 
uent of  some  igneous  rocks,  in  such  minerals  as  orthoclase  and 
leucite,  but  the  extraction  of  potash  from  these  has  not  yet 
been  worked  out  on  a  commercial  scale;  moreover,  it  is  doubtful 
whether  it  could  compete  successfully  with  that  obtained  from 
salines. 

The  possibility  of   working  feldspar  dikes  or  veins  for  this 


SALINES  AND  ASSOCIATED   SUBSTANCES  243 

purpose  has  also  been  suggested,  but  the  total  available  quantity 
from  this  source  would  not  be  large. 

It  has  also  been  suggested  that  the  vast  quantities  of  tailings 
derived  from  the  concentration  of  the  monzonite  and  other 
disseminated  copper-bearing  rocks  may  some  day  serve  as  a  source 
of  potash  (18). 

Other  Sources.  —  The  suggestion  has  been  made  that  since  potash  vola- 
tilizes in  the  burning  of  Portland  cement,  it  may  be  caught  while  passing 
up  the  stack  along  with  the  dust  which  is  precipitated  by  special  means, 
such  as  an  electrical  treater. 

The  extraction  of  potash  from  the  kelp  (18,  19)  deposits  along  the  Pacific 
coast  has  also  been  suggested. 

REFERENCES    ON    POTASH 

Alunite:  1.  Loughlhi,  U.  S.  Geol.  Surv.,  Bull.  620-K,  1915.  (Marysvale, 
Utah.)  2.  Larsen,  Ibid.,  Bull.  530:  179,  1913.  (San  Cristobal,  Colo.) 
3.  Schrader,  Ibid.,  Bull.  540:  347,1914.  (Patagonia,  Ariz.)  4.  Schrader, 
Ibid.,  Bull.  540:  351, 1914.  (Bovard,  Nev.)  5.  Waggaman,  U.  S.  Dept. 
Agric.,  Bur.  Soils,  Circ.  70,  1912.  5a.  Clapp,  Econ.  Geol.,  X:  70,  1915. 
(Brit.  Col.  Soda  alunite.)  —Brines:  6.  Phalen,  U.  S.  Geol.  Surv.,  Bull. 
530:  313,  1913.  7.  Turrentine,  U.  S.  Dept.  Agric.,  Bur.  Soils,  Bull. 
94,  1913.  (Potash  in  salines.)  7a.  Udden,  Bull.  Univ.  Tex.,  No.  17, 
1915.  (Tex.  Permian.)  —  Arid  Region  Saline  Deposits:  8.  Dolbear, 
Eng.  and  Min.  Jour.,  XCV:  259,  1913.  (Searles  Lake.)  9.  Dole, 
U.  S.  Geol.  Surv.,  Bull.  530:  330,  1913.  (Silver  Peak  Marsh,  Nev.) 
10.  Free,  U.  S.  Dept.  Agric.,  Bur.  Soils,  Circ.  61,  1912.  (Otero  Basin, 
N.  Mex.)  11.  Gale,  U.  S.  Geol.  Surv.,  Bull.  530:  295,  1913.  (Desert 
Basin  Region).  Also  Bull.  540:  339,  1914,  p.  407  (Death  Valley)  and 
p.  422  (Columbus  Marsh,  Nev.).  12.  Hicks,  U.  'S.  Geol.  Surv.,  Prof. 
Pap.  95,  1915.  (Columbus  Marsh,  Nev.)  13.  Young,  U.  S.  Dept. 
Agric.  Bull.  61.  —  Silicates:  14.  Cushman  and  Coggeshall,  8th  Internal 
Congr.  App.  Chem.,  V:  33,  1912.  15.  Herstein,  Jour.  Ind.  and  Eng. 
Chem.,  Ill,  1911.  (Feldspar.)  16.  Ross,  U.  S.  Dept.  Agric.,  Bur. 
Soils,  Circ.  71,  1912.  17.  Schultz,  U.  S.  Geol.  Surv.,  Bull.  512,  1912. 
(Leucite  Hills,  Wyo.)  18.  Butler,  U.  S.  Geol.  Surv.,  Bull.  620-J,  1915. 
(Tailings  from  copper  ores.)  — Kelp:  18.  Cameron,  Frank.  Inst.  Jour. 
CLXXVI:  347,  1913.  19.  Merz  and  Lindemuth,  Jour.  Ind.  and  Eng. 
Chem.,  V:  729,  1913. 


CHAPTER  VII 
GYPSUM 

Properties  and  Occurrence. — Gypsum  (1,4),  the  hydrous  sul- 
phate of  lime  (CaSO4,  2H20),  occurs  most  frequently  in  sedimen- 
tary rocks,  interbedded  with  shales,  sandstones,  and  limestones, 
and  often  more  or  less  closely  associated  with  rock  salt.  It  is  also 
found  as  surface  deposits  mixed  with  clay  (gypsite)  (11),  or  in  the 
form  of  sand  (5  Ariz.).  The  first  two  types  are  the  most  impor- 
tant commercially.  It  also  occurs  as  efflorescent  deposits,  periodic 
lake  deposits,  in  lumps  and  plates  scattered  through  clays  or  shales, 
in  veins,  and  in  limited  quantities  in  volcanic  regions,  especially  in 
lavas  (4).  When  occurring  in  bedded  deposits  (PL  XXV,  Fig.  2). 
it  is  often  massive,  of  crystalline  texture  or  earthy  appearance,  and 
of  variable  color,  although  most  commonly  white  and  gray. 

Transparent,  colorless  forms,  known  as  selenite,  are  found  as  veins  or 
crystals  in  the  massive  gypsum,  or  as  plates  and  crystals  in  many  clays, 
shales,  and  limestones.  This  variety  by  itself  never  forms  deposits  of  com- 
mercial importance,  although  selenite  scales  are  sometimes  plentifully 
scattered  through  the  purer  varieties.  Alabaster  is  a  pure  white,  fine- 
grained, massive  variety,  which  is  sometimes  used  for  ornamental  work. 

Gypsum  when  pure  contains  46.6  per  cent  sulphur  trioxide,  32.5 
per  cent  lime,  and  20.9  per  cent  water.  It  has  a  specific  gravity  of 
2.3,  and  a  hardness  of  1.5  to  2.  It  is  therefore  sufficiently  soft  to  be 
easily  scratched  with  a  knife  or  even  by  the  thumb  nail. 

Anhydrite  differs  from  gypsum  chemically  in  the  absence  of  water, 
but  changes  to  it  on  exposure  to  the  air  and  moisture.  In  some  cases 
it  may  have  been  derived  from  gypsum.  When  present,  it  may 
occur  as  veinlets,  beds  or  masses  in  the  gypsum  deposit;  indeed,  its 
irregularity  of  occurrence  is  at  times  puzzling  (PL  XXV,  Fig.  1). 

Anhydrite  contains  41.2  per  cent  lime,  58.8  per  cent  sulphur  tri- 
oxide. Its  specific  gravity  is  2.8  to  2.9  and  its  hardness  3  to  3.5. 
As  it  is  of  no  commercial  value,  it  may  cause  trouble  in  quarrying, 
if  present  in  large  quantities. 

Anhydrite  has  not  usually  been  regarded  as  very  abundant  in 
the  gypsum  deposits  of  the  United  States.  It  is  not  uncommon 
in  the  Virginia  mines,  and  Lane  notes  its  occurrence  in  the  deeper- 

244 


PLATE  XXV 


FIG.  1. — View  in  a  Nova  Scotia  gypsum  quarry,  showing  large  mass  of  anhydrite. 
The  anhydrite  forms  the  buttress  on  right  of  quarry  face,  and  is  not  removed. 
Good  gypsum  occurs  on  either  side  of  it.  (H.  Ries,  photo.) 


FIG.  2.  —  Gypsum  quarry,  Linden,  N  Y.     (Photo,  loaned  by  D.  H.  Newland.) 

(245) 


246  ECONOMIC   GEOLOGY 

lying  parts  of  the  Michigan  gypsum  series.  It  is  also  found  with 
gypsum  on  top  of  the  Texas  and  Louisiana  salt  deposits.  Some 
extensive  beds  also  occur  in  Oklahoma  and  a  large  mass  has  been 
found  in  Lyon  County,  Nevada.  Scattered  irregular  masses 
and  beds  are  abundant  in  some  of  the  New  Brunswick  and  Nova 
Scotia  gypsum  areas. 

Anhydrite  may  be  overlooked  because  of  its  resemblance  to  gypsum 
and  limestone,  but  although  closely  similar  to  gypsum,  the  two  can  easily 
be  distinguished  by  the  following  tests  (22)., 

Anhydrite  Gypsum 

Orthorhombic.  Monoclinic. 

Cleavage,  pseudo-cubic.  Cleavage,  perfect  in  one  direction. 

Sp.  gr.,  about  2.9.  Sp.  gr.,  about  2.3. 

Hardness,  3-3 \.  Hardness,  1|  to  2£. 

Fragments  are  square  or  rectangular,  Fragments    are    platy    with    oblique 

with  parallel  extinction.  extinction. 

Soluble  with  difficulty  in  dilute  hydro-  Easily  soluble  in  dilute  hydrochloric 

chloric  acid.  acid. 

Little  or  no  water  in  closed  tube.  Abundant  water   (20.9%)   in   closed 

tube. 

Double  refraction  rather  strong.  Double  refraction  rather  weak. 

Impurities  in  Gypsum.  —  Clay  is  probably  the  commonest 
impurity,  and  occurs  either  uniformly  distributed  through  the 
gypsum,  giving  it  an  earthy  appearance  and  gray  or  brown  color, 
or  else  it  may  be  in  layers.  Lime  carbonate  is  often  present, 
though  rarely  in  large  amounts,  although  at  times  the  gypsum 
is  interbedded  with  layers  of  limestone.  Magnesia,  silica  and 
iron  oxide  may  also  be  present,  though  not  usually  in  large 
amounts. 

Owing  to  its  solubility,  massive  gypsum  sometimes  contain 
sink  holes  and  underground  solution  channels,  that  not  only 
permit  surface  dirt  to  wash  into  the  deposit,  but  interfere  at  times 
with  the  mining. 

Origin  of  Gypsum  (4, 126,  28). —  Gypsum  is  widely  distributed 
both  geographically  and  geologically,  being  found  in  various 
horizons  from  the  Silurian  to  the  Recent.  Most  beds  of  this 
substance  have  no  doubt  been  formed  by  the  evaporation  of 
salt  water  either  in  inland  seas  or  else  in  arms  of  the  ocean,  the 
process  of  precipitation  having  been  discussed  in  the  chapter  on 
Salt.  As  gypsum  separates  from  sea  water  after  37  per  cent  of 
the  water  is  evaporated,  while  salt  precipitates  only  after  93  per 


GYSPUM  247 

cent  has  been  removed,  it  is  evident  that  gypsum  beds  may  be 
deposited  without  salt.  This  may  also  explain  why  gypsum  is 
more  widely  distributed  than  salt;  and  the  fact  that  the  percent- 
age of  gypsum  in  salt  water  is  much  less  than  that  of  salt  probably 
accounts  for  its  usual  occurrence  in  the  thinner  deposits. 

Thin  beds  of  gypsum  may  be  formed  by  water  percolating 
through  gypsum-bearing  beds,  and  subsequently  depositing  the 
gypsum  so  dissolved,  by  evaporation  on  the  surface;  or  again, 
crusts  may  accumulate  from  the  drying  up  of  the  gypsiferous 
waters  of  play  as  or  temporary  lakes. 

Gypsum  may  also  be  formed  by  the  decomposition  of  sulphides, 
such  as  pyrite,  and  the  action  of  the  sulphuric  acid  thus  liberated 
on  lime  carbonate.  Small  quantities  are  formed  in  volcanic 
regions  through  the  action  of  sulphuric  vapors  on  the  lime  of 
volcanic  tuffs  or  other  rocks  (4) . 

The  conditions  under  which  anhydrite  forms  do  not  appear  to 
be  thoroughly  understood.  According  to  Van  't  Hoff  and  Weigert, 
anhydrite  forms  from  gypsum  in  sodium  chloride  solutions  at 
30°  C.,  while  in  sea  water  the  transformation  takes  place  at  25°  C. 
(Quoted  by  Clarke,  4).  Lane  (12)  believes  that  all  calcium  sul- 
phate precipitated  at  a  greater  depth  than  500  feet  is  really  an- 
hydrite rather  than  gypsum.  Indeed,  some  believe  that  perhaps 
much  of  the  gypsum  now  found  was  originally  anhydrite. 

Vater  has  pointed  out  that  at  ordinary  temperatures  calcium 
sulphate  separates  from  a  saturated  salt  solution  as  gypsum.  The 
temperatures  noted  above  are  not  likely  to  be  found  in  sea  water, 
although  the  Persian  Gulf  (la)  has  a  mean  temperature  of  24°  C. 
owing  to  its  shallowness,  and  Grabau  suggests  that  if  in  such  a 
warmed  body  of  water  the  deeper  layers  had  become  a  con- 
centrated brine,  the  successive  influxes  of  calcium  sulphate, 
brought  in  by  waters  during  the  rainy  period  would,  on  passing 
through  these  brine  layers,  be  deposited  directly  as  anhydrite, 
in  alternating  layers  with  the  salts. 

If  the  change  of  gypsum  to  anhydrite  was  brought  about  by 
penetrating  surface  waters,  it  might  account  for  the  irregularity 
of  occurrence  of  the  anhydrite  in  the  gypsum.  That  such  a 
transformation  may  extend  to  a  considerable  depth  is  shown  by 
the  deposits  at  Bex,  Switzerland  (4),  where  the  alteration  has 
reached  a  thickness  of  60  to  100  feet. 

But  if  the  anhydrite  represents  the  original  mineral,  then  its 
change  to  gypsum  must  be  accompanied  by  increase  of  volume 


248 


ECONOMIC   GEOLOGY 


in  the  mass,  and  one  might  expect  to  find  a  shattering  or  deforma- 
tion of  the  surrounding  beds,  a  condition  actually  found  in  some 
of  the  Paleozoic  gypsum  bearing-strata.1 

Another  suggestion  is  that  originally  precipitated  gypsum  (28) 
may  change  to  anhydrite  when  buried  to  depths  of  1500  feet  or 
more.  It  is  more  than  probable  that  in  some  cases  gypsum  has 
been  the  original  mineral,  and  in  others  anhydrite,  especially  if 
either  occurs  ajone.  Where  the  two  are  irregularly  associated 
or  mixed,  the  one  may  be  derived  from  the  other,  but  where 
they  occur  in  separate  beds  with  sharp  and  even  lines  of  separa- 
tion, both  may  be  original. 


FIG.  80. —  Map  showing  gypsum-producing  localities  of  the  United  States.     (After 
Adams,  U.  S.  GeoL  Surv.,  Bull.  223.) 

Gypsite,  or  gypsum  dirt,  is  an  earthy  or  sandy  variety  of 
gypsum  forming  a  surface  deposit  in  Kansas  (ll),  and  other 
western  states  (20,  24),  which  in  spite  of  its  impure  appearance, 
may  run  high  in  calcium  sulphate.  It  is  believed  to  be  a  deposit 
either  in  the  soil  or  in  shallow  lakes  supplied  by  springs  whose 
water  has  dissolved  the  calcium  sulphate  from  gypsum  beds  or 
other  rocks.  During  its  precipitation  by  the  second  method, 
its  impure  character  is  caused  by  its  becoming  mixed  with  clay 
or  sand  washed  in  from  the  land. 


1  Grabau  and  Sherzer,  Mich.  Geol.  and  Biol.  Surv.,  Pub.  "2. 


GYSPUM 


249 


Distribution  in  the  United  States  (Fig.  "80).  —  Nineteen  states 
and  territories  are  producers  of  gypsum,  although  three  of  these — 
New  York,  Michigan,  and  Iowa — produce  nearly  50  per  cent  of 
the  total  quantity  mined. 

The  wide  geologic  range  of  gypsum  deposits  in  the  United  States 
can  be  seen  from  the  following  table :  — 


STATE  OR 
TERRITORY 

Alaska 

Arizona 

Arkansas 

California 

Colorado 

Iowa 

Kansas 

Michigan 
Montana 


AGE 

Permian  or 

Triassic 

Triassic  and  Tertiary  (Pliocene) 

Tertiary 

Tertiary 

Permian 

Permian 

Pleistocene 

Permian 

Lower  Carboniferous 

Lower  Carboniferous 


STATE  OR 
TERRITORY 

Nevada 
New  Mexico 
New  York 
Ohio 
Oklahoma 

South  Dakota 

Texas 

Utah 

Virginia 

Wyoming 


AGE 

Triassic 

Permian 

Silurian 

Silurian 

Pleistocene 

Permian 

Permian 

Permian 

Jurassic 

Carboniferous 

Triassic 


FIG.  81.  —  Map  of  New  York  showing  outcrop  of   gypsum-bearing  formations. 
(U.  S.  GeoL  Suro.,  Bull.  223.) 

New  York  (13,  14)  —  In  this  state,  which  is  one  of  the  three 
largest  producers,  the  gypsum  occurs  as  rock  gypsum,  interbedded 
with  shales  and  shaly  limestones  of  Salina  (Silurian)  age.  The  beds, 


250 


ECONOMIC  GEOLOGY 


Even  bedded  limestone 


Gyps 


Gypsur 
— SKoTi 


Light  gypsu 


Dark-gyps 
Gypsum 


Gyps 


Gypsu 


Limestone 


FIG.  82.  —  Section  in  gypsum  deposit 
at  Linden,  N.Y.  (After  Eckel, 
U.  S.  Geol.  Sure.,  Bull.  223.) 


several  of  which  may  occur  in  the 
same  section,  are  lenticular  in  shape, 
but  of  such  horizontal  extent  that 
in  any  one  quarry  they  appear  of 
uniform  thickness  (Pl.XXV,Fig.2). 
In  most  quarries  "they  range  from 
4  to  10  feet,  and  their  general  dip 
is  southward,  but  there  are  local 
irregularities.  The  main  gypsum 
deposits  occur  in  the  upper  part  of  Linden, 
the  Salina,  while  the  salt  beds  lie 
lower  down  in  this  formation.  The 
area  of  outcrop  of  the  Salina  is 
shown  in  Fig.  81.  The  gypsum  de- 
posits, which  occur  mostly  in  the 
central  part  of  the  state,  are  usually 
impure,  except  in  Genesee  County. 
Fig.  82  shows  a  not  uncommon 
mode  of  occurrence. 

Michigan    (12).  —  All  the  Mich- 
igan gypsum  is  rock  gypsum  and 

of  high  purity.  There  are  two  important  areas,  one  being 
in  the  vicinity  of  Grand  Rapids,  and  the  other  at  Alabaster 
on  Saginaw  Bay  (Plate  XXVI,  Fig.  1),  both  in  beds  of 
Lower  Carboniferous  age.  These  beds,  known  as  the  Grand 
Rapids  formation,  surround  the  Michigan  coal  basin,1  and  carry 
the  gypsum  in  their  lower  part.  At  Grand  Rapids,  the  gypsum 
beds,  which  are  interstratified  with  shale  and  limestone,  run  from 
6  to  12  feet  in  thickness,  and  are  worked  either  by  quarrying  or 
underground  chambers.  At  Alabaster,  losco  County,  the  gypsum, 
which  immediately  underlies  the  glacial  drift,  is  23  feet  thick. 

A  third,  possibly  productive,  area  is  near  St.  Ignace  on  the  upper 
peninsula,  but  there  the  gypsum  occurs  in  the  Salina  or  Monroe 
group  (Silurian). 

Iowa  (10).  —  Important  deposits  are  found  in  this  state  in  an  area 
of  about  25  square  miles  in  Webster  County,  especially  near  Fort 
Dodge.  The  gypsum,  which  is  presumably  of  Permian  age,  rests  on 
the  Coal  Measures,  or  the  St.  Louis  limestone  (Lower  Carboniferous), 

1  It  is  interesting  to  note  that  wells  sunk  in  the  central  portion  of  the  basin  show 
that  the  gypsum  passes  into  anhydrite,  indicating  that  if  the  gypsum  is  of  primary 
character  it  was  deposited  around  the  borders  of  the  old  interior  sea. 


PLATE  XXVI 


FIG.  1. — Gypsum  quarry,  Alabaster,  Mich.  Shows  gypsum  overlain  by  glacial 
drift.  The  dump  in  foreground  is  overburden  removed  from  gypsum.  (Photo., 
A.  C.  Lane.} 


FIG.  2.  —  View  in  scythestone  quarry,   Pike  Station,    N.  H.     (Photo,  loaned   by 

Pike  Mfg.  Co.) 

(251) 


252  ECONOMIC  GEOLOGY 

and  is  covered  by  glacial  drift,  but  in  places  is  overlain  conformably 
by  red  shales.  It  varies  from  3  to  30  feet  in  thickness,  with  an 
average  of  16  feet,  and  much  of  it  is  sufficiently  white  for  stucco. 
Kansas.  —  Gypsum  (11)  is  found  occurring  as  rock  gypsum,  or 
as  gypsite,  the  deposits  forming  a  belt  extending  across  the  central 
part  of  the  state  in  a  northeast-southwest  direction,  and  includes 
three  important  areas,  viz.  Northern,  or  Blue  Rapids,  in  Marshall 
County,  Central,  or  Gypsum  City,  in  Dickinson  and  Saline  counties, 
and  Southern,  or  Medicine  Lodge,  in  Barber  and  Comanche  coun- 
ties. The  beds  of  rock  gypsum  are  of  Permian  age,  interbedded 
with  red  shales,  those  at  the  southern  end  of  the  belt  being  strati- 
graphically  1000  feet  higher  than  those  at  the  northern  end. 

The  gypsite  or  gypsum  dirt,  which  is  of  more  recent  age,  is  found  in  the 
central  area,  as  well  as  at  a  number  of  other  localities.  The  spring  waters 
which  have  supplied  it  have  leached  the  calcium  sulphate  either  from 
the  gypsum  beds  or  the  red  shales.  The  gypsite  is  found  especially  in  the 
central  area,  and  the  deposits  were  the  first  of  their  kind  worked  in 
the  United  States. 

The  product  is  used  for  fertilizer  and  cement  plaster,  and  much  is  also 
used  for  making  Keene's  cement.1  The  rock,  which  is  quarried  especially 
in  the  northern  and  southern  areas,  is  white  in  color,  and  may  range  from 
8  to  16  feet  in  thickness. 

Virginia.  —  Gypsum  is  also  found  in  beds  of  Lower  Carbonif- 
erous age  in  the  Holston  Valley  of  southwestern  Virginia  (22), 
the  deposits  occurring  in  shales,  between  Carboniferous  (Green- 
brier  limestone)  and  Siluro-Devonian  sandstones  (Fig.  73).  The 
section  is  faulted  up  against  the  Cambro-Silurian  limestones,  on 
the  southeast,  and  both  the  gypsum  and  salt  deposits  seem  to  be 
limited  to  a  narrow  belt  bordering  on  this  fault. 

The  gypsum  occurs  in  bowlder  masses  in  gray  and  red  clays,  and  is 
interesting  because  of  the  abundant  but  irregular  occurrence  of  anhydrite, 
which  grades  into  the  gypsum.  The  rock  is  mined  partly  by  underground 
workings,  and  some  of  the  beds  are  fully  30  feet  thick.  The  product  is  used 
for  land  and  wall  plaster. 

In  Ohio  gypsum  has  been  obtained  from  the  lower  Helderberg  beds  of 
Ottawa  County,  10  miles  west  of  Sandusky.  The  material  occurs  at  differ- 
ent horizons,  the  beds  being  bent  into  rolls,  the  main  ones  having  a  thickness 
of  about  12  feet  (15,  20). 

Other  Occurrences.  —  Additional  occurrences  are  known  in  Wyoming 
(24,  25),  Utah  (21),  Nevada  (20),  California  (8),  Montana  (20),  Idaho  (20), 
Colorado  (9,  20),  South  Dakota  (17-19),  Oklahoma  (16),  Texas  (20),  and 
Arizona  (7,  20).  In  the  last,  as  well  as  in  New  Mexico,  there  are  found 

1  A  cement  made  by  burning  gypsum  at  high  temperatures,  and  then  treating 
ft  with  alum  or  other  chemicals. 


GYPSUM 


253 


important  deposits  of  gypsum  sand,  composed  of  gypsum  grains  broken 
down  by  stream  action  and  water  from  rock  gypsum  outcrops,  and  then 
gathered  into  hills  or  dunes  by  wind  action.  Some  of  these  dunes  are  more 
than  100  feet  high.  The  utilization  of  these  sands  in  Otero  County,  New 
Mexico,  was  begun  in  1908. 

Gypsum  (6)  of  Permian  or  Triassic  age  is  known  to  occur  on  Chichagof 
Island  in  southeastern  Alaska.  The  beds,  which  are  folded  and  steeply 
tilted,  have  been  extensively  developed  during  the  last  few  years  and  shipped 
to  Tacoma  for  preparation.  It  com.es  into  competition  with  similar  ma- 
terial from  the  western  states. 

Analyses  of  Gypsum.  —  The  following  analyses  indicate  the 
composition  of  gypsum  from  different  localities  in  the  United 
States  and  Canada.  They  cannot  all  be  guaranteed  as  being  of 
average  character,  and  serve  mainly  to  show  variation  in  com- 
position : — 


PURE 
GYPSUM 

DILLON 
KAS. 

ALA- 
BASTER 
MICH. 

GRAND 
RAPIDS 
MICH. 

SALT- 

VILLE 

VA. 

GYP- 
SITE 
MAR- 
LOW 
I.T. 

GYPSITE 
BURNS 
KAS. 

GYPSITE 
SALINA 
KAS. 

GYP- 
SITE 
DILLON 
KAS. 

CaSO*    .... 
H2O   . 

79.10 
20.90 

78.40 

19.96 
.35 
.12 
.56 
.57 

78.51 
20.96 
.05 

.08 

.11 

76.26 
20.84 
tr. 
.54 
n.d. 
n.d. 

72.06 
21.30 
1.68 
1.95 

59.46 
16.59 
10.67 
.60 
10.21 
1.10 

67.91 

17.72 
2.31 
.37 
11.71 
.52 

34.38 
8.50 
34.35 
4.11 
8.14 
10.52 

56.58 

15.16 
17.10 
2.04 
7.71 
1.24 

SiO2  

A12O3  and  Fe2O3  . 
CaCO3    .... 
MgCOs  .... 

100.00 

99.96 

99.71 

97.64 

96.99 

98.63 

100.53 

100.00 

99.83 

ONON- 

DAGA, 

N.  Y. 

FORT 
DODGE, 

lA. 

SAN- 
DUSKY 
0. 

GRAND 
ETANG 
HARBOR, 

N.  S. 

HILLS- 
BOR- 
OUGH, 

N.  B. 

MAG- 
DALEN 
IS- 
LANDS 

YORK, 
ONT. 

GYP- 

SUM- 
VILLE, 

MAN. 

SAL- 
MON 
RIVER. 
B.  C. 

CaO       .     . 
SOt  .    .    . 

173.92 

J73.44 

78.73 

32.11 
45.88 

33.00 
46.80 

32.93 
44.93 

32.70 

46.88 

30.90 
42.52 

32.60 

46.67 

H2o     .   ; 

J 

20.76 

19.70 

20.52 

20.80 

20.00 

20.66 

20.00 

20.40 

Insol.     .     . 

] 



.91 

.26 

tr. 

.60 

.06 

3.04 

.04 

Fe2O3     .     . 

4.64 





\ 

94. 

A1203     .     . 

J 

.65 

.60 

/ 

MgO     .     . 





.54 

.23 



tr. 

co2  .  ;  . 

CaO.     .     . 

>  21.44 

.80 

Distribution  of  Gyspum  in  Canada  (26,  27).  — Canada  ranks 
third  in  the  world's  production  of  gypsum,  the  United  States  and 
France  being  first  and  second  respectively,  but  over  65  per  cent 
of  the  crude  gypsum  is  exported.  The  map,  Fig.  83,  shows  a 


254 


ECONOMIC   GEOLOGY 


number  of  occurrences,  those  of  Nova  Scotia  and  New  Bruns- 
wick being  the  most  important,  followed  by  Ontario,  Manitoba 


and  British  Columbia.     In  Nova  Scotia  there  are  many  deposits, 
distributed  over  the  northern  half  of  the  province  from  Windsor 


GYPSUM  255 

to  Cape  Breton,  while  in  New  Brunswick  the  deposits  are  located 
chiefly  in  the  southern  part  of  the  province,  with  Hillsborough 
and  Plaster  Rock  as  the  two  important  localities. 

The  gypsum  of  these  two  provinces  is  of  Lower  Carboniferous 
age,  and  appears  to  form  more  or  less  lens-shaped  deposits, 
associated  with  shales  and  limestones.  Anhydrite  is  a  common 
accompanying  rock  (PI.  XXV,  Fig.  1),  and  while  in  many  cases 
it  is  said  to  underlie  the  gypsum,  it  often  occurs  in  it,  in  the  form 
of  irregular  masses  and  veinlets.  Considerable  high-grade  white 
gypsum  is  quarried  near  Hillsborough,  N.  B.  Gypsum  also  of 
Lower  Carboniferous  age  is  known  on  the  Magdalen  Islands  in 
the  Gulf  of  St.  Lawrence. 

At  York  in  southern'  Ontario,  the  Onondaga  formation  carries 
gypsum,  interstratified  with  limestone,  dolomite  and  shale. 
The  material  is  white,  and  forms  lenticular  masses  averaging 
4  feet  in  thickness,  with  some  as  much  as  11  feet  thick.  The 
northern  Ontario  deposits  are  not  worked. 

Gypsum  is  actively  worked  in  northern  Manitoba  northwest 
of  Lake  St.  Martin.  The  thinly-bedded  deposits,  which  are  some- 
times overlain  by  gypsum  earth,  may  be  10  feet  thick,  and  appear 
to  be  of  Upper  Silurian  or  Lower  Devonian  age. 

British  Columbia  contains  several  localities.  That  near 
Spat  sum  on  the  Thompson  River  is  interbedded  with  crystalline 
limestone,  argillites  and  volcanic  rocks,  while  a  second,  east  of 
Grand  Prairie,  shows  one  bed  over  100  feet  thick,  and  a  second  30 
feet  thick,  associated  with  gray  schists  and  crystalline  limestone. 

Other  Foreign  Deposits.1  —  Of  these  France  is  the  most 
important,  the  extensive  Oligocene  deposits  of  the  Paris  basin 
being  a  most  important  source  of  supply.  The  gypsum  contains 
10-20  per  cent  of  calcium  carbonate,  and  soluble  silica,  which  is 
said  to  increase  the  hardness  of  the  set  plaster.  England  is  the 
only  other  important  European  producer,  the  chief  deposits 
being  found  in  the  Triassic  of  Cumberland,  Nottinghamshire  and 
Staffordshire. 

A  number  of  other  countries  contribute  to  the  World's  supply 
(See  table  p.  258) ,  but  they  are  far  behind  the  countries  mentioned. 

Uses  (l,  12).  —  Gypsum  is  sold  either  in  the  ground,  uncal- 
cined  condition,  or  after  calcining  and  screening. 

Uncalcined  gypsum  is  used  in  large  quantities  as  a  retarder 
ior  Portland  cement,  and  in  the  past  much  was  employed  for 

1  For  resum6  see  Dammer  and  Tietze,  Nutzbaren  Mineralien,  II:  64,  1914. 


256 


ECONOMIC   GEOLOGY 


fertilizing  purposes  under  the  name  of  land  plaster.  Other  applica- 
tions are  for  crayon  manufacture,  as  an  ingredient  of  steam  pipe 
coverings,  as  a  body  for  some  paints,  and  as  a  food  adulterant 
under  the  name  of  terra  alba.  The  pure  white  rock  gypsum, 
known  as  alabaster,  has  been  used  for  statuary,  basins,  vases  and 
other  objects  for  interior  decoration. 

Calcining  Gypsum.  —  When  heated  to  250°  F.,  gypsum  loses  a  portion 
of  its  water  of  hydration,  but  if  finely  ground  has  the  property  of  recom- 
bining  with  it.  If  heated  to  300°  F.  to  400°  F.,  it  is  said  to  lose  this  power 
and  is  called  dead-burned.1  In  addition  to  dehydration,  burning  also  breaks 
up  the  crystals  into  minute  particles.  The  set  is  due  to  the  formation  of 
a  crystalline  network  of  the  rehydrated  grains. 

Since  calcined  gypsum  sets  in  from  6  to  10  minutes,  some  retarding  ma- 
terial, such  as  organic  matter  from  slaughter-house  refuse,  is  often  added 
to  it,  and  thus  the  setting  process  may  be  delayed  from  2  to  6  hours. 
Those  plasters  which  set  slowly  are  termed  cement  plasters. 

The  following  analyses  show  the  composition  of  (1)  uncalcined  gypsum; 
(2)  the  calcined  rock;  and  (3)  the  plaster  after  it  has  taken  up  water  and 
set.  From  these  it  will  be  seen  that  the  plaster  takes  up  the  amount  of 
water  lost  in  calcination. 

SERIES  OF  ANALYSES  SHOWING  CHANGES  IN  GYPSUM  DURING  BURNING 
AND  AFTER  SETTING 


CRUDE 

FINISHED 

SET 

SiO^  and  Insol  res 

1229 

1431 

12  03 

FeoOa  and  AlzOs 

227 

2  16 

1  62 

CaO   . 

2967 

33  53 

3005 

MgO  .     .     . 

.78 

91 

61 

SO3     

34.87 

3985 

35  73 

CO2 

3.52 

4.11 

3.55 

H2O    .... 

1607 

481 

1638 

In  its  calcined  form,  gypsum  comparatively  free  from  impurities 
is  known  as  plaster  of  paris,  and  has  the  following  uses  dependent 
on  its  property  of  hardening  or  setting  when  mixed  with  water: 
stucco,  plastering  for  walls,  whitewash,  pottery  molds,  statuary, 
dental  purposes,  and  as  a  bed  for  polishing  plate  glass.  Hard 
finish  plasters,  such  as  Keene's  Cement,  etc.,  and  partition  blocks 
consisting  of  plaster  of  paris  with  other  substances  are  being  used 
in  increasing  quantity. 

Production  of  Gypsum.  —  Michigan,  New  York,  and  Iowa  are 
the  leading  producers,  but  other  states  contribute  considerable 
amounts.1 

1  Recent  experiments  show  that  "  dead-burned  "  gypsum  if  ground  to  .005  mm- 
sets  readily  with  water.  W.  D.  Bancroft,  personal  communication. 


GYPSUM 


257 


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258 


ECONOMIC   GEOLOGY 


MARKETED  PRODUCTION  OF  GYPSUM  IN  THE  UNITED  STATES,   1910-1914, 

IN  SHORT  TONS 


YEAR 

SOLD  WITHOUT  CALCINING 

SOLD   AS   CALCINED   PLASTER 

TOTAL 
VALUE 

Quantity 

Value 

Average 
Price  per 
Ton 

Quantity 

Value 

Average 
Price  per 
Ton 

1910 
1911 
1912 
1913 
1914 

421,829 
387,480 
441,608 
463,136 
443,687 

$669,497 
589,479 
623,522 
697,066 
646,799 

$1.59 
1  .  52 
1.41 
1.51 
1.46 

1,583,669 
1,598,418 
1,731,674 
1,773.849 
1,656,066 

$5,853,532 
5,872,556 
5,940,386 
6,077,756 
6,249,190 

$3  .  70 
3.67 
3.43 
3.43 
3.77 

86,523,029 
6,462,035 
6,563,908 
6,774,822 
6,895,989 

The  imports  of  gypsum  for  1914  were  valued  at  $444,841. 


WORLD'S  PRODUCTION  OF  GYPSUM 


COUNTRY 

SHORT 
TONS 

VALUE 

COUNTRY 

SHORT 
TONS 

VALUE 

Algeria  (1912)  .     . 
Australia  (1912)    . 
Canada  (1913).     . 
Cyprus  (1912) 
France  (1912)  .      . 

59,965 
15,767 
636,370 
5,571 
1,979,595 

$125,064 
60,145 
1,447,739 
13,865 
3,330,311 

Germany  (1912)  . 
Greece    .... 
India  (1912)     .     . 
United  Kingdom 
(1913)        .      .     . 
United  States(1913) 

62,957 
2,475 
23,557 

319,579 
2,599,508 

$24,683 

440,174 

6,774,822 

PRODUCTION  OF  GYPSUM  IN  CANADA,  1912-1914,  IN  SHORT  TONS 


I 

912 

1 

913 

1 

914 

PROVINCE 

TONS 

VALUE 

TONS 

VALUE 

TONS 

VALUE 

Nova  Scotia  .... 
New  Brunswick  . 
Ontario      

376.082 
82,757 
53,119 
66  500 

$481,493 
185,821 
176,056 
481  250 

404,801 
103,954 
62,315 
65  100 

$479,515 
279,395 
208,029 
479  500 

303,155 
79,083 
81,219 
53,423 

$368,931 
200,680 
204,033 
382  563 

Br.  Columbia 

200 

1,300 

Total      

578,458 

$1  324  620 

636  370 

$1,447,739 

510,663 

$1,137,157 

IMPORTS  AND  EXPORTS  OF  GYPSUM  FOR  CANADA 


IMPORTS,  1913 


Crude  Gyspum 

Ground  Gypsum 

Plaster  of  Paris 

Short  Tons 

VALUE 

$21,763 

$11,770 

$154,719 

345,830 

$404,234 

EXPORTS,  1914 


GYPSUM  259 


REFERENCES    ON    GYPSUM 

PROPERTIES,  ORIGIN,  AND  TECHNOLOGY.  1.  Eckel,  Cements,  Limes,  and 
Plasters,  2d.  ed.,  N.  Y.,  1907.  la.  Grabau,  Principles  of  Stratigraphy, 
p.  373.  2.  Grimsley  and  Bailey,  Kas.  Geol.  Surv.,  V,  1899.  2a.  Rogers, 
Sch.  of  M.  Quart.,  XXXVI:  123,  1915.  (Anhydrite  in  U.  S.)  3. 
Wilder,  Eng.  and  Min.  Jour.,  LXXIV:  276,  1902.  4.  Clarke,  U.  S. 
Geol.  Surv.,  Bull.  616:  1916.  (Origin.) 

AREAL.  5.  Adams  and  others.  U.  S.  Geol.  Surv.,  Bull.  223,  1904.  (United 
States.)— Alaska:  6.  Wright,  C.  W.,  U.  S.  Geol.  Surv.,  Bull.  345: 
124,  1908.  (S.  E.  Alas.)  — Arizona:  7.  Blake,  Amer.  Geol.,  XVIII: 
394,  1896. —  California:  8.  Hess.  U.  S.  Geol.  Surv.,  Bull.  413,  1910.— 
Colorado:  9.  Lee,  Stone,  XXI:  35,  1900.  (Larimer  Co.) — Iowa: 
10.  Wilder,  la.  Geol.  Surv.,  XII:  99,  1902,  and  Jour.  Geol.,  XI:  723, 
1903.  —  Kansas:  11.  Grimsley  and  Bailey,  Kas.  Univ.  Geol.  Surv., 
V,  1899.  —  Michigan:  12.  Grimsley,  Mich.  Geol.  Surv.,  IX,  Pt.  2,  1904. 

—  Nevada:     126.  Rogers,    Econ.    Geol.    VII:     185;    1912,    and   Jones, 
Ibid.,  VII:   400,  1912.     (Origin  gypsum  and  anhydrite,  Ludwig  Mine.) 

—  New  Mexico:    12c.  Herrick,  Jour.  Geol..  VIII:    112,  1900.     (White 
sands.)  —  New  York:     13.  Merrill,    N.   Y.   State   Museum,    Bull.    11: 
70,  1893.     14.  Newland  and  Leighton,  N.  Y.  State  Mus.,  Bull.  143, 
1910.  — Ohio:    15.  Orton,  Ohio  Geol.  Surv.,  VI:    696,  1888. —Okla- 
homa:   16.  Gould  and  Herald,  Okla.  Geol.  Surv.,  Bull  5:    98,  1911. 
Also  L.  C.  Snider,  Ibid.,  Bull.  11.  — South  Dakota:    17.  U.  S.  Geol. 
Surv.,  Geol.  Atlas  Folios,  85:  6.     18.  Todd,  S.  D.  Geol.  Surv.,  Bull. 
3:   99,  1902.    19.  O'Harra,  S.  Dak.  Sch.  of  M.,  Bull.  8,   1908.— United 
States:    20.  Adams  and    others,   U.   S.   Geol.   Surv.,  Bull.  223,  1904. 

—  Utah:  21.  Boutwell,  U.  S.  Geol.  Surv.,  Bull.  225:  483,  1904.  —  Vir- 
ginia: 22.  Eckel,  U.  S.  Geol.  Surv.,    Bull.  213:  406,  1903.     23.  Watson, 
Min.  Res.  Va.:    327,    1907.     (Lynchburg.) — Wyoming:     24.    Knight, 
Wyo.  Exper.  Station,   BuU.  14:    189,  1893.     25.  Slosson  and   Moody, 
Wyo.   Coll.  Agric.   and  Mech.,   10th  Ann.  Rept.,1902. 

Canada:  26.  Cole,  Can.  Dept.  Mines,  Mines  Branch,  No.  245,  1913.  (Gen- 
eral.) 27.  Kramm,  Ibid.,  Summary  Rept.  for  1910.  (N.  S.  and  N. 
B,)  28.  Wallace,  Geol.  Mag.,  VI,  1:  271,  1914.  (Man.  and  origin.) 


CHAPTER  VIII 
FERTILIZERS 

UNDER  this  term  are  included  a  number  of  mineral  substances, 
limestone  (p.  187),  marl  (p.  191),  gypsum  (p.  244),  phosphate  of 
lime,  greensand,  guano,  kainite  (K2SO4,  MgS(>4,  MgCU,  6  H^O) 
(p.  213),  and  niter  (p.  232),  which  are  of  value  for  adding  to  the  soil 
to  increase  its  supply  of  plant  food  and  also  in  some  cases  correct 
its  physical  condition.  Some  of  these  have  other  uses  as  well,  and 
have  been  discussed  elsewhere  on  those  pages  indicated  by  the 
numbers  following  them  in  the  foregoing  lines. 

Phosphate  of  Lime.  —  This  occurs  both  as  crystalline  phosphate 
of  lime,  or  apatite,  associated  with  crystalline  rocks  and  rock  phos- 
phate usually  associated  with  stratified  rocks. 

Apatite  (6,  8) .  —  This  mineral  when  pure  contains  about  90  per 
cent  tricalcic  phosphate,  and  10  per  cent  calcium  fluoride,  which 
may  be  replaced  by  calcium  chloride.  It  is  widely  distributed  in 
some  igneous  and  metamorphic  rocks,  especially  granites,  gneisses, 
and  some  crystalline  limestones,  but  rarely  in  sufficient  quantity  or 
in  sufficiently  concentrated  masses  to  render  its  extraction  prof- 
itable, at  least  while  the  supply  of  amorphous  phosphate  lasts. 
So,  competition  with  rock  phosphate  has  restricted  mining  to  a  few 
localities  where  it  is  associated  with  other  valuable  minerals. 

In  the  United  States  apatite  has  been  produced  for  several  years 
at  Mineville,  N.  Y.  (7)  where  it  occurs  disseminated  in  small  grains 
through  the  magnetite,  forming  sometimes  as  much  as  5  per  cent  of 
the  ore.  In  the  process  of  magnetic  separation  the  apatite  is  re- 
moved as  tailings,  the  first  grade  of  these  carrying  about  60  per 
cent  tricalcium  phosphate,  and  the  second  about  30  per  cent. 
They  are  used  in  fertilizer  manufacture. 

A  unique  as  well  as  extensive  occurrence  of  phosphatic  material  is 
found  at  two  localities  in  Nelson  (figured  under  Titanium)  and  Roanoke 
counties,  Virginia.  The  rock  which  Watson  has  named  Nelsonite  (8  a) 
consists  of  a  hard  granular  aggregate  of  white  apatite  and  black  ilmenite, 
and  forms  dike-like  masses  in  metamorphic  igneous  rocks.  The  commercial 
value  of  this  material  as  a  source  of  phosphate  remains  to  be  proven. 

260 


FERTILIZERS  261 

Large  quantities  of  crystalline  apatite  were  formerly  produced 
in  Ontario  and  Quebec,  where  the  material  is  found  in  pegmatites 
associated  with  much  pyroxene,  phlogopite,  hornblende,  etc. 
The  output  at  present  is  very  limited,  as  the  material  cannot 
compete  with  the  cheaper  and  more  easily  ground  rock  phosphate. 
That  produced  is  a  by-product  from  mica  mining. 

Rock  Phosphates  (4,  4o,  8).  —  These,  though  composed  chiefly 
of  phosphate  of  lime,  also  carry  variable  quantities  of  other  sub- 
stances as  will  be  explained  below.  They  are  sometimes  called 
phosphorites,  although  this  term  should  probably  be  restricted 
to  the  purer,  denser,  fine-grained  forms.1 

Rock  phosphates  may  be  roughly  classified  as  follows: 

I.  Bedded  deposits,  consisting  of,  (a)  beds  of  massive  phosphate, 
of  continuous    or    lens-shaped    character,  and  varying  purity; 
(6)  nodules  in  sedimentary  rocks;   (c)  bone  beds  mixed  with  more 
or  less  phosphatic  material. 

II.  Replacement  deposits,  formed  by  the  leaching  of  phos- 
phate from  guano  or  higher-lying    phosphatic  formations,  and 
its  deposition  in  lower-lying  calcareous  rocks. 

III.  Cavity  fillings   deposited  from  solution,   and  including; 
(a)  irregular  cavities  in  limestones,  or  (6)  fissures  in  limestones  or 
other  rocks.     These  represent  phosphates  of  high  purity,  and 
some  replacement  may  accompany  the  filling. 

IV.  Residual  deposits. 

V.  Mechanically  formed  deposits  (placers),  of  marine  or  stream 
origin. 

Minerals  in  Phosphate  Rock.  —  The  chief  minerals  in  phos- 
phate rock  are  calcium  phosphates.  According  to  Rogers  (13) 
phosphate  rock  appears  to  be  a  mixture  of  two  minerals, 
amorphous  collophanite,  largely  a  solid  solution  of  calcium  car- 
bonate in  calcium  phosphate,  and  crystalline  dahllite,  a  calcium 
carbonophosphate  with  the  formula  Cae^O^CaCOsJEbO, 
analogous  to  fluorapatite.  The  amorphous  collophanite  gradu- 
ally changes  to  dahllite.  Hydroapatite  is  sometimes  present  in 
mammillary  masses  resembling  chalcedony. 

Phosphates  of  iron  or  aluminum  may  be  present  in  small 
amounts,  and  calcium  carbonate  is  not  rare,  though  never  present 
in  large  quantity.  Other  substances  may  include  quartz,  clay 
and  even  small  amounts  of  fluorine,  titanium,  manganese,  etc. 

1  See  Dana,  Syst.  Min.,  p.  762;  Dammer  and  Tietze,  Nutzbaren  Mineralien,  II: 
106,  1914;  Merrill,  Non-Metallic  Minerals,  p.  268;  Stutze,  Nicht-Erze,  p.  266. 


262  ECONOMIC  GEOLOGY 

Objectionable  Impurities.  —  These  may  be  objectionable  be- 
cause they  take  the  place  of  just  so  much  phosphate,  or  because 
they  interfere  with  the  process  of  manufacturing  acid  phosphate. 
Iron  and  alumina  are  the  most  objectionable  from  the  latter  view- 
point, and  hence  phosphate  is  sold  under  a  guarantee  not  to 
exceed  2  to  4  per  cent  of  iron.  Alumina  if  present  as  silicate  is 
said  to  be  more  injurious  than  aluminum  phosphate. 

A  small  amount  of  calcium  carbonate  is  beneficial,  since  its 
reaction  with  the  acid  added  generates  heat  which  promotes 
subsequent  reactions  among  the  other  constituents,  and  the  car- 
bon dioxide  gas  given  off  facilitates  drying.  Fluorine  if  present 
in  any  quantity  is  objectionable  because  of  the  obnoxious  gas 
generated,  when  the  phosphate  is  treated  with  sulphuric  acid. 
This  trouble  is  met  with  more  in  using  apatite  than  with  rock 
phosphate. 

Origin  of  Phosphate  Deposits  (2,  4,  8).  —  Considering  the 
somewhat  varied  mode  of  occurrence  of  amorphous  phosphate  it 
is  obvious  that  different  deposits  may  have  been  formed  in  different 
ways. 

We  may  perhaps  regard  the  igneous  and  other  crystalline  rocks 
as  the  ultimate  source  of  the  element  phosphorus.  The  phosphate 
minerals,  of  which  apatite  is  the  commonest,  may  on  the  weather- 
ing of  the  rock  be  attacked  by  the  soil  waters,  different  inorganic 
phosphates  showing  different  degrees  of  solubility,  and  their 
solubility  varying  also  with  the  conditions. 

Thus  the  presence  of  decaying  organic  matter  in  water  seems 
to  increase  the  solubility  of  phosphate  minerals,  and  carbonated 
water  appears  to  exert  a  similar  influence,  as  does  also  sodium 
chloride.1  Surface  waters  gather  carbon  dioxide  from  the  air, 
or  from  the  soil,  where  they  also  collect  organic  acids.  These 
then  attack  the  phosphate  compounds  found  in  the  rocks. 

While  a  part  of  this  dissolved  phosphate  of  lime  is  no  doubt 
taken  up  by  plants  or  held  in  the  soil,  other  portions  may  be 
carried  to  the  sea.  There  a  portion  of  it  may  be  abstracted  by 
marine  animals  in  the  construction  of  their  shell  covering  or 
skeletons.  The  actual  percentage  of  calcium  phosphate  in  these 
hard  parts  is  not  high,  but  it  is  not  to  be  overlooked. 

It  has  been  found  in  the  case  of  certain  swamp  waters  in  South 
Carolina,  that  calcium  phosphate  was  dissolved  when  organic 
matter  was  present  to  furnish  organic  acids.  If  these  same 
1  Patten  and  Waggaman,  Dept.  Agric.,  Bur.  Soils,  Bull.  52. 


FERTILIZERS  263 

solutions  stood  for  a  time  over  marl,  the  phosphate  was  pre- 
cipitated. Phosphate  may  also  be  precipitated  on  the  sea 
floor,  either  as  grains  or  nodules,  or  sometimes  apparently  by 
replacement  of  calcium  carbonate  of  shells  by  calcium  phos- 
phate. 

A  marine  deposit  might  therefore  contain  phosphate  formed 
by  chemical  precipitation,  as  well  as  that  contained  in  bones  and 
shells,  and  such  a  deposit  might  or  might  not  be  sufficiently  rich 
to  work. 

These  primary  deposits,  however,  may  become  the  source  of 
richer  ones  of  a  secondary  nature  by:  (1)  Leaching  out  of  calcium 
carbonate  from  phosphatic  limestones,  leaving  the  phosphate 
behind;  (2)  removal  of  the  phosphate  by  solution,  and  its 
redeposition  by  replacement  at  a  lower  horizon;  or  (3)  erosion 
of  the  phosphate  formation,  and  mechanical  concentration  of 
nodules  and  bones,  in  streams. 

We  can,  therefore,  see  that  phosphate  deposits  may  in  some 
cases  exhibit  considerable  complexity  of  origin,  involving  in  some 
cases  several  shifts  of  the  phosphatic  material. 

ROCK   PHOSPHATES   OF   THE   UNITED   STATES 

Florida  (13,  14, 15).  —  This  state  is  at  present  the  most  important 
phosphate  producer,  although  the  full  extent  and  value  of  the 
deposits  were  unsuspected  until  the  discovery  of  large  beds  along 
the  Peace  River  in  1887.  Three  distinct  types  have  been  recog- 
nized, viz.,  hard  rock,  land  pebble,  and  river  pebble,  but  the  last 
is  no  longer  important,  or  even  worked.  Their  mode  of  occur- 
rence, origin  and  location  is  different. 

The  hard  rock  phosphate  lies  in  a  general  north-south  belt, 
about  100  miles  long,  roughly  paralleling  the  Gulf  Coast,  while 
the  land-pebble  deposits  are  found  farther  south,  chiefly  in  Polk 
and  Hillsborp  counties  (Fig.  84). 

The  hard  rock  phosphate,  rests  on  and  replaces  the  porous  and 
cavernous  Ocala  limestone  (Lower  Oligocene).  It  consists  of 
boulders  and  lumps  of  phosphate  rock,  mixed  with  sands,  clays, 
flint  nodules,  etc.,  the  phosphate  often  forming  more  than  10  to 
25  per  cent  of  the  entire  mass. 

There  have  been  different  opinions  expressed  regarding  the 
origin  of  the  hard-rock  formation,  but  Sellards  (14)  especially, 
has  shown  that  the  Ocala  limestone  was  formerly  covered  by  the 


264 


ECONOMIC  GEOLOGY 


Chattahoochee  limestone  and  Alum  Bluff  sands.     These  ha  ye 
disintegrated  in  situ,  and  the  Alum  Bluff  formation,  which  is 


^-K^^ia^       ^^-~ 


I | [£. 

Longitude        83°  West          from    82°        Greenwich       81C 


su 


FIG.  84.  —  Map  showing  phosphate  areas  of  Florida.     (After  Sellards,  Fla.  Geol. 
Surv.,  '7th  Ann.  Rept.) 


distinctly  phosphatic,  has  by  leaching  supplied  the  phosphate 
which  was  carried  downward  and  redeposited  at  a  lower  level, 
often  by  replacement  of  the  limestone,  the  shells  of  which  were 
in  some  cases  completely  phosphatized.  There  was  also  some 


PLATE  XXVII 


FIG.   1.  —  Rock  phosphate  mine  near  Ocala,  Fla.      (Photo.,  A.  W.  Sheafer.) 


FIG.  2.  —  Phosphate   beds,    Montpelier,  Ido.      Shows    the    alternating    layers    of 
limestone  and  phosphate.     (W.  F,  Ferrier,  photo.) 

(265) 


266  ECONOMIC  GEOLOGY 

precipitation  of  the  phosphate  in  cavities,  as  shown  by  the 
botryoidal  and  stalactitic  forms. 

The  thickness  of  the  hard-rock  phosphate  formation  is  often 
from  30  to  50  feet,  and  in  exceptional  cases  100  feet  (14),  the 
high-grade  material  averaging  77  to  80  per  cent  tricalcic  phosphate. 

The  land  pebble  phosphate  (Fig.  84)  is  a  conglomerate  of  peb- 
bles, sands  ar>d  clay,  formed  by  the  sea  advancing,  probably  with 
minor  oscillations  in  level,  across  the  exposed  surface  of  a  great 
phosphatic  marl,  the  Alum  Bluff  formation,  while  the  overburden 
sands  represent  that  part  of  the  formation  deposited  following 
the  accumulation  of  the  pebble  conglomerate.  Within  the 
phosphate  bed,  the  rock  has  been  improved  by  secondary  enrich- 
ment by  downward- and  lateral-moving  waters,  because  the  pebbles 
of  the  phosphate  carry  considerably  more  P20s  than  those  of  the 
parent  rock. 

The  pebble  phosphate  appears  to  be  8  to  12  feet  thick,  with 
a  maximum  of  18  to  20  feet.  In  the  workable  deposits  the 
phosphate  makes  up  10  to  25  per  cent  of  the  whole,  while  the 
marketed  material  runs  from  60-74  per  cent  tricalcic  phosphate. 

Hard-rock  phosphate,  if  in  large  lumps,  is  first  crushed,  after  which,  it, 
together  with  finer  material,  passes  through  a  log  washer  to  separate  dirt 
and  sand.  Land  pebble  is  put  through  a  similar  washing  process,  some- 
times preceded  by  screening.  After  leaving  the  cleanser,  hard  rock  is  sorted 
on  a  picking  table. 

Both  kinds  of  phosphate  must  be  dried  before  shipment.  Not  a  little 
phosphoric  acid  is  to  be  regarded  as  lost  in  the  low-grade  material  which 
is  thrown  on  the  dump,  and  methods  for  saving  this  are  needed. 

South  Carolina.  —  Phosphate  is  found  both  on  the  land  and  in  the  river 
bottoms  in  a  belt  about  60  miles  long  lying  inland  from  Charleston  and 
Beaufort  (8,  20,  21).  The  phosphate,  which  rarely  averages  much  over 
1  foot  in  thickness,  is  commonly  of  nodular  character,  and  often  con- 
tains many  bones  and  teeth.  The  presence  of  these  animal  remains,  in- 
cluding both  land  and  marine  forms,  has  given  rise  to  the  belief  that  the 
deposits  were  caused  by  the  accumulation  of  bones  and  excrements  along 
a  shore  line,  probably  of  Upper  Miocene  (Tertiary)  age.  Leaching  of  these 
remains  may  have  permitted  a  later  replacement  of  limestone  or  the  forma- 
tion of  phosphatic  concretions  in  swamp  bottoms. 

Two  forms  are  recognized,  viz.,  land  rock  (the  type  now  mined)  and  river 
rock  The  foimer  ranges  from  1  to  3  feet  in  thickness  and  is  overlain  by 
green  sand  marl.  The  river  rock  is  little  more  than  water-worn  fragments 
of  the  first  type,  and  is  mined  from  the  river  channels.  The  rock  now  shipped 
averages  about  61  per  cent  bone  phosphate. 

The  South  Carolina  phosphate  rock  was  worked  as  early  as  1867,  and 
the  production  increased  up  to  1893,  but  since  then  it  has  fallen  off  almost 
steadily. 


FERTILIZERS 


267 


Tennessee  (22-28).  —  Since  the  recognition,  in  1893,  of  con- 
siderable quantities  of  high-grade  phosphates  in  western  middle 
Tennessee  (Fig.  85),  there  have  been  important  developments 
of  the  deposits. 

Three  types  of  phosphate  deposits  are  recognized,  viz.:  brown, 
blue  and  white. 

Brown  Phosphate  (26).  This  is  more  or  less  confined  to  the 
southwestern  portions  of  the  Central  Basin  of  Tennessee,  with 


FIG.  85.  —  Map  showing  distribution  of  phosphates  in  Tennessee.     (Adapted  from 
Ruhm,  Eng.  and  Min.  Jour.,  LXXXIII.) 


Mount  Pleasant  as  the  most  important  producing  district 
(Fig.  85). 

It  occurs  as  a  residum  filling  solution  cavities  or  pockets  in 
phosphatic  limestone  (Fig.  87),  which  have  been  formed  by  the 
leaching  action  of  surface  waters,  that  removed  the  lime  car- 
bonate. Where  the  parent  rock  has  not  been  exposed  to  weather- 
ing action  no  concentration  has  occurred. 

Two  types  of  deposit  are  recognized,  viz.:  (1)  Rim  or  collar 
deposits  (Plate  XXVIII,  Fig.  2)  in  which  a  more  or  less  connected 


268 


ECONOMIC  GEOLOGY 


group  encircles  a  hill,  and  (2)  Blanket  deposits  formed  where  the 
limestone  is  exposed  to  weathering  action  over  a  considerable  area. 
The  two  types  grade  into  one  another. 


UNCONFORMITY 

CHATTANOOGA  SHALE 

UNCONFORMITY  — — 


CLIFTON  LIMESTONE 


JNCONFORMITY- 

FERNVALE  FORMATION 
SHALES  AND  LIMESTONE 

UNCONFORMITY1 


0-60 


LEIPERS  FORMATION 
SHALES  AND  LIMESTONE 


CATHEYS  FORMATION 
SHALES  AND  LIMESTONE 


HERMITAGE  FORMATION 
SHALES  AND  LIMESTONE 


FIG.  86.  —  Vertical  section  showing  geologic  position  of  Tennessee  phosphates. 

(After  Hayes.) 

A  dominant  factor  is  the  presence  of  major  joints  striking 
N.  60°  W.,  and  it  is  along  these  that  the  weathering  proceeds 
(Fig.  87),  resulting  in  long  narrow  trenches,  called  cutters  (Plate 
XXVIII,  Fig.  1),  filled  with  the  commercially  valuable  phosphate. 


PLATE  XX VIII 


FIG.  1.  —  View   showing  phosphate   cutters,   Mt.   Pleasant,  Tenn.     (/.  S.  Hook, 

photo.) 


FIG.  2.  —  Collar  deposit  of  brown  Tennessee  phosphate  around  base  of  hill.    (/.  S. 

Hook,  photo.) 

(269) 


270 


ECONOMIC  GEOLOGY 


5  C=  Clay  Seam  6 

S=Soil         LS.  =  Limestone  J=J6inting  P=Phosphate 

FIG.  87.  —  Sections,  showing  development  of  "cutters"   of  brown  phosphate 
(After  Hook,  Min.  Res.  Tenn.,  IV,  No.  2,  1914.) 


FERTILIZERS  271 

These  average  about  15  feet  in  depth,  and  10  feet  in  width,  with 
maxima  of  45  feet  and  20  feet  respectively. 

The  commercial  rock  is  either  of  a  porous,  platy,  coherent 
structure,  or  of  a  loose,  sandy  nature. 

The  Bigby  limestone  (Ordovician)  from  which  the  phosphate 
is  derived,  is  when  fresh,  of  dense,  crystalline  nature,  usually 
banded  with  thin  black  layers,  which  are  more  phosphatic  than 
the  rest  of  the  rock,  and  produce  the  best  quality  of  platy  phos- 
phate. 

After  mining,  the  brown  phosphate  is  put  through  a  washer  to 
eliminate  clay,  iron  oxide,  chert,  limestone  lumps,  and  other 
foreign  matter.  The  washed  product  is  sold  under  a  guarantee 
of  from  70  to  80  per  cent  bone  phosphate,  the  maximum  specified 
amounts  of  combined  iron  and  alumina  in  each  case  being  6^ 
and  4  per  cent. 

Blue  Rock  (26).  In  Hickman,  Lewis,  Maury,  and  Perry 
counties,  especially,  there  occurs  a  phosphatic  stratum,  just 
below  the  Chattanooga  shale  in  the  Devonian,  which  varies 
from  a  few  inches  up  to  2  or  3  feet  in  thickness.  The  more 
purely  phosphatic  portion,  known  as  blue  rock,  grades  into  non- 
phosphatic  sandstone  or  shale.  Structurally  it  may  be  oolitic, 
compact,  conglomeratic  or  shaly.  Just  above  it  in  the  Chatta- 
nooga shale  is  a  layer  of  flat  phosphate  nodules. 

The  blue  rock  appears  to  be  a  sediment,  which  has  not  been 
altered  since  its  deposition,  the  phosphatic  material  having  been 
supposedly  derived  from  the  subaerial  decay  of  phosphatic 
Ordovician  limestones,  and  mechanically  concentrated  by  ocean 
currents  into  the  lenticular  deposits  from  which  it  is  now  mined. 

The  blue  rock  after  mining  is  crushed  fine. 

White  Phosphate.  —  (23,  25,  27,  28).  This  is  found  in  Perry  and 
Decatur  counties,  and  is  directly  associated  with  Silurian  lime- 
stone and  with  breccias  of  Camden  chert.  Three  varieties  of 
phosphate  are  recognized,  all  of  which  are  clearly  the  result  of 
transportation  and  deposition  by  underground  water.  They  are: 
(1)  Stony,  representing  an  originally  siliceous  limestone,  from 
which  the  calcium  carbonate  has  been  dissolved,  and  calcium 
phosphate  deposited  in  its  place.  The  phosphate,  which  forms 
27  to  33  per  cent  of  the  rock  is  therefore  a  replacement;  (2) 
Breccia,  forming  irregular  masses  of  surface  character,  and  con- 
sisting of  small  angular  fragments  of  chert,  embedded  in  a  matrix 
of  phosphate;  (3)  Lamellar ,  consisting  of  thin  parallel  layers  or 


272 


ECONOMIC   GEOLOGY 


plates,  deposited  from  solutions,  and  filling  pre-existing  solution 
channels,  or  as  a  matrix  around  chert  fragments.  This  is  the 
most  important  type. 

The  Phosphatic  material  has  probably  been  derived  from  the 
formerly  overlying  Devonian  rock,  but  since  its  deposition  is 
closely  associated  with  the  movement  of  water  through  irregular 
solution  channels,  its  distribution  must  be  regarded  as  more  or 
less  uncertain. 

ANALYSES  OF  PHOSPHATE 


FLORIDA  HARD  ROCK  PHOSPHATE 

FLORIDA  LAND 
PEBBLE 

Q 

Q  W 

. 

M 

<  o 

18 

g 

w    * 

W^ 

02  J 

°           K 

8 

3 

*  ^ 

r-l   W 

*  w 

£          (X, 

„  j 

^  ^ 

S    ^    Q 

gH 

H  ^ 

S  s  g 

g  m 

&  n 

|lz 

fc 

1^ 

JM 

" 

o  a 

Bone  phosphate       .     . 
Fe-Os     

84.40 
.32 

75.6 

.8 

67.5 
11.68 

39.42 
2.25 

75.77 
.80 

68.55 
2.24 

AhOs     

.82 

.73 

4.68 

19.17 

.60 

.84 

CaCOs  













1.32 



3.81 

SiO2  

.87 

38.40 

4.16 

TENNESSEE 

SOUTH  CAROLINA 

g 

M 

o 
o 

o 
o 

s 

rt 

rt 

lo 

Is 

g 

*~  ^ 

H  •< 

o 

« 
w 

K 
W 

O  O 

o  o 

P 

P  W 

> 

> 

«~ 

KW 

CQ 

PQ° 

a 

PH 

^ 

Bone  phosphate 

77.77 

63.5 

73.90 

26.16 

Cas(P04)2 

58.25 

54.88 

59.51 

FeoOs     
A!20s     

3.12 
2.08 

1.12 
2.00 

1.00 

J2.63 

Insol. 

11.89 

CaCOs  

0.20 

.88 

10.90 

7.79 

CaCOs 

7.98 

8.20 

8.61 

FeS2       

_       _ 

, 

1.49 

1.70 

H^O 

3   11 

1  90 

H2O 

\  

5.80 

4.31 

Org. 

J  6.58 

Western  States  (31-39).  —  Large  areas  of  phosphate  rock 
have  been  discovered  in  the  western  states  (Fig.  88),  within  the 
last  few  years.  The  deposits,  which  are  said  to  be  the  most  exten- 
sive thus  far  discovered  in  the  world,  will  no  doubt  prove  to  be  of 
great  importance  in  the  future,  although  at  present  their  develop- 
ment has  been  retarded,  partly  by  lack  of  transportation  facilities 
and  limited  demand. 


FERTILIZERS 


273 


WXASATCH 


20  30  Miles 


E~3 


Pre-Upper  Upper  Carboniferous  Post-Upper 

Carboniferous       (Phosphate  beds  near  base)       Carboniferous 

FIG.  88.  —  Map  of  parts  of  Idaho,  Wyoming,  and  Utah,  showing  localities  of  Upper 
Carboniferous  rocks  containing  phosphate  beds.     {After  Weeks  and  Ferrier,  U.  S. 
•  Geol.  Surv.,  Bull.  315,  1906.) 


274 


ECONOMIC  GEOLOGY 


IDAHO 

WYOMING 

UTAH 

Georgetown  Montpelier 

rtvl  ?  1  60  ft.4  - 

Hot  Springs 
Dingle 

—  110  ft:  

Sublette  Bits'.  Cokeville 
80ft:  L-iooffe-  — 

Crawford 
Mts. 

-200ft. 

limestone      Jo  x 

|  ||      | 


•*•  m, 


Its 

•Q.  S 


•50 


100 


-150 


-175 


200 


3  & 


I 


MS 
HI 

J  £ 


LEGEND 

LITHOLOGY 


Cherty  limestone 

Limestone 

Sandy  Unit  stone 

Shale 


Phosphate  rock 

n 

Unexposed 


PHOSPHATIC 

CONTENT 
P°        Ca(P 


34.3  QJ  75 
32. 

29.9 
27.5 


60 

23.    HHIIISO 
18.3  [Ml  40 


9.2 
4.6 


Trace 
Undetermined 


FIG.  89.  —  Columnar  sections  showing  position  and  richness  of  phosphate  beds  in 
western  states.     (17.  5.  Geol.  Surv.,  Bull.  430,  1910.) 


FERTILIZERS 


275 


They  extend  for  a  distance  of  200  miles  north  of  Ogden,  Utah, 
into  Idaho  and  Wyoming,  and  have  also  been  found  near  Ellis- 


*000- 


FIG.  90.  —  Section  showing  structure  of  phosphate  bearing  formations  in  Wyoming; 
(U.  S.  Geol  Sun.) 


Scale  in  feet 
100  200 


FIG.  91.  —  Section  of  Carboniferous  strata  on  north  side  of  Montpelier  Creek,  Ida 
(After  Weeks  and  Ferrier,  U.  S.  Geol.  Surv.,  Bull.  315,  1906.) 

ton,  Melrose,  and  other  places  in  Montana.  The  earlier  reports 
place  -them  in  the  Park  City  formation  of  the  Permian,  but  some 
of  the  later  ones  assign  the  phosphate  beds  to  the  Phosphoria 


276 


ECONOMIC  GEOLOGY 


formation,  which  is  regarded  as  the  equivalent  of  the  two  upper 
members  of  the  Park  City,  and  also  of  the  phosphatic  beds  above 
the  Quadrant  formation  of  the  Melrose  and  Elliston  district. 

The  phosphate  forms  beds  interstratified  with  limestones  and 
shales,  the  series  in  all  cases  having  been  much  disturbed  by 
folding  and  faulting.  Those  of  the  Georgetown  area  have  been 
involved  in  the  great  Bannock  thrust  fault.1 

In  hand  specimens  the  phosphate  is  seen  to  be  dense,  with  an 
oolitic  texture.  It  is  dark  brown  when  fresh,  but  becomes  bluish 
white  on  weathering.  Under  the  microscope  it  shows  an  iso- 
tropic  mineral,  possibly  collophanite,  and  a  doubly  refracting 
phosphate,  possibly  quercyite. 

The  lime  phosphate  content  of  the  workable  beds  varies  from 
65  to  80  per  cent  with  an  average  of  70  per  cent. 

Just  how  the  phosphate  has  been  formed  is  not  conclusively 
settled,  the  only  certain  fact  being  that  it  has  been  precipitated  in 
some  manner  on  the  ocean  floor. 

The  following  analyses  will  serve  to  show  its  composition: 

ANALYSES  OF  WESTERN  PHOSPHATES 


1 

2 

3 

4 

5 

CaO  .     .     .     . 

45.34 

50.97 

46.80 

48.91 

51.15 

P206  .... 

27.32 

36.35 

32.05 

33.61 

35.09 

A1203      .     .     . 

.89 

.50 

.90 

.97 

2.20 

Fe2O3.     .     .     . 

.73 

.26 

.33 

.40 

.10 

MgO      .     .     . 

.28 

.22 

.26 

.33 



XT       f\ 

11  n 

2  on 

2   no 

Q7 

K20  .    .    .     . 

,  IU 

.48 

.  uu 

.47 

.  uo 

.58 

.  »/ 
.34 



SO3    .     .     .    . 

1.59 

2.98 

2.34 

2.16 



Insol.      .     . 

10.00 

1.82 

9.40 

2.62 

4.49 

Si02  .... 

0.00 

.30 



.46 



C02   .    .    .    . 

6.00 

1.72 

2.14 

2.42 

. 

F            ... 

.60 

.40 

.66 

.40 



H2O  (110°  C.). 

1.04 

.48 

.61 

1.02 



H2O  .     .     .     . 

'1.14 

.57 

.75 

1.34 

~ 

1.  Main  bed,  Cokeville,  Wyo.;  2.  Crawford  Mts.,  Utah;  3.  Between  Morgan 
and  Devil's  Slide,  Utah;  4.  Eight  miles  E.  of  Georgetown,  Idaho; 
5.  Melrose,  Mont.;  Nos.  1-4,  U.  S.  G.  S.,  Bull.  430;  No.  5,  Bull.  470. 


1  Richards  and  Mansfield,  Jour.  Geol.  XX:  681,  1912. 


FERTILIZERS 


277 


Although  the  western  phosphate  beds  seem  to  lie  chiefly  in  the 
Permian,  still  others  are  known  to  occur  in  the  Mississippian  of 
Utah.1 

Arkansas  (10,  11,  12).  —  Phosphate  deposits  have  been  developed  on 
Lafferty  Creek,  on  the  western  edge  of  Independence  County,  but  the  beds 


FIG.  92a.  —  Oolitic  phosphate, 
Cokeville,  Wyo.     X30. 


FIG.  926.  —  Bigbee  limestone,  Mt.  Pleas- 
ant, Tenn.  Oolitic  bodies  largely 
phosphate;  light  ground  calcite 
with  phosphate  grains.  X30. 


•extend  from  about  10  miles  northeast  of  Bates ville,  to  St.  Joe  in  Searcy 
County,  a  distance  of  about  80  miles.  The  phosphate  which  forms  a 
bed  2  to  6  feet  thick  in  the  Cason  shale  of  the  Ordovician  is  light  gray, 
homogeneous  and  conglomeratic  with  small  pebbles.  It  carries  from  25 
to  73  per  cent  lime  phosphate.  The  following  section  is  shown  on  Lafferty 
Creek  (Fig.  93). 


FEET 

INCHES 

J 

Brown  to  black  shale              . 

2 

o 

I 

3 

Green  to  dark  gray  shale  »    . 

I 

2 

41-6 

Manganese-iron  ore       

2 

4 

The  Arkansas  phosphates  were  discovered  in  1895,  but  were  not  developed 
until  1900.  The  field  will  be  of  doubtful  importance  until  low  and  medium- 
..grade  rock  is  marketable. 

1  Petersen,  W.,  Science,  No.  20,  1914,  p.  755. 


278 


ECONOMIC  GEOLOGY 


•3  Inches    Clay  shale 

13    "      30.65<-o    Co- P0  0, 


'^r-^T_-  ^j— -  14    "       Phosphatic  shale 
/%§  jjS9    »       41.27$    Ca3P2Oa 


50.67$     <•     «    „ 
50.66$     ,.      ,r    n 


Phosphatic  sandstone* 


FIG.  93.  —  Section  in   Lafferty  Creek,   Ark.,  Phosphate    district. 
andNewsom,  Ark.  Agric.  Exp.  Sta.,BulL  74.) 


'After    Branner 


The  true  natuie  of  these  phosphate  deposits  does  not  appear  to  have 
been  recognized  for  some  years. 

Branner  and  Newsom  considered  them  to  be  deep-sea  (though  not  abysmal) 
deposits,  formed  from  the  droppings  of  fishes  and  other  marine  animals,  and 
to  accumulations  of  organic  matter  that  settled  to  the  bottom  of  the  quiet 
waters. 

Purdue  believed  the  beds  to  have  been  laid  down  near  shore  as  the  sea 
advanced  landward,  and  the  phosphatic  nature  as  due  mainly  to  fragments 
of  organic  matter,  but  may  have  been  in  part  the  droppings  of  marine 
animals.  .The  conglomerate  character  is  thought  by  him  to  confirm  the 
shallow-water  theory. 

Other  Phosphate  Occurrences.  —  Phosphate,  in  the  form  of  nodules, 
white  vesicular  rock,  and  in  limestone  fragments,  occurs  along  the  contact 
of  Oriskany  (Devonian)  sandstone  and  Lower  Helderberg  (Silurian) 
limestone  in  Juniata  County,  Pennsylvania  (19).  It  contains  30  to  54 
per  cent  bone  phosphate.  Nodular  phosphate,  although  not  worked  for 
fertilizer,  is  known  to  occur  in  Cretaceous  and  Tertiary  strata  in  Alabama 
(9),  Georgia  (16),  North  Carolina  (18),  and  Virginia  (29,  30).  Phosphate 
is  now  being  obtained  also  from  the  Trenton  of  central  Kentucky  (17). 

Canada.  (39o) . — The  finding  of  phosphates  at  a  definite  geologic 
horizon  in  the  western  United  States  has  encouraged  the  Cana- 
dian geologists  to  make  a  search  for  this  material  in  the  con- 
tinuation of  the  phosphate-bearing  formations  to  the  north  of 
the  international  boundary,  resulting  in  the  finding  of  phosphate 
rock  in  the  Upper  Carboniferous  a  short  distance  north  of  Banff, 
in  the  Rocky  Mountains.  The  finds  consist  of  "  float  "  phosphate 
and  also  a  phosphatic  quartzite  at  the  contact  between  the 
Upper  Banff  limestone  and  the  Rocky  Mountain  quartzite. 


FERTILIZERS 


279 


The  latter,  which  contains  7.6  per  cent.  P2Os,  is  not  rich  enough 
to  work,  but  its  discovery  warrants  further  search. 

Guano  (45,  46).  —  Under  this  name  are  included  surface  deposits  of 
excrement,  chiefly  of  birds.  Penrose  (8)  recognizes  two  classes:  (1)  soluble 
guano,  of  recent  origin,  usually  found  in  sheltered  places,  and  containing 
not  only  phosphoric  acid  in, readily  available  form,  but  also  considerable 
nitrogen.  (2)  Leached  guano,  which  has  lost  its  soluble  constituents  by 
the  action  of  rain  or  sea  water,  and  which  contains  practically  no  nitrogen, 
while  the  phosphoric  acid  content,  though  usually  high,  is  relatively  in- 
soluble. Most  of  the  soluble  guano  of  commerce  was  formerly  obtained 
from  Peru,  where,  it  is  said,  the  Incas,  as  well  as  the  early  Spaniards,  valued 
it  so  highly  that  a  death  penalty  was  imposed  for  killing  the  birds  which 
produced  it.  These  deposits,  from  which  many  thousand  tons  have  been 
obtained,  are  now  exhausted.  No  large  deposits  of  bird  guano  are  known 
in  the  United  States.  Leached  guanos  occur  on  islands  in  the  southern 
Pacific  and  in  the  West  Indies. 

Bat  guano  has  been  found  in  the  caves  of  Kentucky,  Texas  (46),  and 
many  other  states,  but  few  of  the  deposits  have  proved  large  enough  to 
work,  and  none  are  of  great  extent,  although  one  cave  in  Texas  was  known 
to  yield  1000  tons.  The  following  analysis  is  representative:  ammonia, 
9.44  per  cent;  available  phosphoric  acid,  3.17  per  cent;  potash,  1.32  per 
cent. 

Greensand.  —  This  term  is  applied  to  beds  of  marine  origin,  made  up  in 
large  part  of  the  green  sandy  grains  of  glauconite,  the  hydrated  silicate 
of  iron  and  potash.  It  also  contains  small  amounts  of  phosphoric  acid. 
Greensand  (29)  is  found  at  many  localities  in  the  Cretaceous  and  Tertiary 
formations  of  the  Atlantic  Coastal  Plain,  but  New  Jersey  (43)  and  Virginia 
are  the  two  important  producers.  The  New  Jersey  greensand  is  spread 
on  the  soil  in  its  raw  condition,  but  that  from  Virginia  is  dried  and  ground 
for  use  in  commercial  fertilizers. 

The  following  analyses  show  its  variable  composition,  and  the  com- 
paratively small  amount  of  PaOs  and  K2O  necessary  to  make  it  of  value  as 
a  fertilizer. 

ANALYSES  OF  GREENSAND 


P205 

SO3 

Si02 

CO2 

K20 

Na2O 

CaO 

MgO 

A1203 

FejO, 

H2O 

Pemberton,  N.  J. 
Aquia  Creek,  Va. 

1.02 
.09 

.27 

50.23 
21.58 

29.79 

6.32 
.37 

1.59 
.59 

1.40 
36.78 

3.45 
1.05 

7.94 
7.70 

20.14 

9.00 
.76 

Uses.  —  Fertilizers  are  used  either  in  their  raw  condition  or 
after  undergoing  preparation.  Lime  carbonate  may  be  calcined 
first,  or  ground  raw,  and  then  spread  on  the  soil.  Gypsum  is 
first  pulverized  before  being  sold  as  land  plaster. 

Phosphate    is    converted    into    acid    phosphate   by  treatment  with  sul- 
phuric acid,  and  the  manufacture  of  this  product  has  increased  enormously 


280 


ECONOMIC   GEOLOGY 


in  the  United  States.1  The  raw  materials  which  can  be  used  for  this  pur- 
pose are  guano,  bone,  apatite,  and  phosphate  rock.  Of  these  the  last  is 
the  most  important.  Only  guano  that  is  easily  obtained  and  high  in  nitrogen 
can  compete  with  phosphate  rock,  while  the  chief  objection  to  apatite  is, 
the  cost  of  mining,  and  the  evolution  of  fluorine  gas  when  treated  with 
sulphuric  acid. 

Foreign  Deposits  (4).  —  Next  to  the  United  States,  North  Africa  ranks 
as  an  important  producer,  the  deposits  of  Algiers  and  Tunis  being  of  con- 
siderable extent.  These  lie  chiefly  on  the  boundary  between  the  Cretaceous 
and  Tertiary,  and  consist  of  phosphatic  beds,  with  phosphate  nodules,  teeth, 
and  bones,  and  gypsum,  interstratified  with  phosphatic  marls  and  limestones. 
Some  of  the  deposits  are  3  meters  thick. 

In  France  there  are  a  number  of  producing  localities,  most  of  which  yield 
phosphate  from  bedded  deposits  of  Cretaceous  age,  or  in  the  Pyrenees,  beds 
of  upper  Devonian  age.  An  exception  is  formed  by  the  Quercy  phosphates, 
which  occur  as  veins  in  limestone. 

The  Belgian  deposits  are  also  bedded  and  found  in  the  Cretaceous. 

Production  of  Fertilizers.  —  The  production  of  phosphate  in 
the  United  States  for  several  years  was  as  shown  in  the  table  on 
page  281. 

Exports  and  Imports. — The  following  table  shows  what  a  large 
percentage  of  the  phosphate  rock  produced  in  the  United  States 
is  exported: 

PRODUCTION  AND  EXPORTATION  OF  PHOSPHATE  ROCK  IN  THE  UNITED  STATES, 
1909-1914,  IN  LONG  TONS 


YEAR 

PRODUCTION 

EXPORTATION 

YEAR 

PRODUCTION 

EXPORTATION 

1909. 
1910.     .     . 
1911.     .     . 

2,338,264 
2,654,988 
3,053,279 

1,020,556 
1,803,037 
1,246,577 

1912      .     . 
1913      .     . 
1914      ,     . 

2,973,332 
3,111,221 
2,734,043 

1,206,520 
1,366,508 
964,11 

These  exports  are  sent  to  all  parts  of  Europe,  Germany  being  the 
largest  consumer.     The  imports  since  1910  have  been  as  follows: — 

FERTILIZERS  IMPORTED  AND  ENTERED  FOR  CONSUMPTION  IN  THE  UNITED 
STATES,  1910-1914,  IN  LONG  TONS 


YEAR 

GUANO 

KAINIT 

ALL  OTHER 

TOTAL 

Quantity 

Value 

Quantity 

Value 

Quantity 

Value 

1910 
1911 
1912 
1913 
1914 

33,565 
36,869 
19,128 
16,674 
25,335 

$667,870 
774,315 
329,624 
518,429 
761,562 

582,197 
563,957 
511,976 
465,336 
313,898 

$2,798,198 
2,748,140 
2,386,362 
2,201,730 
1,551,115 

428,232 
428,549 
468,234 
473,426 
422,663 

$6,054,006 
7,240,017 
6,117,104 
8,099,094 
7,608,762 

$3,520,074 
10,762,472 
8,893,090 
10,819,253 
9,921,439 

1  U.  S.  Dept.  Agric.,  Bull.  144,  1914. 


FERTILIZERS 


281 


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310.505 

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Forlda: 
Hard  rock 
Land  pebble 
River  pebble 

Mil 
ra 

•g    •« 

3  i  W 

Mill 

Total 
Westert  States 

Grand  Total 

rt     ra 
J  OJ 

-.        <M 

282 


ECONOMIC  GEOLOGY 


World's  production. — The  table  given  below  is  of  interest,  since 
it  brings  out  clearly  the  leading  position  of  the  United  States  as  a 
producer  of  phosphates. 

WORLD'S   PRODUCTION   OF   PHOSPHATE   ROCK,    1910-1912,   BY  COUNTRIES, 

IN  METRIC  TONS 


1910 

1911 

1912 

COUNTRY 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

Algeria  

412,319 

$1,193,664 

738,935 

$2,139,217 

i 

i 

Australia  .... 

5,283 

25,306 

5,893 

28,226 

i 

i 

Belgium    .... 

202,880 

366,015 

196,780 

319,039 

203,110 

$316,703 

Canada     .... 

1,341 

12,578 

563 

5,206 

148 

1,640 

Christmas    Islands 

(Straits  Settlements) 

2139,903 

3 

2155,311 

3 

i 

i 

Dutch  West  Indies: 

Aruba      .... 

220,337 

106,216 

227,658 

88,430 

i 

i 

Curacao  .... 

22,165 

3,621 

21,836 

3,071 

i 

i 

France       .... 

333,506 

1,253,708 

312,204 

1,172,404 

i 

i 

French  Guiana  . 

26,925 

53,074 

i 

i 

i 

i 

French  Oceanica,  So. 

ciety  Islands     . 

240 

209 

?12,102 

46,378 

i 

i 

£lr\ni-Vi    A  fi-ir»o       XTo-f  al 

oon 

1  007 

i 

oout>n  Ainca,   isai-ai 
Tunis    

<6o\) 

1,334,264 

1  ,UU/ 

5,714,011 

1,592,000 

6,824,974 

1,882,100 

8,370,000 

United  States     .     . 

2,697,648 

10,917,000 

3,102,131 

11,900,693 

3,020,905 

11,675,774 

Statistics  not  yet  available.         2  Exports.         3  Value  not  reported. 


PRODUCTION  OF  APATITE  IN  CANADA 


YEAR 

SHORT  TONS 

VALUE 

1912     . 

164 

$1  640 

1913     

385 

3  643 

1914 

954 

7  275 

EXPORTS  AND  IMPORTS  OF  PHOSPHATE  FOR  CANADA  IN  1913 


KIND 

IMPORTS 

EXPORTS 

Phosphate  rock      
Phosphorus        
Manufactured  fertilizers      

$  16,070 
5,856 
505,904 

$73,395 

REFERENCES    ON   FERTILIZERS 

GENERAL.  1.  Adams,  Amer.  Inst.  Min.  Engrs.,  Trans.  XVIII:  649,  1890. 
(List  of  Commercial  Phosphates.)  2.  Clarke,  U.  S.  Geol.  Surv.,  Bull. 
616:  519,  1916.  (General  on  composition  and  origin.)  3.  Davidson, 
Eng.  and  Min.  Jour.,  LIII:  499,  1892.  (Deep  Sea  Formations.)  4. 
Stutzer,  Nicht-Erze,  p.  265,  1911.  4a.  Dammer  and  Tietze,  Die 
Nutzbaren  Mineralien,  II:  106,  1914.  5.  Matthew,  N.  Y.  Acad. 
Sci.,  Trans.  XII:  108,  1893.  (Nodules  of  Cambrian.)  —  Apatite: 
6.  Ells,  Can.  Rec.  Sci.,  VI:  213,  1895.  (Canada.)  7.  Newland,  N.  Y. 


FERTILIZERS  283 

State  Museum,  Bull.  102:  50,  1906.  (New  York.)  8.  Penrose,  U.  S. 
Geol.  Surv.,  Bull.  46,  1888.  (General.)  8a.  Watson,  Min.  Res.  Va.: 
300,  1907.  (Va.)  86.  de  Schmid,  Dept.  Mines,  Mines  Branch,  No.  118, 

1912.  (Canada.)      Phosphates:    Alabama:   9.  Smith,  Ala.  Geol.  Surv., 
Bull.  2:   9,  1892. — Arkansas:    10.  Branner,  Amer.  Inst.   Min.  Engrs., 
Trans.  XXVI:    580,  1897.     11.  Branner  and  Newsom,  Ark.  Exper.  Sta., 
Bull.  74,  1902.     (Many  analyses.)     12.  Purdue,  U.  S.  Geol.  Surv..  Bull. 
315:    463,    1907. — Florida:     13.  Eldridge,   Amer.   Inst.   Min.   Engrs., 
Trans.,   XXI:    196,  1893.     13a.  Matson,  U.  S.  Geol.  Surv.,  Bull.  604, 
1915.     14.  Sellards,    Fla.  Geol.  Survey,  3d  Rep.:  17,  1910;  5th  Rep.: 
23,  1913;  7th   Rep.:    25,  1915.      15.  Waggaman,    U.    S.  Dept.  Agric., 
Bur.  Soils,  Bull.  76,  1911.  —  Georgia:    16.  McCallie,  Ga.  Geol.  Surv., 
Bull.  5-A,  1896. —Kentucky:    17.  Foerste,  Ky.  Geol.  Surv.,  4th  Ser., 
I:    387,  1913.  —  North  Carolina:    18.  Carpenter,  N.  Ca.  Agric.  Exper. 
Sta.,     Bull.     110,     1894.     (Marls    and    phosphates.) — Pennsylvania: 
19.  Ihlseng,    U.  S.  Geol.  Surv.,   17th    Ann.  Rept.,  Ill:    (ctd.):    955, 
1896. —  South   Carolina:    20.  Rogers,    U.   S.   Geol.   Surv.,   Bull.   580: 
183,  1914.     21.  Waggaman,  U.  S.  Dept.  Agric.,  Bur.  Soils,  Bull.  18, 

1913.  —  Tennessee:    22.  Barr,  Amer.  Inst.  Min.  Engrs.,  Bull.  Sept., 

1914.  (Mining   and   washing.)     23.  Eckel,    U.   S.    Geol.    Surv.,    Bull. 
213:    424,    1903.     (Decatur  County.)     24.  Hayes,   U.  S.   Geol.   Surv., 
21st  Ann.  Rept.,  Ill:    473,  1901.     25.  Hayes,  Ibid.,  16th   Ann.  Rept., 
IV:    610,    1895.     (White  phosphate.)     26.  Hook,   Res.   of  Tenn.,   IV, 
No.  2,  1914.     (Brown  and  blue  phosphate.)     27.  Hook,  Ibid.,  V,  No. 
1,    1915.     (White   phosphate.)     28.  Waggaman,    U.    S.    Dept.    Agric., 
Bur.   Soils,   Bull.   81,    1912.     (General.) —Virginia:    29.  Stose,   U.   S. 
Geol.  Surv.,  Bull.  540:    383,  1914.     30.  Watson,  Min.  Res.  Va.:    302, 
1907.  —  Western  States:    31.  Weeks  and  Ferrier,  U.  S.  Geol.  Surv., 
Bull.  315:    449,  1907.     32.  Blackwelder,  Ibid.,  Bull.,  470:    452,  1911. 
(E.    Ido.)     33.  Schultz    and    Richards,    Ibid.,    Bull.    530:     267,    1913. 
(Ido.)     34.  Gale  and  Richards,  Ibid.,  Bull.  430,  1910.     35.  Blackwelder, 
Ibid.,    Bull.    430:     82,    1910.     (Utah.)     36.  Pardee,    Ibid.,    Bull.    530: 
285,   1913.     (Mont.)     37.  Richards  and  Gale,  Ibid.,  Bull.  577,   1914. 
(Ido.)     38.  Stone  and  Bonine,  Ibid.,  Bull.  580:    373,   1914.     (Mont.) 
39.  Waggaman,  U.  S.  Dept.  Agric.,  Bur.  Soils,  Bull.  69,  1910.     (General.) 
Canada:    39a.  Adams    and    Dick.  Report    for    Can.  Conserv'n  Com., 
Ottawa,    1915.     (Phosphate   in   Rocky   Mts.)     Greensand:   40.  Clark 
and  Martin,  Md.  Geol.  Surv.,  Rept.  on  Eocene,  1901.     (Maryland.) 
41.  Cook,  Geol.  of  N.  J.,  1868:    261,  1868.     42.  Parsons,  U.  S.  Surv. 
Min.    Res.,    1901:    823,    1902.     (General.)     43.  Prather,    Jour.    Geol., 
XIII:    509,   1905.     (N.  J.  glauconite.)     44.  Watson,   Min.  Res.  Va.: 
396,  1907.     Guano:  45.  Penrose,  U.  S.  Geol.  Surv.,  Bull.  46:  117,  1898. 
46.  Phillips,  Mines  and  Minerals,  XXI;  440, 1901,     (Texas  Bat  Guano.) 


CHAPTER  IX 

ABRASIVES 

Introductory.  —  Under  this  heading  are  included  those  natural 
products  which  are  employed  for  abrasive  purposes.  Since  the 
main  use  of  some  is  not  for  work  of  abrasion,  they  are  simply  re- 
ferred to  briefly  in  this  chapter,  the  detailed  description  of  them 
being  given  on  another  page.  Brief  reference  will  also  be  made 
to  some  artificial  compounds  which  come  into  serious  competition 
with  the  natural  ones. 

While  some  abrasive  substances  occur  as  constituents  of 
veins,  or  in  disseminated  form,  the  great  majority  form  a  part 
of  rocks  of  either  sedimentary,  igneous,  or  metamorphic  origin, 
and  of  various  degrees  of  consolidation.  They  are  widely  dis- 
ributed  both  geologically  and  geographically,  but  since  the  local- 
ities of  production  change  from  time  to  time,  their  distribution 
can  be  better  illustrated  by  the  table  on  page  286  than  by 
a  map. 

Millstones  and  Buhrstones  1  (2)  are  stones  of  large  diameter 
used  for  grinding  cereals,  paint  ores,  cement  rock,  barite,  fertilizers, 
etc.  The  American  stones  are  either  coarse  sandstone  or  quartz 
conglomerate,  and  are  quarried  at  several  points  along  the  eastern 
side  of  the  Appalachian  Mountains  from  New  York  to  North  Caro- 
lina, the  most  important  being  the  Shawangunk  Grit  (Silurian) 
quarried  in  the  Shawangunk  Mountains  of  eastern  New  York 
(20,  21).  Some  are  also  quarried  in  Pennsylvania,  North  Carolina, 
and  Virginia  (22).  The  material  adapted  to  millstones  is  very 
limited  in  extent.  Some  of  the  stone  is  also  cut  into  chasers,  used 
for  grinding  quartz  and  feldspar.  Owing  to  the  use  of  improved 
grinding  machinery  the  demand  for  millstones  has  fallen  off  greatly 
in  recent  years. 

Many  buhrstones  are  imported  from  France,  Belgium,  and  Ger- 
many. Those  from  the  first  two  localities  are  hard,  cellular  rocks, 

1  The  term  buhrstone  belongs  properly  to  those  millstones  made  of  a  chalce- 
donic  rock,  full  of  cavities,  some  of  them  representing  casts  of  shells. 

284 


PLATE  XXIX 


FIG.  1.  —  Grindstone  quarry,  Tippecanoe,  Ohio.     (J.  H.  Pratt,  photo.) 


FIG.  2.  —  Corundum  vein  between  peridotite  and  gneiss,  Corundum  Hill,  Gi 
(After  Pratt,  U.  S.  Geol.  Surv.,  Bull.  180.) 

(285) 


286 


ECONOMIC   GEOLOGY 


TABLE  SHOWING  ABRASIVES  OBTAINED  FROM  DIFFERENT  STATES  IN  1913 

AND  1914 


MILLSTONES 

§ 

fc 

o 

SCYTHESTONES 

GRINDSTONES 

PULPSTONES 

ROTTENSTONE 

GARNET 

EMERY 

DIAT.  EARTH 

TRIPOLI 

PUMICE 

Alabama.     .     .     . 

X 

Arkansas 

— 

X 

California    . 

— 

— 

— 

— 

— 



— 

— 

X 

— 

X 

Connecticut     .     . 

— 

— 

— 

— 

— 



— 

— 

X 

Georgia  .... 

— 

— 

— 

— 

— 



— 

— 

— 

lx 

Florida    .... 

— 

— 

— 

— 

— 



— 

— 

— 

1  X 

Illinois    .... 

— 

— 

— 

— 

— 



— 

— 

X 

Indiana  .... 

— 

X 

Kansas    .... 

— 

'  — 

— 

— 

— 



— 

— 

— 

— 

X 

Kentucky    .     .     . 

— 

X 

Maryland    . 

— 

—  . 

— 

— 

— 



— 

— 

X 

Massachusetts 

— 

— 

— 

— 

— 



— 

— 

2X 

Michigan     .     .     . 

— 

— 

X 

X 

Missouri 

— 

— 

— 

— 

— 



— 

—  • 

— 

X 

Nebraska     . 

— 

— 

— 

— 

— 



— 

— 

— 

—  . 

X 

Nevada  .... 

—  . 

— 

— 

— 

— 



— 

— 

X 

New  Hampshire   . 

— 

— 

X 

— 

— 



X 

New  York   . 

X 

— 

—  . 

— 

— 



X 

X 

X 

North  Carolina     . 

X 

— 

—  ; 

— 

— 



X 

Ohio  

— 

X 

X 

X 

X 

Oklahoma    .     .     . 

— 

— 

— 

— 

— 

. 

— 

— 

— 

lx 

Pennsylvania   .     . 

X 

— 

— 

— 

— 

2X 

Tennessee    .     .     . 

— 

— 

— 

— 

— 

— 

— 

— 

— 

lx 

— 

Utah  

— 

— 

— 

— 

—  . 

— 

— 

— 

— 

— 

1X 

Vermont      .     .     . 

— 

— 

X 

Virginia  .... 

X 

— 

— 

— 

— 

— 

— 

— 

2X 

Washington      .     . 

— 

— 

— 

— 

— 

— 

— 

— 

X 

West  Virginia  .     . 

— 

— 

— 

X 

1  Recorded  only  for  1913.         2  Recorded  only  for  1914. 

consisting  of  a  mixture  of  fine  quartz  particles  and  calcareous  mate- 
rial; but  the  German  buhrstone  is  basaltic  lava. 

Grindstones  (2,  13).  —  These  are  made  from  sandstones  of  homo- 
geneous texture  and  sufficient  cementing  material  to  hold  the  quartz 
grains  together,  but  not  enough  to  so  fill  the  pores  as  to  make  the 
rock  wear  smooth  under  use.  Most  of  the  grindstones  produced  in 
the  United  States  are  obtained  from  the  Berea  grit  of  Ohio  (PL 
XXIX,  Fig.  1)  and  Michigan,  certain  layers  of  which  are  highly 


ABRASIVES  287 

prized  for  this   purpose.     West  Virginia  also  contributes  to  the 
output. 

Pulpstones,  which  have  a  diameter  of  48  to  56  inches,  a  thickness 
of  16  to  26  inches,  and  a  weight  of  2300  to  4800  pounds,  are  a  thicker 
variety  of  grindstone.  They  are  used  for  grinding  wood  pulp  in 
paper  manufacture,  and  hence  have  to  withstand  continual  ex- 
posure to  hot  water.  On  account  of  their  superior  quality,  pulp- 
stones  from  Newcastle-upon-Tyne,  England,  supply  most  of  the 
American  demand;  but  it  is  probable  that  certain  beds  of  the  Ohio 
sandstones  will  be  found  suited  for  this  purpose  (2). 

Whetstones,  Oilstones  (2,  13,  17),  etc.  —  The  term  "  whetstone  '' 
includes  those  stones  used  for  sharpening  tools,  the  term  "  oilstone  " 
being  often  applied  when  oil  is  placed  on  the  stone  to  prevent  heat- 
ing and  clogging  of  the  pores  by  grains  of  steel.  The  stones  used 
for  making  whetstones  are  either  sedimentary  or  metamorphic  in 
character,  and  include  sandstone,  quartzite,  mica  schist,  and  novac- 
ulite.  The  stone  selected  will  naturally  vary  somewhat  with  the 
exact  use  to  which  it  is  to  be  put,  but  even  texture  and  compara- 
tively fine  grain  are  essentials.  A  small  amount  of  clayey  matter 
adds  to  the  fineness  of  grinding,  but  an  excess  lowers  the  abrasive 
efficiency  of  the  stone.  In  the  schists  used,  abrasive  action  is  due 
to  the  grains  of  quartz,  or  sometimes  garnet,  which  are  embedded 
among  the  fine-grained  scales  of  mica. 

Rocks  suitable  for  whetstone  manufacture  are  found  in  many 
states,  especially  east  of  the  Mississippi  (2,  13),  but,  on  account  of 
keen  competition  and  limited  demand,  only  the  better  grades  from 
the  best-located  deposits  are  employed.  Most  of  the  supply  is 
therefore  obtained  from  a  few  states,  especially  Arkansas,  Indiana, 
Ohio,  New  York,  Vermont,  and  New  Hampshire. 

Among  the  whetstones  quarried  in  the  United  States,  the  Hindo- 
stan  or  Orange  stone  of  Indiana  and  the  Deerlick  oilstone  of  Ohio  are 
much  used  for  oilstones.  Scythestones  are  made  from  schistose  rock 
in  Grafton  County,  New  Hampshire,  and  Orleans  County,  Vermont. 

At  Pike  Station,  N.  H.  (PL  XXVI,  Fig.  2),  the  raw  material 
quarried  for  scythestones  is  a  fine-grained,  thinly  laminated,  mica- 
ceous sandstone,  whose  quartz  grains  occur  in  definite  layers,  separ- 
ated by  thin  layers  of  mica  flakes.  Those  portions  of  the  rock 
in  which  the  quartz  grains  are  coarse  or  irregularly  disposed,  as  well 
as  argillaceous  portions,  are  unfit  for  abrasive  purposes.1 

The  novaculite  quarried  in  Garland  and  Saline  counties,  Arkan- 
sas (17),  represents  a  unique  type,  much  prized  for  high-grade 

1  Min.  Res.,  U.  S.  Geol.  Surv.,  1908. 


288 


ECONOMIC   GEOLOGY 


oilstones  for  sharpening  small  tools,  and  in  demand  both  at  home 
and  abroad.     It  is  an  extremely  fine-grained  sandstone  made  up  of 


FIG.  94.  —  North-south  section  through  Missouri  and  Statehouse  Mountains  show- 
ing folded  character  of  novaculite  and  slate-bearing  formations  of  Arkansas,  a. 
Bigfork  chert;  b.  Pclk  Creek  shale;  c.  Missouri  Mountain  slate;  d.  Arkansas 
novaculite;  e.  Stanley  shale.  (After  Purdue,  Ark.  GeoL  Sun.,  1909.) 

finely  fragmental  quartz  grains,  visible  under  the  microscope.  The 
rock  is  chertlike  in  superficial  appearance  and  has  a  conchoidal 
fracture.  While  the  deposits,  which  are  stratified,  have  a  total 
thickness  of  over  500  feet,  the  commercial  novaculite  is  found  only 
in  thin  beds  varying  from  a  few  inches  to  15  feet  in  thickness.  The 
beds  have  a  steep  dip  (PL  XXX  and  Fig.  94),  and  are  cut  by  sev- 
eral series  of  joints,  which  greatly  interfere  with  the  extraction  of 
large  blocks,  and  sometimes  even  with  small  ones.  There  are  also 
structural  irregularities  and  almost  invisible  flaws,  so  that  much 
waste  is  caused  in  quarrying  the  rock.  The  rock  has  been  variously 
regarded  as  a  metamorphosed  chert,  a  siliceous  silt,  or  a  silicified 
limestone. 

Pumice  and  Volcanic  Ash.  —  The  term  "  pumice/'  as  used  in 
the  geological  sense,  refers  to  the  light  spongy  pieces  of  lava,  whose 
peculiar  texture  is  due  to  the  rapid  and  violent  escape  of  steam 
from  the  molten  lava.  It  is  put  on  the  market  either  in  lump  form, 

or  ground  to  powder,  or  in  com- 
pressed cakes  of  the  ground-up 
material.  In  the  commercial 
sense  the  term  "  pumice  "  in- 
cludes volcanic  ash  (Fig.  95)  as 
well  as  true  pumice. 

Most  of  the  pumice  used  in 
the  United  States  is  obtained 
from  the  island  of  Lipari,  north 
of  Sicily.  The  stone,  after  being 
freed  from  the  volcanic  ash  with 
which  it  is  mixed,  is  sorted  ac- 
Fio.  95.— Volcanic  ash  from  Madison  cording  tocolor,  weight,  and  size. 

County,  Mont.     (After  J.  P.  Rowe.)          ,     ,         . ,  .      •.•         A>  i     + 

before  it  is  shipped  to  market. 


PLATE  XXX.— View  in  Arkansas  novaculite  quarry.    (Photo,  loaned  by  Pike  Me 

facturing  Co.) 

(289) 


290  ECONOMIC   GEOLOGY 

Deposits  of  volcanic  ash  are  abundant  in  many  western  states, 
for  example,  in  Nebraska  (10),  Utah  (13),  Montana  (14),  Oregon 
(12),  Wyoming  (ll),  Colorado  (15),  etc.,  but  owing  to  their  inacces- 
sibility these  materials  cannot  compete  with  Lipari  pumice,  which 
is  imported  as  ballast,  and  sells  in  its  prepared  form  for  2  to  2j  cents 
per  pound.  The  pumice  produced  in  the  United  States  in  1913 
came  from  Kansas,  Utah  and  Nebraska.  The  deposits  are  very 
abundant  in  the  last  named  state,  as  B arbour  remarks  that  nearly 
the  whole  of  it  is  underlain  by  pumice  beds  as  far  east  as  Omaha. 

Diatomaceous  Earth.1  —  This  material  has  been  used  to  some 
extent  for  abrasive  purposes,  either  in  the  form  of  polishing 
powder  or  in  scouring  soap.  Since  it  has  many  other  and  more 
important  possible  applications,  it  is  described  separately  on  a 
later  page. 

Tripoli.  (See  p.  412.)  —  Some  of  the  Missouri  tripoli  is  ground 
and  sold  as  tripoli  flour,  whose  value  f.o.b.  is  $6-$7  per  ton.  This 
flour  is  employed  as  an  abrasive  for  general  polishing,  burnishing, 
and  buffing,  as  well  as  an  ingredient  of  scouring  soaps. 

The  so-called  "  silica  "  obtained  in  Union  County,  Illinois,  is 
similar  to  tripoli,  and  may  have  had  the  same  origin. 

Both  of  these  run  high  in  silica,  and  in  that  respect  are  different 
from  a  so-called  tripoli,  obtained  in  Johnson  County,  Tenn.,  and 
representing  a  leached  Cambrian  limestone.  It  carries  about  68 
per  cent  silica  (Ref.  p.  414). 

Crystalline  Quartz  (2,  13).  —  Some  of  the  vein  quartz  quarried 
in  the  United  States,  and  also  quartzite,  is  pulverized  and  used  for 
abrasive  purposes.  Considerable  quartz  sand  is  employed  by 
stone  cutters  as  an  abrasive  in  sawing  stone,  and  a  small  quantity 
is  utilized  in  making  sandpaper.  (See  further,  p.  390.) 

Feldspar  (13).  —  This  also  is  used  to  a  small  extent  for  abrasive 
purposes,  but  since  it  has  other  and  more  important  uses  it  is  dis- 
cussed separately  on  p.  321. 

Garnet  (13,  16).  —  The  garnet  group  includes  several  mineral 
species  which  are  essentially  silicates  of  alumina  with  iron  or  lime, 
magnesia,  manganese,  and  chromium.  They  crystallize  in  the  iso- 
metric system,  have  a  hardness  of  6.5  to  7.5  and  a  specific  gravity 
of  3.55  to  4.30. — Their  color  is  variable,  but  commonly  a  shade 
of  red  or  brown.  The  two  commonest  species  are  Almandite 
[Fe3Al2(SiO4)3]  and  Grossularite  [Ca3Al2(Si04)3]. 

1  Infusorial  earth  and  tripoli  are  terms  sometimes  applied  to  Diatomaceous 
earth.  Both  are  incorrect. 


ABRASIVES  291 

Garnet  is  a  common  mineral  in  many  metamorphic  rocks,  and 
though  ordinarily  a  subordinate  constituent  of  these,  it  may  in 
some  cases  become  the  chief  one. 

Garnet  is  of  value  as  an  abrasive  because  of  its  hardness,  tough- 
ness and  cleavage.  The  best  material  is  that  which  is  well  crys- 
tallized and  relatively  free  from  impurities,  for  it  has  greater 
strength  and  stands  up  better  under  conditions  of  service  than 
finely  granular  material,  or  that  containing  inclusions  of  other 
minerals.  The  common  impurities  found  in  garnet  are  horn- 
blende, chlorite,  mica,  and  pyroxene.  The  parting  or  imperfect 
cleavage  which  garnet  possesses  causes  it  to  break  with  smooth 
surfaces  and  sharp  edges,  the  latter  adding  to  its  abrasive 
value. 

Although  garnet  is  a  common  mineral  in  many  metamorphic 
rocks,  especially  gneisses  and  schists,  few  deposits  of  economic 
value  are  known,  and  in  the  United  States  the  most  productive 
deposits  are  found  in  the  Adirondacks,  while  others  are  worked 
in  New  Hampshire  and  North  Carolina. 

New  York  (16,  16a) .  —  The  garnet  industry  is  an  important  one 
in  the  Adirondack  region,  a  steady  production  having  come  from 
Warren  and  Essex  Counties.  The  garnet,  which  is  Almandite, 
may  occur  in  several  different  ways,  viz.:  1.  As  crystals  or  grains 
in  Grenville  gneisses,  and  representing  a  crystallization  product 
of  the  metamorphism  of  sediments;  2.  As  distinct  crystals  in 
intrusive  rocks.  3.  As  large,  more  or  less  rounded  masses  with 
distinct  hornblende  reaction  rims,  occurring  in  long,  lens-like 
inclusions  of  Grenville  hornblende  gneiss  in  syenite  or  granite; 
4.  As  more  or  less  distinct  crystals,  without  hornblende  rims,  in 
a  certain  special  basic  syenite  like  an  acidic  diorite-like  rock. 

At  the  largest  mine  the  garnets  form  7  to  8  per  cent  of  the 
gneiss  mined.  The  rock  is  crushed,  and  the  garnet  concentrated 
by  jigs  and  pneumatic  separators. 

Other  Localities.  —  Garnet  is  also  produced  in  New  Hampshire 
(I5o)  and  North  Carolina.  In  the  former  state,  the  rock  quarried 
at  Wilmot  consists  of  garnet,  biotite,  quartz  and  albite,  of  which 
the  first  named  forms  about  60  per  cent. 

Some  garnet  has  been  imported  from  Spain,  and  is  said  to  be 
obtained  by  washing  the  sands  of  certain  streams  in  the  province 
of  Almeria. 

Uses.  —  Garnet  is  used  in  the  manufacture  of  garnet  paper, 
being  a  valuable  abrasive  for  leather  and  wood.  It  has  also  been 


292 


ECONOMIC  GEOLOGY 


employed  in  polishing  and  grinding  brass.  Attempts  have  been 
made  to  use  it  as  a  substitute  for  corundum  in  the  manufacture  of 
emery  wheels,  for,  although  softer,  it  possesses  the  advantage  of 
having  a  splintery  fracture,  which  prevents  it  from  wearing 
smooth. 

Corundum  and  Emery  (3-9).  —  Corundum  (A1203)  is,  next  to 
diamond,  the  hardest  of  the  natural  abrasives  known,  having  a 
hardness  of  9,  but  varying  slightly  from  this. 

Its  fracture  is  irregular  to  conchoidal,  and  gives  a  good  cutting 
surface,  but  the  presence  of  parting  planes  decreases  its  value.  A 
specific  gravity  of  4  helps  to  distinguish  it  from  other  light-colored 
minerals  found  in  the  corundum  regions.  Corundum  shows  a 
variable  behavior  when  heated,  some  forms  crumbling  when  ex- 
posed to  a  high  temperature.  Such  kinds  are  worthless  for  the 
manufacture  of  emery  wheels,  all  of  which  must  be  fired  in  order  to 
fuse  the  clay  bond  used  in  their  manufacture. 

Nearly  all  corundum  analyses  show  SiO2,  Fe203,  and  H20,  and  it 
must  be  remembered  that  in  analyses  of  commercial  corundum 
the  alumina  percentage  does  not  indicate  the  quantity  of  corundum 
present,  as  some  of  it  may  belong  to  aluminous  silicates. 

The  following  analyses  represent  selected  rather  than  commercial 
samples:  — 

ANALYSES  OF  CORUNDUM 


A1203 

Fe203 

SiO2 

H,O 

INS. 
RES. 

TOTAL 

Hastings  Co     Ont 

9692 

243 

1  36 

100.71 

Corundum  Hill,  N.  Ca.   .     .     . 

98.79 

.75 

.90 

.78 

101.22 

Laurel  Creek  Mine,  Ga.   .     .     . 
Ruby  from  India    

95.51 
97.32 

.88 
1.09 

1.45 
1.21 

.74 

— 

98.58 
99.62 

Sapphire  from  India   .... 

97.51 

1.89 

.80 

— 

— 

100.20 

Corundum  may  occur  in  masses,  crystals,  or  irregular  grains. 
It  is  found  in  both  igneous  and  metamorphic  rocks,  as  well  as  in 
alluvial  deposits  derived  from  them,  although  the  last  supply  but 
little  abrasive  corundum. 

Corundum  forms  a  primary  constituent  (sometimes  an  important 
one)  of  feldspathic  igneous  rocks,  both  high  and  low  in  silica.  It 
is  found  in  granite,  syenite,  nephelite-syenite,  and  coarse  pegma- 
tites. It  is  also  known  to  occur  in  crystalline  schists  and  meta- 
morphosed limestones. 


ABRASIVES 


293 


A  number  of  other  minerals  may  be  associated  with  it  as  follows  (5): 
Associated  minerals. 

In  gneiss  and  granite:  Besides  essentials,  garnet  magnetite,  pyritet 
zircon,  rarely  monazite  and  sodalite. 

In  peridotites  and  other  basic  rocks:  Olivine,  magnesian  amphibole, 
pyroxenes,  rarely  plagioclase;  chromite  and  spinel,  accessory  primaries. 

In  contact  zones:  Corundum,  biotite,  muscovite,  garnet,  staurolite, 
tourmaline,  rutile,  etc. 

In  regionally  metamorphosed  rocks:  biotite,  muscovite,  amphibole,  silli- 
manite,  cyanite. 

Distribution.  —  With  the  exception  of  a  few  localities  in  Mon- 
tana, two  in  Colorado,  one  in  Idaho,  and  one  or  two  in  California, 
all  the  known  United 
States  occurrences 
are  confined  to  the 
Appalachian  region, 
the  commercially 
valuable  deposits  for 
abrasive  purposes 
being  found  in  a  belt 
of  basic  magnesian 
rocks,  extending 
from  Massachusetts 
to  Alabama. 
These  rocks  reach 
their  greatest  de- 
velopment in  North 


_.  _ 


FIG.  96.  —  Section  showing  occurrence  of  corundum 
around  border  of  dunite  mass.  (After  Pratt, 
U.  S.  GeoL  Sun.,  Bull.  180.) 


Carolina      (5)      and 

Georgia    (3)  .     Most 

of  the  corundum  is 

found  there,  in  peridotite,  especially  near  its   contact  with   the 

surrounding  gneiss. 

It  is  believed  that  the  corundum  which  was  one  of  the  earliest 
minerals  to  crystallize  out  from  the  cooling  peridotite  was  concen- 
trated around  the  borders  of  the  mass  by  convection  currents.  This 
zone  of  corundum  sent  off  tongues  toward  the  interior  of  the  mass, 
and  now  that  erosion  has  removed  the  main  zone  of  corundum, 
these  tongues  remain  as  apparently  separate  veins  within  the  peri- 
dotite (Fig.  96). 

In  North  Carolina  (5)  the  greatest  development  of  corundum  is  in  a  belt 
in  Macon  County.  Some  is  also  found  east  of  the  Blue  Ridge.  Georgia 
(3)  contains  scattered  deposits,  the  most  important  being  at  Pine  Mountain, 
Rabun  County.  Some  mining  has  been  done  in  South  Carolina  and  Geor- 


294 


ECONOMIC   GEOLOGY 


gia,  and  deposits  in  garnetiferous  mica  schists  cut  by  granite  have  been 
recorded  from  Patrick  County,  Virginia  (9). 

No  corundum  production  is  recorded  in  the  United  States  since  1906. 

Corundum  in  Canada  (2a) .  —  Important  deposits  of  this  mineral 
are  worked  at  Craigmont,  Ontario.  The  northern  part  of  this 
hill  is  composed  of  granite  gneiss  of  the  Laurentian  batholith, 
which  appears  to  merge  into  the  overlying  corundum-bearing 
series  that  forms  the  summit  and  southern  slope.  This  latter 
series  is  a  complex  of  different  but  closely  related  rock  types 
representing  differentiation  products  of  one  highly  alkaline  and 
aluminous  magma,  containing  nepheline.  These  rocks  are  inter- 
sected by  syenite  pegmatite,  which  contains  the  largest  and  most 
abundant  crystals  and  masses  of  corundum.  These  dykes  some- 
times attain  a  width  of  18  feet,  and  usually  run  parallel  with  the 
foliation  of  the  series. 

Emery ./ —  This  is  a  mechanical  mixture  of  corundum,  magnetite 
or  hematite,  and  sometimes  spinel.  Peekskill,  New  York  (6-8),  is 
now  the  most  important  sources  of  production,  Massachusetts 
having  discontinued. 

At  the  former  locality,  the  deposits  which  lie  southeast  of  the  town, 
and  were  first  opened  for  iron  ore,  occur  along  the  contact  of  basic  intrusions 
belonging  to  the  gabbro  series.  The  emery  deposits,  according  to  G.  H. 
Williams,  are  simply  segregations  of  the  basic  oxides  in  the  norite,  and  the 
ore  is  made  up  of  corundum,  magnetite,  and  hercynite  (an  iron-aluminum- 
spinel).  In  some  specimens  the  corundum  forms  over  50  per  cent  of  the 
mass,  while  in  others  the  hercynite  may  make  up  nearly  100  per  cent  of  it. 
The  Peekskill  material  is  very  serviceable  when  made  into  wheels  with  a 
bond.  The  following  are  analyses  of  it. 


I 

II 

III 

AUO, 

20  95 

38  78 

46  53 

si&,. 

13  97 

TiO,  . 

4  15 

62 

51 

Fe      .    .    . 

4032 

Fe,O3     . 

24  35 

32  31 

MgO 

7  92 

9  43 

P,O3  

tr 

tr 

Si  residue  . 

11  19 

2  42 

Fe,O,. 

17  37 

8  98 

02 

01 

I.  Am.  Chemist,  1874,  4:  321.    II  and  III.  A.  J.  S.,  March,  1887,  p.  197. 

At  Chester,  Massachusetts  (13),  the  emery  occurs  in  a  local  widening 
of  a  belt  of  amphibolite  schists,  and  forms  a  vein  traceable  for  nearly  five 
miles.  The  emery-bearing  vein  varies  in  width  from  a  few  feet  up  to  10 


ABRASIVES  2P5 

or  12  feet,  while  the  emery  streak  in  it  averages  about  6  feet,  it  being  bordered 
on  both  sides  by  chlorite  seams.  The  emery  is  in  pockets,  but  these  are 
traceable  by  a  small  vein  of  chlorite.  The  Massachusetts  output  has  been 
diminishing  and  none  has  been  reported  since  1912. 

After  mining,  both  corundum  and  emery  need  to  be  cleaned  and 
concentrated  by  special  mechanical  processes.  The  chief  use  of 
this  material  is  as  an  abrasive,  and  for  this  purpose  it  is  used  in  the 
form  of  wheels  and  blocks,  emery  paper,  and  powder. 

Practically  all  the  corundum  and  emery  used  in  the  United 
States  is  imported.  The  emery  is  imported  crude  as  ballast  from 
Turkey  and  Greece.  Corundum  is  imported  mainly  from  Canada 
in  pulverized  form. 

Diamonds.  —  Black  diamonds,  known  as  borts  and  carbonados, 
which  are  of  no  value  for  gem  purposes,  are  much  sought  after  for 
use  in  drilling,  being  set  in  the  end  of  the  cylindrical  drill  tube. 
They  are  often  of  rounded  form,  translucent  to  opaque,  and  lack 
the  cleavage  possessed  by  the  gem  diamonds.  Brazil,  Africa, 
Borneo  and  India  serve  as  sources  of  supply,  but  the  first-named 
country  is  said  to  yield  the  best  ones.  The  ordinary  sizes  for  drills 
weigh  from  £  to  1  carat,  but  in  special  cases  pieces  weighing  4  to  6 
carats  are  used.  The  price  ranges  from  $50  to  $75  per  carat. 

Diamond  powder  is  also  used  as  an  abrasive  for  cutting  other 
diamonds,  gems,  glass,  and  hard  materials  which  cannot  be  cut  by 
softer  and  cheaper  substances. 

Pebbles  for  Grinding  (23-25).  —  These  are  used  for  grinding 
minerals,  ores,  cement  clinker,  etc.,  and  those  employed  in  the 
United  States  have  been  chiefly  flint  pebbles  obtained  from  the 
chalk  formations  of  Denmark  and  France,  but  not  a  few  have  been 
imported  from  other  foreign  countries.  The  value  of  flint  pebbles 
lies  in  their  hardness  and  uniform  character;  moreover,  they  con- 
tain little  else  but  silica,  and  hence  there  is  little  danger  of  the 
material  worn  off  contaminating  the  ground  product,  as  for 
example  in  grinding  feldspar,  which  must  be  free  from  iron 
oxide. 

The  decrease  in  foreign  supply,  due  to  the  European  war,  has 
stimulated  search  for  domestic  sources,  of  supply  with  some 
results.  Pebbles  of  granite  and  quartzite  have  been  imported 
into  the  United  States  from  Newfoundland  and  Ontario  for  some 
time,  and  similar  ones  could  be  found  here.  Stream  pebbles  of 
quartz  have  been  tried  in  California  gold  mills;  dense  silicified 


296 


ECONOMIC   GEOLOGY 


rhyolite  has  given  satisfactory  results  in  some  of  the  metallurgical 
mills  of  Nevada,  and  basalt  has  been  tried  in  Oregon. 

Artificial  Abrasives.  —  Several  artificial  abrasives  are  now 
much  manufactured.  Prominent  among  these  is  carborundum, 
which  is  produced  by  fusion  in  the  electric  furnace  of  a  mixture 
of  silica,  coke,  and  sawdust;  the  reaction  beingSi02+3  C  =  CSi 
+2  CO.  The  sawdust  is  added  to  give  porosity  to  the  mixture. 
Other  forms  of  carborundum  are  aloxite  and  samite. 

Artificial  corundum  or  alundum,  whose  introduction  is  of  more 
recent  date,  is  made  by  fusing  bauxite  in  the  electric  furnace.  It  is 
put  on  the  market  in  the  form  of  wheels,  etc.,  while  carborundum 
is  either  made  into  wheels  or  sold  in  powdered  form.  Boro- 
carbone  is  similar  to  alundum. 

Production  of  Abrasives.  —  The  value  of  the  abrasives  pro- 
duced in  the  United  States  during  the  last  five  years,  together 
with  the  imports  and  artificial  abrasives,  was  as  follows: — 

VALUE  OF  ALL  ABRASIVE  MATERIALS  CONSUMED  IN  THE  UNITED  STATES, 

1910-1914 


KIND  OF  ABRASIVE 

1910 

1911 

1912 

1913 

1914 

Millstones     
Grindstones  and  pulpstones 
Oilstones  and  scythestones 

$28,217 
796,294 
228,694 
15  077 

$40,069 
907,316 
214,991 

6  778 

$71,414 
916,339 
232,218 
6  652 

$56,163 
855,627 
207,352 

4  785 

$43,316 
689,344 
167,948 
2  425 

Garnet     

113,574 

121,748 

163,237 

183  422 

145  510 

Abrasive  quartz  and  feldspar 
Infusorial  earth  and  tripoli 

130,006 
94  943 

i 
147,462 
88  399 

i 
125,446 
86  687 

285,821 
55  408 

i 
142,428 
59  172 

Total                .... 

$1  406,805 

$1,526  763 

$1  601  993 

$1  648  578 

$1  200  143 

Artificial  abrasives     .     . 
Imports  

1,604,030 
977,718 

1,493,040 
815,854 

1,747,120 
898,892 

2,017,458 
916,913 

1,685,410 
728,710 

Grand  total    .... 

$3,988,553 

$3,835,657 

$4,248,005 

$4,582,949 

$3,614,263 

1  Value  of  abrasive  quartz  and  feldspar  is  not  available  as  it  is  included  with 
other  uses  of  those  minerals. 

REFERENCES    ON   ABRASIVES 

GENERAL:  1.  King,  Ga.  Geol.  Surv.,  Bull.  2:  119,  1894.  2.  Pratt,  U.  S. 
Geol.  Surv.,  Min.  Res.,  1900:  787,  1901.  —  Corundum  and  Emery: 
2a.  Barlow,  Can.  Geol.  Surv.,  Mem.  57,  1915.  (Canada  and  general.) 
Also  papers  by  Miller,  Coleman  and  others  in  Ont.  Bur.  Mines,  VII, 
Pt.  3  and  VIII,  Pt.  2.  (Ont.  and  technology.)  3.  King,  Ga.  Geol. 
Surv.,  Bull.  2:  73,  1894.  (Georgia.)  4.  Pratt,  U.  S.  Geol. 
Surv.,  Bull.  269,  1906.  (United  States.)  5.  Pratt  and  Lewis, 
N.  Ca.  Geol.  Surv.,  I,  1905.  (Corundum,  N.  Ca.)  6.  Magnus,  N.  Y. 
State  Geologist,  23d  Ann.  Kept.:  163,  1904.  (N.  Y.  emery.) 
7.  Williams,  G.  H.,  Amer.  Jour.  Sci.,  iii,  XXXIII:  194,  1887.  (N.  Y. 
emery.)  8.  Nevius,  N.  Y.  State  Mus.,  53d  Kept.,  1901.  (New  York 


ABRASIVES  297 

emery.)  9.  Watson,  Min.  Res.  Va.,  1907.  (Va.  corundum.)  9a. 
Sloane,  S.  Ca.  Geol.  Surv.,  Ser.  IV,  Bull.  2:  150,  1908.  (S.  Ca.  cor- 
undum.)—  Diatomaceous  Earth:  See  references  on  p.  318.  —  Pumice 
and  volcanic  ash:  10.  Harbour,  Neb.  Geol.  Surv.,  I:  214,  1903.  10a. 
Buttram,  Okla.  Geol.  Surv.,  Bull.  13,  1914.  (Okla.)  11.  Darton 
and  Siebenthal,  U.  S.  Geol.  Surv.,  Bull.  364:  65,  1907.  (Wyoming.) 
12.  Diller,  U.  S.  Geol.  Surv.,  Prof.  Pap.  3:  40,  1902.  (Oregon.)  13. 
Merrill,  G.  P.,  Non-metallic  Minerals,  New  York,  1904.  13a.  Pardee 
and  Hewett,  Min.  Res.  Ore.,  I,  No.  6:  72,  1914.  (Vole,  ash,  Ore.) 

14.  Rowe,  Bull.  Univ.  Mont.,  No.  17,  Geol.  Ser.  No.  1, 1894.     (Montana.) 

15.  Woolsey,   U.   S.   Geol.  Surv.,   Bull.  285:    476,   1906.     (Colorado.) 
-Garnet:    15a.  U.  S.  Geol.  Surv.,  Min.  Res.,  1913:    266,  1914.     16. 
Newland,  N.  Y.  State  Mus.,  Bull.  102:  70,  1906.     (New  York.)     Also 
Ref.   13.     16a.  Miller,   N.  Y.  State  Mus.,   Bull.   164:    95,   1913,   and 
Econ.    Geol.   VII:    493,    1912.     (N.   Y.)  —  Whetstones,    Grindstones, 
and  Millstones:     17.  Griswold,   Ark.   Geol.  Surv.,  Ann.  Rept.,   1890, 
III,    1892.     (Ark.    novaculite.)     18.  Grimsley,    W.    Va.    Geol.    Surv. 
IV:     375,    1909.     (Grindstones.)     19.  Kindle,    Ind.    Dept.    Geol.    and 
Nat.  Res.,  20th  Ann.  Rept.:    329,   1896.     (Indiana.)     20.  Nason,  N. 
Y.  State  Geol.,  13th  Ann.  Rept.,  I:  373,  1894.     (N.  Y.)     21.  Newland, 
N.  Y.  State  Museum,  Bull.  102:    110,   1906.     (N.  Y.)     22.  Watson, 
Min.  Res.  Va.:    401,  1907.     (Grindstones.)  —  Tripoli:    See  references, 
p.  414. —  Pebbles:   23.  Carpenter,  Min.  and  Sci.  Press,  Jan.  23,  1915. 
(Danish    and    substitutes.)     24.  Eckel,    Ibid.,   Jan.    16,    1915.     (Tube 
mill  pebbles.)     25.  Anon.,  Ibid.,  Feb.  13,  1915.    (Substitutes  for  Danish 
pebbles.) 


CHAPTER  X 
MINOR  MINERALS.    ASBESTOS 

Asbestos  Minerals  (i,  13).  —  The  minerals  which  have  been 
mined  and  sold  under  this  name  include:  Chrysotile,  the  fibrous 
form  of  serpentine  (H4Mg3Si2Og),  Actinolite  [CaCMgFe^SiOa)*], 
and  Anthophyllite  (MgFe)SiO3.  Crocidolite  (NaFeSi2O6 •  FeSi03) 
is  also  mentioned  by  some. 

The  following  table  gives  the  chemical  composition  of  the 
different  ones: 


ANALYSES  OF  ASBESTOS  MINERALS 


I 

II 

III 

IV 

V 

VI 

VII 

VIII 

SiO2  .     .    V    . 
A1203      . 
FeO  .     .    .     . 
Fe2O3     .     .     - 
MgO      ... 
CaO  .     .     .     . 
Na^O      .     .     . 
Ignition      .     . 

40.30 

2.27 
.87 

43.37 
13.72 

39.05 
3.67 
2.41 

40.07 
14.48 

40.87 
.90 
2.81 

41.50 
13.55 

55.81 
1.66 
6.81 

21.09 
12.74 

1.81 

61.82 
1.12 
6.55 

23.98 
1.63 

57.12 
.75 
6.36 

29.44 
5.47 

52.11 
1.01 
16.75 
20.62 
1.77 

6.16 
1.58 

39.97 

J7.27 

40.78 
.50 

12.51 

5.45 

I.  Chrysotile,    Italy;  V.  Actinolite,  Hastings  County,  Que.; 

II.  Chrysotile,  Thetford,  Que.;         VI.  Anthophyllite,  Sail  Mtn.,  Ga.; 

III.  Chrysotile,  Broughton,  Que.;    VII.  Crocidolite,  S.  Afr.; 

IV.  Amphibole,  Roanoke  County, 

Va.;  VIII.  Chrysotile,  Vermont. 

Mode  of  Occurrence.  —  Asbestos  may  occur  in  three  dif- 
ferent ways,  viz. : 

1.  Cross  fiber  found  in  fissures  with  the  fibers  transverse  to 
the  wall.  It  consists  usually  of  chrysotile  and  rarely  of  antho- 
phyllite. 

298 


MINOR  MINERALS 


299 


2.  Slip  fiber    lying  in  slipping  planes    with  the  fibers  parallel 
to  the  walls.     It  may  be  either  chrysotile  or  amphibole. 

3.  Mass  fiber  with  the  fiber  occurring  in  bundles  or  groups. 
This  is  always  anthophyllite. 

Comparison  of  Types.  —  Of  the  three  asbestos  minerals, 
chrysotile  is  the  most  important  and  anthophyllite  next.  The 
commercial  value  of  asbestos  depends  on  the  fineness,  length, 
flexibility,  and  strength  of  its  fiber.  Chrysotile  asbestos  is 


FIG.  97.  —  Map  showing  asbestos  districts  of  the  United  States.     (After  Diller, 
U.  S.  GeoL  Surv.,  Min.  Res.  1913.) 

1.  Lowell,  chrysotile;  2.  Thetford,  Que.,  chrysotile;  3.  Rocky  Mount,  Va., 
Amphibole  slip  fiber;  4.  Sail  Mountain,  Ga.,  anthophyllite;  5.  Llano,  Tex. 
amphibole;  6.  Casper  Mountain,  Wyo.,  chrysotile;  7.  Grand  Canyon,  and  Globe, 
Ariz.,  chrysotile;  8.  Kamiah,  Ido.,  anthophyllite;  9.  Towle,  Calif.,  amphibole. 

generally  taken  as  the  standard.  Anthophyllite  equals  it  in 
resistance  to  acid,  heat,  and  insulating  properties,  but  is  far 
inferior  in  regard  to  flexibility,  fineness  of  fiber  and  tensile  strength. 
Crocidolite  is  inferior  to  chrysotile  in  its  fire-resisting  properties, 
but  equals  it  in  other  respects. 

Anthophyllite  because  of  its  mode  of  occurrence  is  cheaper  to 
mine  than  chrysotile,  since  the  latter  forms  but  a  small  per- 
centage of  the  entire  rock  mass,  and  has  to  be  crushed  and  freed 
from  impurities.  Hopkins  gives  the  Canadian  extraction  as 
6.45  per  cent  and  that  of  Georgia  as  90  to  95  per  cent. 


300  ECONOMIC  GEOLOGY 

Distribution  in  the  United  States.  —  The  ancient  crystalline 
rocks  in  which  the  famous  Quebec  deposits  occur,  extend 
southwest  ward  through  the  eastern  states,  as  far  as  Alabama, 
and  while  a  number  of  small  deposits  of  asbestos  are  known, 
yet  nowhere  are  there  any  large  ones,  moreover,  most  of  the 
deposits  are  of  the  amphibole  type. 

Vermont  (8,  9) .  —  The  only  chrysotile  deposit  worked  in  the 
eastern  belt  is  in  Lamoille  and  Orleans  counties,  Vermont,  where 
the  material  is  found  occupying  a  rather  limited  area  in  a  large 
serpentine  area  (9) .  Two  types  of  chrysotile  are  found,  one  f orm- 


FIG.  98.  —  Asbestos  vein  in  serpentine.      (Photo,  by  G.  P.  Merrill.') 

ing  branching  veins  similar  in  character  and  quality  to  the  Cana- 
dian fiber,  the  other,  of  inferior  quality,  occurring  as  short  fibers  on 
slickensided  surfaces.  In  1908  a  mill  was  erected  near  Lowell, 
Vermont,  for  separating  the  fiber,  but  the  district  had  up  to  1913 
not  entered  the  list  of  steady  producers. 

Georgia  (4). — Sail  Mountain,  Georgia,  has  been  the  main 
source  of  supply  of  asbestos  in  the  United  States  for  some  years. 
The  anthophyllite  forms  lens-shaped  masses  in  peridotites  and 
pyroxenites,  which  are  associated  with  pre-Cambrian  gneisses, 
the  largest  lens  exploited  being  70  by  50  by  50  feet.  The  fibers 
are  1J  inches  or  less  in  length,  but  break  into  shreds  of  J  to  TV 
inch.  Pyrite,  magnetite,  talc,  calcite  and  dolomite  are  the  im- 


MINOR  MINERALS 


301 


purities.  It  is  supposed  that  the  anthophyllite  has  been  formed 
by  the  alteration  of  olivine  and  enstatite  of  the  igneous  rocks. 
By  hydration  and  oxidation  both  the  anthophyllite  and  any 
unaltered  olivine  may  be  converted  into  serpentine,  and  the  latter 
partly  into  talc. 

The  rock  is  crushed,  fiberized  and  screened,  the  product  being 
used  chiefly  as  a  cement  for  boiler  covering. 


FIG.   99. —  Geologic  map  of  Vermont  asbestos  area.     {After  Marsters,  Geol.  Soc. 
Amer.,  Bull  XVI,  1905.) 

Virginia  (2,  16). — Amphibole  asbestos  is  found  in  slip-fiber  veins  near 
Bedford,  Va.  The  prevailing  rock,  which  consists  of  hornblende  and  olivine, 
or  in  some  cases  pyroxene  and  olivine,  is  cut  by  occasional  shear  planes 
along  which  the  slip  fiber  has  developed. 

Arizona  (2).  —  Asbestos  was  discovered  about  25  miles  northeast  of 
Globe  in  1913.  It  forms  cross-fiber  veins  in  limestone,  overlying  diabase, 
the  higher-grade  veins  being  associated  with  a  diabase  dike. 

Somewhat  similar  is  the  occurrence  in  the  Grand  Canon  of  the  Colorado 
River,  near  Grand  View,  where  the  asbestos  forms  veins  in  a  serpentinous 
layer,  enclosed  in  limestone,  not  far  from  a  diabase  sill.  Diller  has  sug- 
gested that  the  serpentine  is  derived  from  some  mineral  in  the  limestone, 


302 


ECONOMIC  GEOLOGY 


while  the  asbestos  veins  post-date  the  serpentine,  and  may  represent  a  phase 
of  contact  metamorphism. 

Idaho  (2).  —  Near  Kamiah,  the  anthophyllite  asbestos  forms  ledges, 
within  mica  schist,  and  may  represent  an  altered  intrusive.  It  is  shipped 
to  Spokane,  Wash.,  where  it  is  sawed  up  and  also  ground. 

Wyoming  (2).  —  South  and  southeast  of  Casper  are  pre-Cambrian  in- 
trusives  consisting  of  hornblende  schist,  diorite,  granite  and  serpentine, 
the  last-named  being  much  crushed  and  sheared,  and  containing  both  cross 
and  slip-fiber  veins  of  chrysotile. 


Precambrian 


|         |  Palaeozoic 


Asbestos  and 
Chromite  Rocks 


SCAtt  OF  MILES 

FIG.  100.  —  Map  of  Quebec  asbestos  area.     (After  Dresser,  Can.  Min.  Inst., 

Trans.  XII.) 

Quebec,  Canada.  —  The  main  source  of  the  world's  supply 
is  obtained  from  southern  Quebec,  and  as  it  is  the  best  known 
occurrence  it  may  be  properly  referred  to  here. 

The  geologic  relations  (Fig.  100)  of  the  serpentines  and  associ- 
ated rocks  are  imperfectly  known,  but  it  appears  certain  that  they 


PLATE  XXXI.  —  General  view  of  asbestos  quarry,  Thetford  Mines,  Que. 
(H.  Ries,  Photo.) 

(303)  ' 


304 


ECONOMIC  GEOLOGY 


represent  a  series  of  stocks  and  sills,  cutting  rocks  of  Cambrian, 
Ordovician  and  Silurian  age.  The  rocks  of  the  asbestos  belt  are 
peridotite,  generally  much  altered  to  serpentine;  pyroxenite, 
frequently  altered  to  talc;  gabbro;  diabase;  and  a  breccia,  in 
part  of  volcanic  material. 

The  serpentine  is  an  alteration  product  of  peridotite,  it  and  the 
pyroxenite  being  of  laccolithic  character,  while  the  granite,  which 


c  a  o  a  c 

FIG.  101.  —  Photomicrograph  showing  vein  of  asbestos  (a),  with  irregular  margins, 
and  mid  streak  of  magnetite  (6).  Serpentinized  rock  (c)  on  either  side. 
(After  Dresser,  Can.  Geol.  Sun.,  Mem.  22.) 

forms  dikes  and  isolated  masses,  may  be  a  final  and  extremely  acid 
product  of  differentiation  of  the  general  magma  of  which  the  basic 
equivalent  is  the  olivine-rich  portion  of  the  peridotite. 

The  asbestos  is  found  forming  veins  in  the  serpentine,  the  width 
of  these  varying  from  a  mere  line  to  two  or  three  inches.  It  devel- 
oped probably  first  in  joint  planes,  and  afterwards  in  other  cracks, 
forming  thus  a  network  (Fig.  102).  An  interesting  and  suggestive 
feature  is  the  band  of  pure  serpentine  on  either  side  of  the  vein 
(Fig.  102),  the  ratio  of  the  asbestos  vein  to  the  entire  band  of  ser- 
pentine and  asbestos  being  1 : 6.6.  The  veins  are  formed  by  the 


- 


o 


a 

tJO 

I 
ffl 


(305) 


306 


ECONOMIC   GEOLOGY 


growth  of  minute  crystals  of  chrysotile,  perpendicular  to  the  walls, 
and  there  is  in  most  cases  a  central  parting  marked  by  a  film  of 
chromite  or  magnetite.  The  principal  mines  are  near  Thetford 
Mines  (PL  XXXI),  Black  Lake,  East  Broughton,  and  Danville. 
The  first-named  locality  is  of  great  importance. 


Peridotite  \       |  Asbestos  MM 

Serpentine^  Scale:    ™o  S? wide  " 

FIG.  102. — Diagram  showing  asbestos  and  serpentine  in  peridotite.    (After  Dresser, 

Econ.  Geol,  IV.} 

The  asbestos  milling  rock  forms  from  30  to  60  per  cent  of  the 
quantity  quarried,  and  6  to  10  per  cent  of  this  is  fiber. 

There  has  been  some  difficulty  in  explaining  satisfactorily  the 
origin  of  the  chrysotile  veins  in  serpentine,  for  we  have  here  two 
quite  different  forms  of  the  same  mineral.  Pratt,  in  attempting 
to  explain  the  origin  of  the  vein  filling,  believes  that  the  fissures 
represent  contraction  cracks  formed  around  the  edge  of  the  peri- 
dotite mass  while  cooling,  and  which  were  then  filled  by  aqueous 
solutions  from  which  the  chrysotile  crystallized.  Merrill,  on  the 
other  hand,  believes  the  fissures  to  have  been  caused  by  shrinkage 
incident  to  a  partial  dehydration  of  the  rocks  and  subsequent  filling 
by  crystallization  extending  from  the  walls  inward  (11,  5).  As 
suggested  by  Kemp,  a  loss  of  silica  may  also  have  produced  some 
shrinkage. 

Cirkel  (1),  believes  the  vein  crevices  to  have  been  formed  by 


MINOR  MINERALS  307 

partial  dehydration,  and  in  part  by  fracturing  resulting  from  the 
intrusion  of  the  granite. 

All  investigators  agree  on  the  wall  rock  being  the  source  of  the 
chrysotile.  Dresser  (3),  while  admitting  the  filling  of  the  veins  by 
infiltration,  suggests  that  they  have  been  enlarged  by  replacement 
of  the  walls  (Fig.  101).  He  points  out  that  the  veins  usually 
show  a  middle  parting  of  ore  minerals,  and  furthermore,  that 
microscopic  study  indicates  that  the  fibers  have  grown  outward 
from  each  side  of  the  seam  of  ore,  indicating  alteration  and  re- 
crystallization  of  the  serpentine  to  4  chrysotile  in  situ.  It  is 
furthermore  thought  that  the  depth  at  which  the  chrysotile 
formed  probably  precluded  the  existence  of  open  fissures  in  which 
the  material  could  have  crystallized. 

It  is  still  to  be  regarded  as  doubtful  whether  meteoric  or  mag- 
matic  water  was  operative  in  bringing  about  the  change,  although 
most  geologists  favor  the  latter. 

Other  Foreign  Deposits.  —  Outside  of  Canada,  Russia  is  the  only  other 
important  producer.  The  chief  deposits  are  in  the  Urals  (1)  near  the  station 
of  Baskenovo,  and  the  asbestos  occurs  as  cross  fiber  in  serpentine.  Other 
deposits  occur  in  the  Orenburg  district.  The  Russian  production  "for  1913 
was  18,594  short  tons.  Asbestos  of  the  hornblende  variety  is  obtained  in 
Italy,  but  the  production  is  small.  Crocidolite  has  been  mined  in  West 
Griqualand,  Africa,  but  the  industry  has  not  been  established  on  a  per- 
manent basis. 

Uses  of  Asbestos.  —  The  usefulness  of  asbestos  depends 
mainly  on  the  flexibility  of  its  fibers,  and  fibrous  structure,  and  to 
a  less  extent  on  its  low  conduction  of  heat  and  electricity,  and  on 
its  moderate  refractoriness.  Asbestos  is  used  in  fire-proof  paints, 
boiler  coverings,  for  packing  in  fire-proof  safes,  and  for  electric  in- 
sulation where  some  heat  resistance  is  necessary.  Chrysotile  is 
also  used  in  making  fire-proof  rope,  felt,  tubes,  cloth,  boards, 
blocks,  etc.  Asbestic  is  a  name  given  to  short-fibered  chrysotile 
mixed  with  serpentine.  Asbestine  is  a  pigment  of  which  asbestos  is 
an  important  ingredient,  and  serves  to  hold  up  other  heavier  pig- 
ments. Asbestos  is  also  used  for  filtering  in  chemical  work,  and 
for  this  purpose  the  amphibole  asbestos  is  better  adapted.  Many 
patented  mixtures  of  asbestos  and  other  materials,  such  as  Port- 
land cement,  etc.,  are  now  used  for  making  such  products  as  asbes- 
tos wood,  asbestos  slate,  asbestolith,  etc.  Asbestos  roofing  tile, 
roofing  felt  and  shingles  are  now  also  made  in  large  quantities. 


308 


ECONOMIC  GEOLOGY 


Production  of  Asbestos.  —  The  United  States  is  the  largest 
producer  of  manufactured  asbestos  products,  but  less  than  one 
per  cent  of  the  raw  material  is  mined  in  this  country.  Canada  is 
the  main  source  of  supply,  and  will  no  doubt  continue  so  for  a  long 
time.  Next  to  Canada,  Russia  is  the  largest  producer,  and 
exports  much  of  its  product  to  the  United  States. 

The  production  and  imports  from  1910  to  1914  were  as  follows: — 

ANNUAL  PRODUCTION  AND  ANNUAL  VALUE  OF  IMPORTS  OF  ASBESTOS  INTO 
THE  UNITED  STATES,  1910-1914 


YEAR 

PRODUCTION 

VALUE  OF  IMPORTS 

SHORT  TONS 

VALUE 

UNMANU- 
FACTURED 

MANU- 
FACTURED 

TOTAL 

1910    .     .     . 
1911     .     .     . 
1912     .     .     . 
1913     .     .     . 
1914     .     .     . 

3693 
7604 
4403 
1100 
1247 

$   68.357 
119,935 
87,959 
11,000 
16,810 

$1,235,170 
1,413,541 
1.456,012 
1,928,705 
1,407,754 

$308,078 
290,098 
363,759 
378,961 
371,469 

$1,543,248 
1,703,639 
1.819,771 
2,307,666 
1,779,223 

VALUE  OF  CANADIAN  PRODUCTION,  EXPORTS  AND  IMPORTS,  1912-1914 


YEAR 

PRODUCTION 

EXPORTS 

IMPORTS 

1912 

$3,117,572 

$2,349,353 

$461,449 

1913 

3  830  909 

2,848,047 

520,082 

1914                    .... 

2,892,266 

2,298,646 

RANGE  OF  NEW  YORK   PRICES  PER   SHORT  TON 
SOTILE  FIBER,   1912-1914 


FOR  CANADIAN    CHRY- 


1912 

1913 

1914 

No.  1  crude       
No   2  crude 

$300-$325 
175-  200 

$320-$350 
200-  225 

$350-$375 
225-  250 

No    2  fiber               .... 



75-  100 

75-   100 

Shorter  fibers    .     .     .     .     . 



10-     30 

10-     30 

REFERENCES    ON    ASBESTOS 

1  Cirkel,  Can.  Dept.  Inter.,  Mines  Branch,  No.  69,  1910.  (Canada  occur- 
rence and  uses.)  2.  Diller,  U.  S.  Geol.  Surv.,  Bull.  470,  1911.  (U.  S.) 
3.  Dresser,  Econ.  Geol.,  IV:  130,  1909.  (Quebec.)  4.  Hopkins,  Ga. 
Geol.  Surv.,  Bull.  29,  1914.  (Ga.)  5.  Miller  and  Knight,  Ont.  Bur. 
Mines,  XXII,  Pt.  2:  117,  1913.  (Ont.  actinolite.)  6.  Jones,  Asbestos 
and  Asbestic:  Their  Properties,  Occurrences,  and  Use  (London),  1897. 
7.  Kemp,  U.  S.  Geol.  Surv.,  Min.  Res.,  1900:  862,  1901.  (Vt.)  8. 
Marsters,  Kept.  State  Geologist  Vermont,  1903-1904:  86,  1904.  (Ver- 


MINOR  MINERALS  309 

mont.)  9.  Marsters,  Geol.  Soc.  Amer.,  Bull.  XVI:  419,  1905.  10. 
Merrill,  Non-metallic  Minerals:  183,  1910.  (General.)  11.  Merrill, 
Geol.  Soc.  Amer.,  Bull.  XVI:  416,  1905.  (Origin.)  12.  Pratt,  Min- 
eral Census,  1902,  Report  on  Mines  and  Quarries:  973,  1904.  13. 
Merrill,  Proc.,  U.  S.  Nat.  Mus.,  XVIII:  281.  (Asbestos  and  asbesti- 
form  minerals.)  14.  Pratt,  M in.  World,  July  8,  1905.  (Ariz.)  15.  Rich- 
ardson, Vt.  State  Geologist,  Rept.,  1909-10;  315,  1910;  Ibid.,  1911-12: 
269,  1910.  (Vt.)  16.  Watson,  Min.  Res.  Va.:  285,  1907. 


BARITE 

Properties  and  Occurrence.  - —  Barite,  the  sulphate  of  barium, 
contains  when  pure,  BaO  65.7  per  cent,  and  SOs  34.3  per  cent. 
Its  specific  gravity  is  4.3  to  4.6  and  its  hardness  2.5  to  3.5.  It. 
is  commonly  white,  opaque  to  translucent,  and  crystalline, 
while  the  texture  is  granular,  fibrous,  or  more  rarely  earthy. 
Barite  is  a  common  mineral  which  may  be  found  in  many  kinds  of 
rocks — igneous,  sedimentary,  and  metamorphic.  It  has  in  nearly 
all  cases  been  formed  by  deposition  from  aqueous  solutions,  and 
is  not  found  as  an  original  constituent  of  igneous  rocks,  nor  in 
contact  metamorphic  zones,  or  pegmatite  veins.  Furthermore 
it  is  not  a  product  of  dynamo-metamorphism. 

Analyses  of  many  rocks  show  at  least  small  amounts  of  barium, 
and  it  has  also  been  noted  in  orthoclase  feldspars  and  some 
micas. 

It  has  frequently  been  found  in  spring  and  mine  waters,  where 
it  may  be  in  solution  as  the  chloride,  carbonate,  or  perhaps  even 
as  sulphate.1  Contact  of  solutions  containing  the  first  two  with 
sulphate  waters  will  form  barium  sulphate,  although  its  precipita- 
tion may  be  retarded  by  the  presence  of  chlorides.  Travertine 
deposits  containing  varying  amounts  of  barite  are  also  known, 
one  described  from  Doughty  Springs,  Colo.,  showing  from  a 
small  percentage  up  to  95  per  cent 2  barium  sulphate. 

These  facts  indicate  that  barite  is  deposited  from  solution, 
and  probably  most  deposits  are  formed  in  this  manner. 

Form  of  Deposits.  —  Commercially  important  deposits  of 
barite  may  include  the  vollowing  types: 

I.  Veins  formed  by  the  filling  of  fissures,  by  replacement,  or 
by  cementing  of  fault  breccias,  the  wall  rocks  being  lime- 

1  Barium  sulphate  has  a  solubility  of  1  part  in  400,000  of  water,  but  the  natural 
compound  is  said  to  be  six  times  more  soluble  than  the  artificial. 

2  Headden,  Col.  Sci.  Soc.,  Proc.,  VIII:    1,  1905. 


310  ECONOMIC  GEOLOGY 

stone,    quart  zite,    sandstone,    schist,    gneiss   or   volcanic 
rocks  in  the  different  occurrences  (3,  5a,  8a,  11). 
II.  Bedded    deposits    (so   called),   formed   by   replacement   of 
pyrite  (la). 

III.  Irregular  masses,  occurring  as  replacements  of  limestone  (ll). 

IV.  Lumps  in  residual  clays  (ll). 

V.  Filling  the  interstices  of  brecciated  masses  (ll,  12). 

Associated  Minerals  (3,  5a,  ll).  —  These  vary  with  the  indi- 
vidual deposit.  The  vein  and  replacement  types  often  contain 
metallic  sulphides,  especially  galena,  but  sometimes  sphalerite, 
chalcopyrite,  and  pyrite.  Galena  is  harmful,  since  it  discolors  the 
ground  product,  and  other  sulphides  may  cause  similar  trouble. 
Quartz,  calcite,  and  fluorite  are  also  at  times  abundant,  the  last- 
named  being  especially  noted  in  Kentucky  and  Tennessee  veins 
as  well  as  in  some  of  the  Great  Valley  occurrences  of  Virginia. 

Residual  deposits  especially  may  carry  considerable  iron  and 
manganese  oxides,  as  well  as  quartz.  Small  amounts  of  iron 
oxide  can  be  removed  by  treating  the  ground  product  with  H2S04, 
but  the  manganese  is  more  difficult  to  eliminate  (ll). 

Barite  veins  have  not  been  sufficiently  worked  in  the  United 
States  to  determine  whether  there  is  much  change  with  depth, 
but  this  has  been  noted  in  several  European  ones  (la). 

Geologic  Age  of  Associated  Rocks.  —  This,  in  the  case  of 
the  deposits  of  the  United  States  and  Canada,  may  be  briefly 
summarized  as  follows: — 

Triassic.     Virginia. 

Mississippian.     Western  Kentucky. 

Devonian.     Five  Islands,  N.  S. 

Ordovician.     Missouri. 

Cambro-Ordovician.  Central  Kentucky,  Tennessee,  Appa- 
lachian Valley  region  of  Virginia,  Georgia,  Alabama,  Maryland, 
and  Pennsylvania. 

Of  these  the  deposits  of  the  Cambro-Ordovician  are  the  most 
important,  practically  all  the  United  States  production  coming 
from  Missouri  and  the  Appalachian  states. 

Distribution  of  Barite  in  the  United  States.  —  The  location 
of  the  deposits  in  the  eastern  half  of  the  country  is  shown  on  the 
map,  Fig.  103,  and  the  more  important  ones  at  least  may  be  briefly 
referred  to  since  they  represent  several  different  types  of  occurrence. 

Missouri  (3). — Barite  forms  scattered  deposits  in  Washington 
and  adjacent  counties,  though  many  of  the  occurrences  are  clus- 


MINOR  MINERALS 


311 


FIG.  103.  —  Map  of  barite  deposits  of  Appalachian  states.     (After  Watson  and 
Grasty,  Amer.  Inst.  Min.  Engrs.,  Bull  98,  1915.) 


FIG.  104. Barite  veins  in  Potosi  dolomite,  southeastern  Missouri.     (After  Buck- 
ley, Mo.  Bur.  Geol.  and  Mines,  IX.) 


312 


ECONOMIC   GEOLOGY 


tered  around  Mineral  Point,  Washington  County.  The  material 
is  obtained  from  the  Potosi  (Ordovician)  limestones,  in  which  it 
occurs  as  replacement  veins  (Fig.  104)  mixed  with  lead,  or  in 
residual  clay  with  chert  and  drusy  quartz,  the  whole  forming  a 
sheet-like  deposit,  at  no  great  depth  (Fig.  105). 


OH  WM        EE3 

Clay     Drusy  Quartz      Chert          Dolomite 


.Barita 


FIG.    105.  —  Barite   deposit   in   residual   clay   near  Mineral    Point,  Mo. 
(After  Riicl-lrv.  Mr-    Pur.  (lenl.  nnd  Mines,  IX.) 

Virginia  (11). — Barite  occurs  in  many  parts  of  the  state  (Fig. 
106),  but  the  industry  has  been  confined  mainly  to  a  few  localities. 
The  barite  deposits  may  be  grouped  into  three  areas,  as  follows: 
1.  Deposits  of  the  Triassic  red  shale-sandstone  series,  in  which  the 
barite  is  associated  with  red  shales  and  impure  limestones.  It  has 
been  deposited  from  solution  in  fractures  in  the  red  shales,  or 


FIG.  106. —  Map  of  Virginia  showing  location  of  worked  areas  of  barite. 
(After  Watson,  Min.  Res.  Va.,  1907.) 


MINOR  MINERALS 


313 


more  rarely  as  thin,  tabular  replacement  masses  in  the  limestone. 
2.  Deposits  of  the  crystalline  metamorphic  area,  probably  for  the 
most  part  of  pre-Cambrian  age,  and  in  which  the  barite  occurs  either 
as  irregular  lenses 
of  100-200  feet  di- 
ameter in  lime- 
stone, or  as  nodules 
in  a  residual  lime- 
stone-schist clay 
(Fig.  107).  In  one 
locality  the  barite 
fills  a  vein  in  sili- 
ceous schists,  re- 
mote from  calcare- 
ous rocks.  3.  The 
mountain  region  of 


southwestern 
ginia.     Here 


FIG.  107.  —  Ideal  section  in  Bennett  Barite  Mine,  Pitt- 
sylvania  County,  Va.  (After  Watson,  Min.  Res. 
Va.,  1907.) 


Vir- 

the 

barite,    which    is 
associated  with  the  Shenandoah  limestone  (Cambro-Ordovician), 
is  found  either  as  lumps  in  the  residual  clay,  or  in  the  fresh  rock. 

The  frequent  association  of  the  barite  with  limestone  in  all  the 
areas  is  quite  noticeable. 

The  second  region  is  the  most  important  producer. 

Watson  believes  that  the  source  of  the  barite  is  the  rocks  in 
which  the  deposits  are  now  found.  Thus  in  the  Valley  region  it 
was  no  doubt  derived  from  the  Shenandoah  limestone,  while  in 
the  Piedmont  area  it  may  have  come  either  from  the  crystalline 
schists  or  limestone  mass.  That  of  the  Thaxton  area  was  doubt- 
less obtained  from  the  silicates  of  the  granite.  The  liberation  and 
removal  of  the  barium  in  solution  is  considered  to  have  been  ac- 
complished by  shallow  circulations.  The  barite  is  always  crystal- 
line in  texture. 

Kentucky  (5a,  8,  ll).  — The  vein  type  of  occurrence  is  well 
developed  in  this  state,  there  being  two  areas.  Those  veins 
in  the  central  part  of  the  state  (Figs.  108,  109)  are  confined  to 
the  Ordovician,  and  are  found  filling  simple  fissures,  or  fault  frac- 
tures, the  chief  associates  being  calcite,  fluorite,  sphalerite  and 
galena.  They  are  from  1  to  3  feet  in  width,  with  a  maximum  of 
24  feet,  and  have  been  mined  to  depths  of  100  to  325  feet.  In  the 
western  area,  fluorspar  is  the  chief  mineral,  with  barite  of  second- 


314 


ECONOMIC  GEOLOGY 


o^W    V\\M^        V\\     U 


FIG.  108.  —  Map  of  barite  veins  near  Lexington,  Ky.     (After  Fohs,  Ky.  Geol  Surv. 
4th  ser.,  I:  441,  1913.) 


Ko.3 

Ho.*j§§nj 

':iTf?fi:rjttZKni 


No.5 
No.6_ 


East 


.  . 

ytes      Fluorspar        Calcite       I.imestonB 


FIG.  109.  —  Sections  of  a  Kentucky  barite  vein.     (After  Fohs.) 


MINOR  MINERALS 


315 


ary    importance,    and    the     veins     occurring    in    Mississippian 
limestone. 


Georgia  (6). —  Barite  deposits  are  known  to  occur  near  Cartersville, 
Ga.,  associated  with  the  Beaver  (Cambrian)  limestone  and  Weisner  (Cam- 
brian) quartzite  (Fig.  110). 
It  is  thought  that  the  bar- 
ite was  originally  deposited 
by  the  replacement  of  cer-  N;-\v.\::>^;^  Limonite 
tain  beds  of  the  shaly  lime- 
stone overlying  the  quartz- 
ite, but  it  now  forms  nodules 
and  masses  sea  ttered  through 
a  residual  clay,  and  mixed 
with  some  quartzite  frag- 
ments. Gravity  has  prob- 
ably aided  in  concentrating 
the  barite  into  workable 
deposits. 

Other  Occurrences.  — 
The  barite  of  Gaston 
County,  North  Carolina, 

occurs  as  lenticular  fissure  fillings  in  schist,  associated  with  quartz,  galena, 
sphalerite,  and  pyromorphite,  while  that  of  South  Carolina  is  in  similar 
rocks;  that  in  Tennessee  is  either  in  residual  clay  overlying  the  Knox  dolo- 
mite (Cambro-Ordovician)  as  in  the  Sweet  water  district,  or  as  veins  in 
schist,  as  in  the  French  Broad  district  (7,  11). 


Quartzite 

Shaly  limestone 

FIG.  110. —  Sketch  section  showing  relations  of 
barite  and  limonite  to  underlying  formations 
near  Cartersville,  Ga.  (After  Hayes  and 
Phalen,  U.  S.  Geol.  Surv.,  Butt.  340.) 


ANALYSES  OF  BARITE 


I 

II 

III 

IV 

V 

VI 

VII 

BaO  .... 

64.72 

54.95 

98.541 

94.201 

98.821 

93.591 

97.  561 

Fe2O3.     .     .     . 

.06 

.06 



.11 

.33 

.32 

.42 

Si02  .... 

.25 

.55 

.95 

.05 

.27 

4.76 

.41 

CaO  .... 

tr. 

.20 

.02 

4.442 







SrO    .     .     .     . 

tr. 

6.75 











S03    .     .     .     . 

33.82 

34.22 











ZnO  .... 



1.23 











MgO      .     .     » 





22 









F  .     .     . 



.14 











BaSO4 


2  CaC03 


I.  Mexico,  Ky.;  II.  Danville,  Ky.;  III.  Five  Islands,  N.  S.;  IV.  Lake 
Ainslee,  Cape  Breton;  V.  Eton,  Murray  Co.,  Ga.;  VI.  Cherokee 
Co.,  S.  Ca.;  VI.  Sweetwater  district,  Tennessee.  All  from  Reference  11. 


316  ECONOMIC   GEOLOGY 

Canada  (8a,  12).  —  The  only  productive  district  is  at  Lake 
Ainslie,  Cape  Breton,  where  barite  is  found  in  veins  in  the  pre- 
Cambrian  felsite.  Calcite  and  fluorite  are  occasional  associates. 
Other  veins  are  found  in  schists  of  the  Louisburg  shale  formation 
at  North  Cheticamp. 

Near  Five  Islands,  Nova  Scotia,  barite  has  been  found  filling 
fissures  and  brecciated  zones  in  Devonian  slate  and  quart zite, 
but  the  deposits  have  not  been  worked  steadily.  The  barite  here 
is  believed  to  have  been  deposited  by  vadose  waters,  as  small 
amounts  of  it  are  shown  to  occur  in  the  surrounding  rocks. 

Other  Foreign  Deposits.1  —  Barite  deposits  are  widely  distributed,  but 
those  of  Germany  (la)  are  probably  the  most  important.  They  include: 
1.  A  curious  bituminous  barite  deposit,  near  Meggen,  Westphalia,  supposed 
to  have  originated  by  the  replacement  of  portions  of  a  bedded  Devonian 
pyrite  which  in  turn  grades  into  limestone.  2.  Vein  deposits  closely  asso- 
ciated often  with  the  Permian,  and  showing  a  considerable  variety  of  metallic 
minerals.  The  barite  is  of  higher  grade  than  the  Meggen  product.  Among 
other  European  deposits  may  be  mentioned  the  replacement  ones  in  Car- 
boniferous limestone  of  Belgium,  as  well  as  minor  vein  deposits  of  France, 
Italy,  Austria,  and  Great  Britain. 

Origin  of  Barite.  —  Sulphate  of  barium  is  but  slightly  soluble, 
but  is  perceptibly  decomposed  by  a  dilute  solution  of  carbonated 
alkali.  If  present  in  one  of  the  silicates  (feldspar)  in  granite  it 
might  be  decomposed  by  sulphates  of  the  alkalies,  lime  sulphate, 
or  magnesium  sulphate,  resulting  in  precipitation  of  barium 
sulphate. 

Buckley  (3)  believes  tjial;  the  Missouri  barite  was  possibly  de- 
rived from  solutions  of  the  bicarbonate,  precipitated  with  alkaline 
sulphates. 

Watson  (ll)  suggested  that  in  the  case  of  the  Virginia  barite  it 
was  probably  taken  into  solution  as  the  soluble  bicarbonate,  and 
precipitated  under  favorable  conditions  as  the  insoluble  sulphate. 
Laboratory  experiments  by  Dickson  (4)  with  solutions  of  barium 
carbonate  on  selenite  crystals  and  pure  anhydrite  in  presence  of 
C02,  and  on  pyrite  crystals  in  presence  of  an  oxidizing  agent, 
water,  caused  precipitation  of  barium  sulphate  in  each  case. 

Mining,  Preparation,  and  Uses  (9a,  ll).  —  Barite  deposits 
may  be  worked  by  open  cuts,  shafts  or  pits.  The  greatest  depth 
reached  in  mining  is  probably  not  over  200  feet. 

The  removal  of  impurities  from  merchantable  barite  includes 

1  Dammer  und  Tietze,  Nutzbaren  Mineralien,  II:   7,  1914. 


MINOR  MINERALS 


317 


hand  cobbing,  sorting  or  grading,  washing  and  crushing.  Ground 
barite  requires  bleaching  with  sulphuric  acid  to  remove  iron,  dry- 
ing and  grinding. 

Since  the  barite  deposits  are  usually  small  and  pockety,  the  mill 
must  be  located  to  permit  its  drawing  on  numerous  and  changing 
sources  of  supply. 

Washed  barite  is  used  in  the  manufacture  of  paper,  for  coating 
canvas  ham  sacks,  in  pottery  glazes,  and  in  the  manufacture  of 
barium  hydroxide.  Its  main  use  perhaps  is  in  white  pigments  to 
mix  with  white  lead,  zinc  white,  or  a  combination  of  both  of  these 
pigments..  Although  formerly  regarded  as  an  adulterant  of 
white  pigments,  it  is  now  considered  to  make  the  mixture  more 
permanent,  less  likely  to  be  attacked  by  acids,  and  freer  from 
discoloration.  Lithophone  paint  is  a  mixture  of  barium  sulphate 
(68  per  cent),  zinc  oxide  (7.28  per  cent),  and  zinc  sulphide  (24.85 
per  cent). 

Barium  hydrate  is  used  chiefly  in  the  beet-sugar  industry; 
barium  chloride  in  the  color  industry  and  the  manufacture  of 
wall  paper;  barium  carbonate  as  a  chemical  reagent,  in  glass 
manufacture,  and  to  prevent  scumming  of  clay  products.  Other 
uses  are  in  the  manufacture  of  rubber,  asbestos,  tanning  leather, 
enameling  iron  and  oilcloth,  poker  chips,  boiler  compounds, 
insecticides,  hydrogen  peroxide,  etc. 

Production  of  Barite.  —  The  production  of  barite  for  several 
years  is  given  below. 

PRODUCTION  OF  CRUDE  BARITE  IN  THE  UNITED  STATES,  1912-1914, 

BY  STATES 


STATE 

1912 

1913 

1914 

SHORT 
TONS 

VALUE 

AVER- 
AGE 
PRICE 

PER 

TON 

SHORT 
TONS 

VALUE 

AVER- 
AGE 
PRICE 

PER 

TON 

SHORT 
TONS 

VALUE 

AVER- 
AGE 
PRICE 

PER 

TON 

Missouri  . 
Tennessee  1 
Kentucky   / 
Other  states2 

Total     . 

24,530 
13,718 
9,230 

$117,035 
8,682 
27,596 

$4.77 
2.34 
2.99 

31,131 
!2,098 
12,069 

$117,638 
3,568 
35,069 

$3.78 
1.70 
2.91 

33,317 
8,932 
9,298 

$112,231 
14,393 
27,091 

$3.37 
1.61 
2.91 

37,478 

$153,313 

$4.09 

45,298 

$156,275 

$3.45 

51,547 

$153,715 

$2.98 

1  Tennessee  alone. 

2  Includes  1912:   Georgia,  North  Carolina,  and  Virginia;    1913:   Georgia,  North 
Carolina,   South  Carolina,   and   Virginia:     1914:    Alabama,   California,   Georgia, 
North  Carolina,  South  Carolina,  and  Virginia. 


318 


ECONOMIC  GEOLOGY 


Imports. — The  imports  of  barium  compounds  for  1912  to  1914 
were  as  follows: — 

VALUE  OF  THE  IMPORTS  OF  BARIUM  COMPOUNDS,  1912-1914 


1912 

1913 

1914 

Barium  carbonate 

Barium  binoxide 
Barium  chloride 
Blanc-fixe,  or  artifi 

Natural        .... 
Manufactured       .     ,- 

$  15,777 
9,938 
252,320 
27,655 
70,327 

$  13,116 
38,949 
239,000 
37,620 
62,785 

$     8,084 
36,305 
332,709 
68,866 
32,619 

cial  barium  sulphate  . 

$376,017 

$391,470 

$478,583 

PRODUCTION  OF  BARITE  IN  CANADA,  1912-1914 


YEAR 

QUANTITY,  SHORT  TONS 

VALUE 

1912.      .-.......* 

7654 

$32,410 

1913  
1914 

5987 
612 

41,774 
6  129 

REFERENCES    ON    BARITE 

1.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  616:  579,  1916.  la.  Bartling,  Schwer- 
spatlagerstatten  Deutschlands,  1911.  2.  Burchard,  Min.  and  Sci.  Pr., 
CIX:  371,  1914.  (Alas.)  3.  Buckley,  Mo.  Bur.  Geol.  and  Mines, 
IX,  Pt.  I:  238.  (Mo.)  4.  Dickson,  Sch.  of  M.  Quart.,  XXIII:  366. 
(Conc'n.  in  limestone.)  5.  Fay,  Eng.  and  Min.  Jour.,  LXXXVII: 
137,  1909.  (Tenn.)  5o.  Fobs,  Ky.  Geol.  Surv.,  4th  Ser.,  I:  441,  1913. 
(Ky.)  6.  Hayes  and  Phalen,  U.  S.  Geol.  Surv.,  Bull.  340:  458,  1908. 
(Ga.)  7.  Henegar,  Res.  Tenn.  II,  No.  11.  (Tenn.)  8.  Miller,  Ky., 
Geol.  Surv.,  Bull.  2:  24,  1905.  (Ky.)  8a.  Poole,  Can.  Geol.  Surv., 
No.  953,  1907.  (Nova  Scotia.)  9.  Pratt,  N.  Ca.  Geol.  Surv.,  Econ. 
Pap.  6:  62,  1902.  (N.  Ca.)  9a.  Steel,  Amer.  Inst.  Min.  Engrs., 
Trans.  XL:  711,  1910.  (Mo.)  10.  Stose,  U.  S.  Geol.  Surv.,  Bull. 
225:  515,  1904.  (Pa.)  11.  Watson  and  Grasty,  Amer.  Inst.  Min. 
Engrs.,  Bull.  98,  1915.  (Appalachian  states  and  general.)  12.  Warren, 
Econ.  Geol.  VI:  799,  1911.  (Five  Islands,  N.  S.) 


DIATOMACEOUS    EARTH    (KIESELGUHR) 

Properties  and  Occurrence  (i,  8).  — This  material  when  pure 
is  made  up  of  the  siliceous  tests  of  diatoms  (Fig.  Ill) .  Chemically 
it  is  a  variety  of  opal.  It  resembles  chalk  or  clay  in  appear- 
ance, but  is  very  much  lighter  than  either  of  these,  and  can 
also  be  distinguished  from  the  former  substance  by  the  fact 
that  it  does  not  effervesce  with  acid.  A  microscopic  examina- 


MINOR  MINERALS 


319 


tion  serves  to  identify  it  at  once.  Diatomaceous  earth  is  com- 
monly white  or  light  gray  in  color,  but  may  be  brownish,  dark 
gray,  or  even  black,  due  to  the  presence  of  organic  matter.  It  is 
exceedingly  porous.  If  pure,  it  should  show  little  else  than  silica 
and  water  on  analysis,  but  most  earths  have  at  least  small  amounts 


FIG.   111.  —  Diatomaceous  earth  from  Lompoc,  Calif.     (Calif.  State  Min.  Bur., 

Bull.  38.) 

of  other  substances,  and  some  contain  a  large  amount  of  clayey 
impurities  (see  analysis  VI  below). 

The  following  analyses  represent  the  composition  of  a  number 
of  American  earths :  — 

ANALYSES  OF  DIATOMACEOUS  EARTH 


I 

II 

in 

IV 

V 

VI 

VII 

VIII 

SiO2   .     .     . 

86.92 

72.50 

86.89 

80.53 

81.53 

63.17 

82.85 

86.515 

A12C>3      .     . 

4.27 

11.71 

2.32 

5.89 

3.43 

19.30 

6.76 

.449 

Fe2O3      .     . 

— 

2.35 

1.28 

1.03 

3.34 

6.32 

2.34 

.374 

CaO   .     .     . 

1.60 

.32 

.43 

.35 

2.61 

.06 

.35 

.120 

MgO  .     .     . 

tr. 

.83 

tr. 

— 

— 

.69 

1.06 

12.000 

Alkalies  .     . 

2.48 

1.88 

3.58 

— 

2.59 

3.14 

2.06 

— 

TiO2  .     .     . 

— 

— 

— 

— 

— 

.88 

1.09 

— 

Ign.  loss  . 

5.13 

9.54 

4.89 

12.03 

6.04 

6.39 

3.40 

— 

100.40 

99.13 

99.39 

99.83 

99.54 

99.95 

99.91 

98.458 

I.  Porcelain  diatomaceous  shale,  Point  Sal,  Santa  Barbara  Co., 
Calif.  II.  Soft  shale,  Orcutt,  Santa  Barbara  Co.,  Calif.  III.  Monterey, 
Santa  Barbara  Co.,  Calif.  IV.  Lake  Umbagog,  N.  H.  V.  Pope's  Creek, 
Md.  VI.  Wilmot,  Virginia ;  very  clayey.  VII.  Richmond,  Virginia. 
VIII.  Herkimer,  N.  Y. 


320  ECONOMIC   GEOLOGY 

Distribution  in  the  United  States.  —  Diatomaceous  earth  occurs 
as  deposits  of  comparatively  small  extent  in  the  bottoms  of  ponds, 
lakes,  and  swamps,  sometimes  mixed  with  organic  matter,  or  it  may 
form  bedded  deposits  of  marine  origin  and  showing  at  times  great 
extent  as  well  as  thickness.  A  few  localities  may  be  mentioned. 

California  (1,  2,  4).  —  Important  deposits  of  diatomaceous  earth 
are  known  to  occur  at  a  number  of  points  in  the  Coast  Ranges  of 
California,  but  the  most  important,  perhaps,  are  those  found  in 
northern  Santa  Barbara  County.  There  it  occurs  mainly  in  the 
Monterey  (Middle  Miocene)  and  in  the  lower  part  of  the  Fernando 
(Upper  Miocene)  formations. 

The  deposits  range  from  those  of  high  purity,  through  impure 
shaly  beds,  to  flinty  deposits.  The  earth  is  found  interbedded 
With  volcanic  ash  at  some  localities  (south  of  Lompoc),  and  with 
limestones  at  others.  The  thickness  of  the  diatom  deposits  is  often 
remarkable,  being  2400  feet  south  of  Harris,  and  4700  feet  between 
the  Santa  Ynez  and  Los  Alamos  valleys. 

New  York  (3,  5) .  —  Although  diatomaceous  earth  is  known  to  occur 
at  several  localities,  the  only  one  recently  worked  is  near  Hinckley,  Her- 
kimer  County,  where  it  forms  a  bed  2  to  30  feet  in  White  Head  Lake.  It 
is  purified  by  washing  and  pressed  -into  cakes. 

Virginia  (8) .  —  In  the  Atlantic  Coastal  Plain,  deposits  of  diatomaceous 
earth  are  not  uncommon  in  the  Miocene  (Tertiary)  formations,  and  those 
around  Richmond  have  long  been  known.  Along  the  Rappahannock 
River,  especially  below  Wilmot,  there  are  long  exposures,  the  bluffs  of  the 
material  standing  out  prominently  in  the  sunlight. 

Maryland.  —  Beds  of  diatomaceous  earth  occur  at  the  base  of  the  Calvert 
(Tertiary)  formation,  deposits  being  known  in  Anne  Arundel,  Calvert, 
and  Charles  counties.  Few  of  them  are  worked,  although  some  attain  a 
thickness  of  at  least  25  or  30  feet. 

Other  States.  —  Connecticut,  Massachusetts,  Florida,  Nevada,  and  Wash- 
ington are  also  producers,  but  the  deposits  are  of  limited  extent. 

Foreign  Deposits.  —  Diatomaceous  earth  is  known  to  occur  at  a  number 
of  Canadian  localities,  but  the  only  production  recorded  is  from  Nova  Scotia. 
Many  deposits  are  known  in  Europe.1 

Uses.  —  Diatomaceous  earth,  on  account  of  its  porous  character, 
was  formerly  used  as  an  absorbent  of  nitroglycerine  in  dynamite, 
but  little  or  none  appears  to  be  now  employed  for  this  purpose  in 
the  United  States.  It  can  be  used  for  polishing  powders,  and  as  a 
nonconductor  of  heat  it  has  been  occasionally  utilized  for  steam 
boiler  backing,  for  wrapping  steam  pipes,  and  for  fireproof  cement. 

1  Dammer  and  Tietze,  Nutzbaren  Mineralien,  I:   202,  1913. 


MINOR  MINERALS  321 

Mixed  with  clay,  or  even  alone,  it  can  be  used  for  making  porous 
partition  brick  or  tile.  Some  of  the  California  material  can  be  cut 
into  any  desired  shape,  and  used  as  a  filter  stone,  or  even  for  build- 
ing purposes.  Recently  it  has  been  used  in  talking  machine 
records. 

In  Europe,  especially  in  Germany,  it  has  of  late  years  found 
extended  application.  It  has  been  used  in  the  preparation  of  arti- 
ficial fertilizers,  especially  in  the  absorption  of  liquid  manures,  in  the 
manufacture  of  water  glass,  of  various  cements,  of  glazing  for  tiles, 
of  artificial  stone,  of  ultramarine  and  various  pigments,  of  aniline 
and  alizarine  colors,  of  paper,  sealing  wax,  fireworks,  gutta-percha 
objects,  Swedish  matches,  solidified  bromine,  scouring  powders, 
papier-mache,  and  a  variety  of  other  articles.  There  is  said  to  be  a 
large  and  steadily  growing  demand  for  it. 

The  production  is  given  under  Abrasives,  where  it  is  included 
with  Tripoli. 

REFERENCES  ON  DIATOMACEOUS   EARTH 

1.  Arnold  and  Anderson,  U.  S.  Geol.  Surv.,  Bull.  315  : 438,  1907.  (Cali- 
fornia.) 2.  Aubury,  Calif.  State,  Min.  Bur.,  Bull.  38.  3.  Cox,  Trans. 
N.  Y.  Acad.  Sci.,  XIII :  98,  1893.  (New  York.)  4.  Fairbanks, 
U.  S.  Geol.  Atlas  Folio,  101:  14,  1904.  (California.)  5.  Newland 
N.  Y.  State  Mus.,  Bull.  102:  67,  1906.  (New  York.)  6.  Pardee  and 
Hewett,  Min.  Res.  Oregon,  I:  71,  1914.  (Ore.)  7.  Phalen,  U.  S. 
Geol.  Surv.,  Min.  Res.,  1908.  8.  Ries,  Va.  Geol.  Surv.,  Bull.  II:  143, 
1906  (Virginia.) 

FELDSPAR 

• 

Properties  and  Occurrence.  —  The  feldspar  group  includes 
several  species,  all  silicates  of  alumina,  with  one  or  more  of  the 
bases — potash,  soda,  and  lime.  These  species  may  be  divided  into 
two  groups,  viz.,  the  potash  feldspars,  and  the  lime-soda  feld- 
spars, a  division  which  is  not  without  practical  value,  since  the  two 
groups  differ  somewhat  in  their  fusibility  and  mineral  associates. 

Orthoclase  and  microcline,  whose  composition  is  expressed  by 
the  formula  KAlSiaOg,  are  the  chief  representatives  of  the  first 
group.  Expressed  in  percentages  their  composition  is  SiC>2,  64.7 
per  cent;  A12O3,  18.4  per  cent;  K2O,  16.9  per  cent.  Soda  may 
partly  or  wholly  replace  the  potash.  If  the  latter  occurs,  anortho- 
clase  results.  Potash-soda  feldspars  are  usually  pinkish  to  nearly 
white,  but  some,  as  that  mined  in  Ontario,  is  a  distinct  reddish 
color.  Nevertheless,  even  the  strongly  colored  ones  may  calcine 


322  ECONOMIC   GEOLOGY 

to  a  pure  white  color,  and  show  a  sufficiently  low  iron  oxide 
content  to  permit  their  use  in  pottery  manufacture. 

The  lime-soda  feldspars,  or  plagioclases,  present  a  series  of  com- 
pounds ranging  from  the  soda  feldspar,  albite,  through  soda-lime 
feldspars,  to  the  pure  lime  spar,  anorthite,  at  the  other  end. 

Albite,  whose  formula  is  NaAlSi3O8,  has  SiC>2,  68.7  per  cent; 
A1203,  19.5  per  cent;  Na2O,  11.8  per  cent.  Anorthite,  CaALSioOg, 
has  Si02,  43.2  per  cent;  A12O3,  36.7  per  cent;  CaO,  20.1  per  cent. 

All  feldspars  in  melting  pass  gradually  from  a  solid  condition  to 
that  of  a  very  stiff  fluid  (5),  complete  fusion  occurring  usually 
about  Seger  cone  9(1310°C.).  A  mixture  of  soda  and  potash  spar 
seems  to  have  a  slightly  lower  fusing  point,  while  the  lime  spar, 
anorthite,  does  not  melt  until  1532°  C.  (5). 

Most  of  the  feldspar  quarried  in  the  United  States  is  the  potash- 
soda  type,  but  in  some  localities  the  soda  spar,  albite,  may  be  present. 
If  plagioclase  is  present  in  feldspar  used  for  pottery,  it  is  generally 
albite. 

Feldspars  are  widely  distributed  in  many  igneous  and  metamor- 
phic  rocks,  but  in  most  cases  they  are  so  intimately  mixed  with 
other  minerals,  that  their  extraction  is  not  commercially  practi- 
cable, and  it  is  only  when  found  in  pegmatites  that  they  are  worked. 
Of  these  rocks,  two  types  are  recognizable,  viz.  the  granite  peg- 
matites, which  are  very  coarse-grained  and  carry  quartz,  potash 
feldspar,  muscovite,  biotite,  tourmaline,  etc.,  and  the  soda  pegma- 
tites, which  consist  mainly  of  albite  with  a  little  hornblende.  Most 
of  the  deposits  worked  in  the  United  States  belong  to  the  first  type, 
only  a, few  from  southeastern  Pennsylvania  and  northeastern  Mary- 
land falling  in  the  second  class. 

It  may  be  mentioned  here  that  all  pegmatite  deposits  are  not 
worked  for  their  feldspar  contents,  some  serving  as  sources  of  other 
minerals,  such  as  mica,  quartz,  or  gems.  Their  value  as  spar  de- 
posits depends  on  the  quantity  and  purity  of  the  material  present. 

The  pottery  trade  demands  that  the  spar  be  free  from  iron-bearing 
minerals.  Muscovite  is  also  undesirable  on  account  of  the  diffi- 
culty encountered  in  grinding  it,  while  the  permissible  limits  for 
quartz  range  from  5  to  20  per  cent. 

In  quarrying  or  mining  some  sorting  is  often  necessary,  and  in 
those  states  lying  south  of  the  glaciated  area  the  deposit  may  be 
capped  with  residual  clay. 

Distribution  of  Feldspar  in  the  United  States.  —  In  the  United 
States  feldspar  quarries  are  operated  in  New  York,  Connecticut, 


MINOR  MINERALS 


323 


Maine,  Pennsylvania,  and  Maryland.  The  general  form  of 
deposit  is  similar  in  all  the  states,  but  those  worked  in  Penn- 
sylvania and  Maryland  are  albite  spar,  while  the  others  are 
potash  spar.  The  wall  rock  is  gneiss  or  schist. 

In  recent  years  feldspar  deposits  have  also  been  developed  in 
California,  Colorado,  and  Minnesota.1 

The  following  table  gives  the  composition  of  feldspar  from  a 
number  of  localities :  — • 

ANALYSES  OF  FELDSPARS 


1 

2 

3 

4 

5 

6 

7 

SiO2  .... 

64.7 

64.98 

65.40 

65.23 

69.63 

63.11 

65.95 

A1>O3       .     .     . 

18.4 

19.18 

18.80 

20.09 

12.30 

21.65 

18.00 

Fe2O3      .     .     . 

— 

.33 

tr. 

.71 

— 

— 

.12 

CaO  .... 

— 

tr. 

none 

none 

.95 

— 

1.05 

MgO.     .     .     . 

— 

.25 

none 

none 

none 

— 

tr. 

K,0    .... 

16.9 

12.79 

13.90 

11.60 

14.96 

14.10 

12.13 

Na2O       .     .     . 

— 

2.32 

1.95 

2.00 

.79 

1.46 

2.11 

Loss  on  ignition 

—  . 

.48 

.60 

.36 

.43 

.40 

— 

Total  .     .     , 

100.0 

100.33 

100.65 

99.99 

99.06 

100.72 

99.36 

1.  Theoretical  composition  of  pure  orthoclase  or  microcline.  2.  Norwegian  feldspar,  used  for 
porcelain.  3.  Pink  orthoclase-microcline  feldspar,  from  Bedford,  Ont.  Much  used  by  American 
potters.  4.  Cream-colored  orthoclase-microcline  feldspar,  Georgetown,  Me.  5.  White  orthoclase- 
microcline  feldspar,  South  Glastonbury,  Conn.  6.  Pearl-gray  orthoclase-microcline  feldspar, 
near  Batchellerville,  N.  Y.  7.  Pink  orthoclase-microcline  feldspar,  Bedford  Village,  N.  Y. 


ANALYSES  OF  FELDSPARS 


8 

9 

10 

ll 

13 

13 

14 

SiO   . 

65  33 

6462 

63  50 

6596 

6860 

4825 

7637 

A12O3       .     .     . 
Fe2O3      .     .     . 
CaO    .... 
MgO.     .     .     . 
K2O   .     .     . 
Na20.     .     .     . 
H2O   .... 
Loss  on  ignition 

20.96 
.71 
none 
none 
10.65 
1.37 

20.57 
tr. 
.14 
2.36 
1.94 
10.27 

22.39 
.36 
2.15 
none 
3.40 
6.27 

1.00 

19.53 
.24 
.18 

12.92 
1.13 

19.10 
.14 
tr. 
.28 
9.03 
2.09 

34.11J 
15.63 

1.98 

13.87 

.26 
none 
5.24 
3.74 
.30 

Total  .     .  '  y 

99.02 

99.90 

99.07 

99.96 

99.24 

99.97 

99.78 

8.  Light  yellow  orthoclase-microcline  feldspar,  North  Castle,  N.  Y.  9.  Soda  feldspar,  Chester 
County,  Pa.  10.  White  feldspar.  Embreeville,  Pa.  11.  Potash  feldspar,  Woodstock,  Md.  12.  Pot- 
ash-soda feldspar,  Henryton,  Md.  13.  Lime-soda  feldspar  (bytownite),  Point  Corundum,  near 
Duluth,  Minn.  Used  for  abrasives  and  filters,  but  not  for  p'ottery.  (All  analyses  from  Min. 
Res.,  U.  S.,  1906  :  1257,  1907.)  14.  Kinkle's  quarry,  Bedford,  N.  Y.,  No.  3  grade,  used  in  glass, 
but  not  for  pottery.  U.  S.  G.  S.,_Bull.  420. 

1  U.  S.  Geol.  Surv.,  Min.  Res.  1913:    149,  1914. 


324  ECONOMIC   GEOLOGY 

Canada.  —  Most  of  the  Canadian  production  is  derived  from 
the  province  of  Ontario,  the  principal  mines  being  located  in 
Frontenac  County,  about  20  miles  north  of  Kingston  (PL  XXXII, 
Fig.  2) .  The  feldspar,  which  is  often  of  a  deep  pink  color  and  high 
purity,  occurs  as  veins  in  the  pre-Cambrian  gneiss  of  that  region. 
Quartz  horses  and  veins  are  sometimes  present,  and  tourmaline  is 
likewise  found  in  patches.  While  the  spar  veins  are  very  abun- 
dant, not  all  are  of  sufficient  purity  to  be  workable.  Other 
deposits  have  been  worked  in  Ottawa  County,  Quebec,  one  mine 
near  Villeneuve  having  yielded  a  very  white  albite. 

Other  Foreign  Deposits.  —  Many  feldspar  deposits  are  worked  in  Europe, 
for  use  in  the  pottery  industry.  Those  of  Norway  and  Sweden  are  the 
largest  producers,  the  product  being  exported  in  considerable  quantity. 
In  this  connection  mention  may  be  made  of  Cornish  stone,  a  partly  weathered, 
coarse-grained  granite,  quarried  in  Cornwall,  England,  and  used  in  some 
quantity  by  the  potters  of  Europe  and  America. 

Uses  (1).  —  Feldspar  is  used  chiefly  as  a  flux  in  the  manufacture 
of  pottery,  electrical  porcelain,  and  some  enameled  wares.  For  all 
these  purposes  it  should  be  as  free  from  iron  as  possible,  but  some 
of  the  ground  commercial  spar  carries  as  much  as  15  to  20  per  cent 
free  quartz. 

Feldspar  is  also  employed  as  a  flux  or  binder  in  emery  and  car- 
borundum wheels,  and  to  some  extent  in  the  manufacture  of  opales- 
cent glass.  For  the  last  purpose  it  can  carry  more  quartz  and  mus- 
covite  than  pottery  spar,  and  does  not  have  to  be  as  finely  ground, 
50  to  60  mesh  being  sufficient. 

As  an  ingredient  of  scouring  soap,  feldspar  possesses  advantages 
over  quartz,  because  it  is  softer  and  less  liable  to  scratch  glass. 
Selected  feldspar  is  used  in  the  manufacture  of  artificial  teeth. 

The  possibility  of  using  feldspar  as  a  fertilizer,  because  of  its  potash 
contents,  has  been  suggested;  but  no  commercially  practicable  means 
of  extracting  the  desired  element  has  as  yet  been  found  (2). 

Production  of  Feldspar.  —  The  production  of  feldspar  from 
1909  to  1914  is  given  below.  The  crude  refers  to  that  sold  in 
the  unground  state,  but  all  spar  is  crushed  before  use. 


PLATE  XXXIII 


FIG.  1.  —  Stewart  graphite  mine,  near  Buckingham,  Que.    Rock  on  right,  graphitic 
gneiss.     On  left  at  farther  end  of  cut,  a  basic  igneous  rock.     (H.  Ries,  photo.) 


FIG.  2.  —  Lacey  mica  mine,  Ontario.     (Photo  loaned  by  Can.  Dept.  Mines.) 

(325) 


326  ECONOMIC  GEOLOGY 

PRODUCTION  OF  FELDSPAR,  1909-1914,  IN  SHORT  TONS 


YEAR 

CRUDE 

GROUND 

TOTAL 

Quantity 

Value 

Quantity 

Value 

Quantity 

Value 

1909     .... 
1910     .     . 
1911     .     . 
1912     .... 
1913     .... 
1914     .     .     . 

25,506 
24,655 
28,131 
26,462 
45,391 
85,905 

$  70,210 
81,965 
88,394 
89,001 
148,549 
263,476 

51,033 
56,447 
64,569 
60,110 
75,564 
49,514 

$354,392 
420,487 
490,614 
431,561 
628,002 
366,397 

76,539 
81,102 
92,700 
86,572 
120,955 
135,419 

$424,602 
502,452 
579,008 
520,562 
776,551 
629,873 

MARKETED  PRODUCTION  OF  FELDSPAR  IN  1914,  BY  STATES,  IN  SHORT  TONS 


STATE 

CRUDE 

GROUND 

TOTAL 

Quantity 

Value 

Quantity 

Value 

Quantity 

Value 

California 
Connecticut 
Delaware 
Maine 
Maryland 
New  Hampshire 
New  York     . 
North  Carolina 
Pennsylvania 
Virginia    .     . 

Total     .     . 

2,778 
11,099 

12,553 
5,867 

289 
15,420 
2,843 
2  35,056 

$  10,715 
42,965 
i 

30,925 
19,224 
i 
1,032 
43,153 
10,162 
2  105,300 

5,414 

17,510 
42 

2,778 
16,513 
i 

30,063 
5,909 

19,579 
15,420 
10,101 
35,056 

$  10,175 
83,291 

i 

194,560 
19,434 

i 

102.027 
43,153 
71,393 
105,300 

$  40,326 

163,635 
210 

19,290 

7,258 

100,995 
61,231 

85,905 

$263,476 

49,514 

$366,397 

135,419 

$629,873 

1  Included  in  Virginia.     2  Virginia  includes  Delaware  and  New  Hampshire. 


PRODUCTION  OF  FELDSPAR  IN  CANADA,  1912-1914 


YEAR 

QUANTITY, 
SHORT  TONS 

VALUE 

1912 
1913 
1914 

13,733 
16,790 
18,060 

30,916 
60,795 
70,824 

The  world's  production  was  supplied  by  the  United  States, 
Canada,  Belgium,  Italy,  Madagascar,  Norway,  Sweden,  and 
Germany. 

The  preceding  figures  do  not  include  feldspar  used  for  all 
purposes. 

Dealers  usually  divide  feldspar  into  the  following  three  grades: 

No.  1,  which  is  free  from  iron-bearing  minerals,  mostly  free  from 
muscovite,  and  contains  less  than  5  per  cent  quartz. 

No.  2,  which  is  largely  free  from  iron-bearing  minerals,  and  in 
the  potash  spar  usually  carries  15  to  20  per  cent  quartz. 


MINOR  MINERALS  327 

No.  3,  which  is  less  carefully  selected  and  may  carry  enough 
iron-bearing  minerals  to  render  it  unfit  for  pottery  purposes. 

Feldspar  free  from  quartz  is  much  sought  after  and  difficult 
to  obtain  in  large  quantities  in  the  United  States. 

The  average  price  in  1914  of  crude  feldspar  used  for  pottery  and 
enamel  ware  was  about  $3.07  per  short  ton  f.o.b.  ,while  the  aver- 
age price  of  the  ground  was  about  $7.40  per  short  ton  f.o.b.  mills. 

REFERENCES    ON   FELDSPAR 

1.  Bastin,  U.  S.  Geol.  Surv.,  Bull.  420,  1910.  (General  and  United  States.) 
2.  Cushman,  U.  S.  Dept.  Agric.,  Bur.  Plant  Industry,  Bull.  104,  1907. 
(Fertilizer  uses.)  3.  Day  and  Allen,  Amer.  Jour.  Sci.,  XIX:  98,  1905. 
(Thermal  properties.)  3a.  Galpin,  Ga.  Geol.  Surv.,  Bull.  30,  1915. 
(Ga.)  4.  Hopkins,  Ann.  Rept.  Pa.  State  College,  1898  to  1899,  Ap- 
pendix, Pt.  II.  5.  Mathews,  Md.  Geol.  Surv.,  Rept.  on  Cecil  Co.: 
217,  1902.  6.  Watson,  Min.  Res.  Va.,  1907:  275.  (Va.)  Also  forth- 
coming bulletin,  Va.  Geol.  Survey. 

FLUORSPAR 

Fluorspar,  or  fluorite  (CaF2),  contains  48.9  per  cent  fluorine  and 
51.1  per  cent  calcium.  Its  hardness  is  4,  its  specific  gravity,  3.18, 
and  it  has  a  pronounced  octahedral  cleavage.  Fluorite  shows  a 
variety  of  colors,  including  white,  green,  purple,  etc.  The  mineral 
is  commonly  found  in  veins  which  may  be  fissure  fillings  or  replace- 
ments, and  is  often  associated  with  ore  minerals,  especially  lead  and 
tin.  Limestone  is  the  most  important  wall  rock  of  the  American 
deposits,  but  in  some  districts  granites,  gneisses,  or  volcanic  rocks 
may  form  the  vein  wall. 

Distribution  in  the  United  States.  —  In  the  United  States  fluorite 
is  found  at  a  number  of  points  in  the  Piedmont  and  Appalachian 
areas  from  Maine  to  Virginia,  and  is  likewise  noted  (usually  in  small 
amounts)  in  many  metalliferous  veins  of  the  west;  but  the  most 
important  producing  districts  are  in  Kentucky  and  Illinois.  Colo- 
rado, Arizona,  and  Tennessee  are  also  to  be  included  in  the  produc- 
ing states. 

Kentucky  (3,  4) .  —  In  the  western  Kentucky  district,  which  is 
one  of  the  largest  producers  of  the  world,  the  fluorite  occurs  as  vein 
deposits  in  fault  fissures  cutting  limestones  (PI.  XXXIV,  and  Fig. 
112),  sandstones,  and  shales  of  Carboniferous  age.  The  minerals 


328 


ECONOMIC  GEOLOGY 


have  been  deposited  by  (1)  a  filling  of  the  fissure  cavity,  (2)  replac- 
ing the  wall  rock  of  the  fissure,  or  (3)  cementing  a  breccia  of  the 
same.  Associated  with  the  fluorspar  are  barite,  calcite,  galena, 
and  sphalerite,  as  well  as  other  minerals  in  smaller  amounts.  The 
different  minerals  may  occur  in  the  veins,  either  intimately  inter- 
grown  or  in  separate  bands;  in  some  cases,  however,  only  one  min- 
eral may  be  present  in  the  vein.  The  fault  fissures  strike  northeast 
and  northwest,  but  the  former  carry  more  fluorite. 


FIG.  112.  —  Section  of  Memphis  mine  group,  along  line  SS  of  PL.  XXXIV. 
(After  Fohs,  Ky.  Geol.  Sure.,  Bull.  9.) 

It  is  supposed  that  the  fluorite  has  been  deposited  by  thermal 
waters,  which  were  given  off  during  cooling  by  the  dikes  of  mica 
peridotite  which  are  found  in  the  district.  The  fissures,  fault 
planes,  and  dike  contacts  served  as  trunk  channels  along  which  the 
waters  ascended,  and  from  which  they  also  spread  out  into  the  ad- 
jacent rocks.  Weathering  has  produced  a  disintegration  of  the 
fluorite.  The  veins  show  a  maximum  width  of  36  feet  for  gravel 
ore  and  16  feet  for  lump  ore. 

The  product  of  the  veins  is  divided  into  lump,  representing  the 
coarse  product;  gravel,  which  is  the  naturally  or  artificially  disin- 
tegrated spar,  and  ground  fluorspar.  Washing  and  jigging  are 
necessary  to  separate  clay  and  associated  minerals.  Number  1 
fluorite  is  usually  white  and  carries  96  per  cent  or  more  of  calcium 
fluoride;  Number  2  grade  has  at  least  90  per  cent  calcium  fluoride 
and  under  4  per  cent  silica;  while  Number  3  carries  from  60  to  90 
per  cent  calcium  fluoride. 

Illinois.  —  Until  1898  the  mines  of  Hardin  and  Pope  counties, 
Illinois,  were  the  only  domestic  source  (1),  and  this  area  continues 


MINOR  MINERALS  329 

to  be  an  important  producer.  There  the  deposits  fill  fault  fissures 
in  Lower  Carboniferous  limestones  or  sandstones.  Dikes  of  mica 
peridotite  also  occur  in  the  district,  but  not  in  contact  with  the  veins. 
These  latter  in  some  places  attain  a  width  of  45  feet  and  a  proven 
depth  of  200  feet.  This  great  width  is  due  partly  to  enlargement  of 
the  fissure  by  solution,  and  partly  to  a  replacement  of  the  limestone 
walls.  In  the  limestone  footwall,  the  fluorspar  sometimes  forms  a 
solid  mass  from  2  to  12  feet  thick,  but  that  on  the  hanging  wall  is 
less  pure.  The  vein  filling  is  chiefly  fluorite  and  calcite,  while  as- 
sociated with  these  are  smaller  amounts  of  galena,  sphalerite,  and 
occasionally  pyrite  or  chalcopyrite.  It  is  significant  that  the 
galena  is  slightly  argentiferous. 

The  origin  of  the  fluorite  is  somewhat  doubtful,  but  Bain  (1)  be- 
lieves that  it  has  probably  been  derived  from  heated  waters  of  either 
meteoric  or  magmatic  origin  which  leached  the  mineral  from  some 
large  mass  of  low-lying  igneous  rocks  of  which  the  dikes  are  off- 
shoots. These  heated  ascending  solutions  are  thought  to  have 
carried  fluosilicates  of  zinc,  lead,  copper,  iron,  barium,  and  calcium. 
The  dissolved  compounds  were  probably  broken  up  by  cold  de- 
scending waters,  which  possibly  also  furnished  the  sulphur  to  com- 
bine with  the  metals. 

Colorado  (2) .  —  In  eastern  Colorado  fluorspar  occurs  in  consid- 
erable quantities  in  a  belt  extending  from  Boulder  County  to  Custer 
County.  The  veins,  in  most  cases,  cut  granites  and  gneisses  of 
pre-Cambrian  age  that  have  been  intruded  by  later  dikes,  especially 
of  quartz  porphyry.  Metalliferous  minerals  are  associated  with 
the  fluorite,  but  in  several  instances  the  latter  forms  most  of  the 
vein  filling.  The  deposits  have  thus  far  not  been  extensively  de- 
veloped, and  much  of  the  material  lies  rather  far  from  the  rail- 
road. The  three  producing  localities  are  Jamestown,  Boulder 
County;  Evergreen,  Jefferson  County;  and  near  Rosita,  Custer 
County. 

In  1913  shipments  were  made  from  an  interesting  vein  at  Wagon 
Wheel  Gap  (26).  The  fluorite  here  occupies  a  fissure  averaging 
3  feet  in  width  in  rhyolitic  tuffs  and  breccias.  It  is  associated 
with  hot  springs,  and  contains  small  quantities  also  of  barite, 
calcite,  quartz,  and  altered  pyrite,  the  latter  mostly  in  the  altered 
wall  rock.  Even  small  amounts  of  gold  and  silver  occur  in  the 
fluorite. 

New  Mexico  (2a). — Ten  miles  north  of  Deming,  fluorspar  is 
found  in  steeply  dipping  veins  cutting  monzonite  porphyry,  the 


330 


ECONOMIC  GEOLOGY 


latter  being  intrusive  in  Paleozoic  and  Cretaceous  sediments,  Fig. 
113.  The  veins  range  from  2  to  5  feet  in  width,  with  a  maximum 
of  12  feet  and  may  show  a  distinctly  banded  structure,  or  at  other 
times  consist  of  massive  spar  with  pockets  of  quartz.  Brecciation 


^4000  ft.  above  Sea  Level 

FIG.  113.  —  Map  and  sections  of  fluorspar  deposits,  Deming,  N.  Mex.  a,  Desert  fill; 
6,  andesitic  agglomerate;  c,  sandstone;  d,  limestone;  e,  intrusive  granite; 
/,  monzonite;  g,  basalt  dikes;  h,  rhyolite;  i,  fluorite  veins,  marked  1  and  2  on 
map.  (After  Darton  and  Burchard,  U.  S.  Geol.  Surv.,  Bull  470.) 

is  also  common.  The  partly  siliceous  veins  are  slightly  more 
resistant  than  the  surrounding  porphyry,  but  at  the  surface  the 
fluorspar  is  in  places  altered  to  calcium  carbonate. 

Other  States.- — Tennessee  (3,  5)  fluorspar  comes  from  Smith, 
Trousdale,  and  Wilson  counties  of  that  state;  while  that  obtained 
in  Arizona  (5)  is  mainly  from  the  Castle  Dome  district,  Yuma 
County. 


332  ECONOMIC  GEOLOGY 

Canada.  —  Fluorspar  is  known  to  occur  near  Madoc,  Hastings 
County,  Ont.,  and  also  in  Huntingdon  township,  but  the  output 
is  small. 

Other  Foreign  Deposits.  —  Next  to  the  United  States,  Great  Britain 
is  the  largest  producer,  the  fluorspar  of  Derbyshire  and  Durham,  associated 
with  lead-zinc  ores  of  the  Carboniferous,  serving  as  an  important  source 
of  supply.  Most  of  the  mineral  comes  from  the  tailings  of  lead  mines, 
and  the  gob  of  abandoned  workings. 

Some  idea  of  the  importance  of  the  industry  is  gained  from  the  fact  that 
the  1913  production  amounted  to  53,663  long  tons,  of  which  over  37  per  cent 
was  shipped  to  the  United  States. 

In  Germany  fluorspar  veins  are  worked,  especially  in  the  southern  Harz 
district,  Bavaria,  Black  Forest  and  Thuringian  Forest.  The  veins  may  be 
large,  and  contain  the  common  associates. 

Imports.  —  Considerable  gravel  spar  is  produced  as  tailings 
from  the  English  lead  mines  and  shipped  as  ballast  to  the 
United  States,  thus  competing  with  the  American  product  as 
far  west  as  Pittsburg.  It  is  high  in  silica  and  is  almost 
entirely  consumed  by  open  hearth  steel  makers.  The  esti- 
mated imports  for  1913  were  not  over  22,682  short  tons,  valued 
at  $71,463,  while  those  for  1914  were  10,205  short  tons  valued 
at  $38,943. 

These  imports  amount  to  about  22.3  per  cent  of  the  domestic 
gravel  spar  production. 

Cryolite.  —  This  mineral,  which  is  a  sodium-aluminum  fluoride, 
is  not  produced  in  the  United  States,  the  entire  supply  being 
imported  from  Ivigtut  on  the  south  coast  of  Greenland.1  The 
quantity  imported  for  consumption  in  the  United  States  in  1914 
was  4612  long  tons,  valued  at  $94,424,  or  an  average  price  of 
$20.47  per  ton.  Canada  imported  $33,487  worth  in  1913. 

Analyses  of  Fluorspar.  —  The  analyses  (2,  3),  given  on  page 
333,  will  indicate  the  variation  in  composition  of  the  American 
product. 

Uses.  —  Fluorspar  was  formerly  used  chiefly  for  making 
hydrofluoric  acid,  but  not  more  than  5  to  10  per  cent  of  the 
domestic  product  is  now  employed  for  this  purpose,  while  increas- 
ing quantities  are  sold  for  the  manufacture  of  opalescent  glass. 
The  greatest  demand  for  it,  however,  is  as  a  flux  in  iron  manu- 
facture, since  it  saves  from  3  to  5  per  cent  more  iron  than  lime- 
stone flux,  reduces  the  sulphur  and  phosphorus  contents,  and 

1  Mining  Magazine,  Apr.,  1916. 


MINOR  MINERALS 

ANALYSES  OF  FLUORSPAR 


333 


LOCALITY 

CaF2 

SiO» 

CaCOs, 
MgCOi 

Fe20s, 
AlzOi 

Hodge  Mines,  Ky  
Nancy  Hanks  Mines,  Ky.   .     . 
Gravel  Fluorspar             .     . 

98.30 
96.00 
95  08 

.21 
.71 
1  90 

.98 
3.29 

tr. 

Rosita,  Colorado    

86.75 
[60.9 
1  76.05 

9.3 

27. 
19.8 



4.2 
n.d. 
4  2 

^86.75 
T96.01 

8.60 
1.9 



4.46 

1.88 

Fairview,  111  

\84.25 
88.85 

2.98 
3.4 

10.28 

1.28 
1  45 

Mirage  N   Mex  

93  68 

4  68 

76 

74 

increases  the  tensile  strength  of  the  metal.  On  account  of  its 
valuable  reducing  properties,  it  is  also  used  in  making  spiegeleisen, 
in  foundry  work,  and  in  cupola  furnaces.  It  is  also  used  as  a  flux 
in  silver,  lead,  and  copper  smelters;  in  the  electrolytic  refining 
of  antimony  and  lead;  in  the  manufacture  of  enamels,  glazes,  and 
fireproof  ware,  for  apochromatic  lenses,  for  gems,  cheap  jewelry, 
paper  weights,  and  for  carbon  electrodes  for  flaming  arc  lamps. 
Its  use  as  a  flux  in  cement  manufacture  has  been  discontinued. 
Fluorspar  for  iron  and  steel  making  should  contain  at  least  80  per 
cent  CaF2,  and  for  most  chemical  purposes  at  least  95  per  cent 
CaF2. 

Production  of  Fluorspar.  —  The  table  on  page  334  gives  the 
quantity  and  value  of  fluorspar  marketed  from  1912  to  1914. 

The  fluorspar  is  prepared  for  market  by  hand  sorting,  crush- 
ing, jigging,  and  sometimes  fine  grinding.  The  grades  produced 
are: — 

1.  American  lump  No.  1,  with  under  1  per  cent  silica,  and  sold 
mainly  to  glass,  enameling,  and  chemical  industries. 

2.  American  lump  No.  2,  which  includes  colored  spar  and  may 
run  as  high  as  4  per  cent  silica,  though  usually  sold  under  a  3  per 
cent  guaranty.     It  is  used  by  blast  furnaces  in  the  production  of 
ferrosilicon  and  ferromanganese,  and  in  basic  open   hearth  steel 
furnaces. 

3.  Gravel    spar,    including    all   with   over    4  per  cent  silica, 
and  spar   mixed   with    calcite.      It   is   used  in  iron  and  brass 
foundries. 


334  ECONOMIC  GEOLOGY 

FLUORSPAR  MARKETED  IN  1912-1914,  IN  SHORT  TONS 


STATE 

GRAVEL 

LUMP 

GROUND 

TOTAL 
QUAN- 
TITY 

TOTAL 
VALUE 

Quantity 

Value 

Quan- 
tity 

Value 

Quan- 
tity 

Value 

1912 
Illinois  .... 
Kentucky  . 
Other  states  • 

Total.     .     .     . 

1913 
Illinois  .... 
Kentucky  . 
Other  states  1.     . 

Total      .     .     . 

1914 
Illinois  .... 
Kentucky  .     . 
Other  states   .     . 

Total      .     .     . 

}  97,150 
2,135 

$565,784 
12,510 

5315 

$36,553 

11,945 

$154,316 

114,410 
2,135 

756,653 
12,510 

99,285 

J  91,663 
10,104 

$578,294 

525,456 
71,568 

5315 
5676 

$36,553 
39,059 

11,945 
8,137 

$154,316 
100,203 

116,545 

/  85,854 
\  19,622 
10,104 

$769,163 

550,815 
113,903 
71,568 

101,767 

}  77,048 
2  2,228 

$597,024 

397,913 
14,992 

5676 

8842 

2 

$39,059 
74,708 

2 

8,137 
6,998 

$100,203 

82,428 

$115,580 

(73,811 
\  19,077 
2,228 

$736,286 

426,063 
128,986 
14,992 

79,276 

$412,905 

8842 

$74,708 

6,998 

$82,428 

95,116 

$570,041 

1  Includes  Colorado,  New  Hampshire,  New  Mexico;   1913:  Arizona  in  addition; 
1914:   Colorado  and  New  Hampshire. 

2  Lump  spar  included  with  gravel. 

REFERENCES   ON   FLUORSPAR 

1.  Bain,  U.  S.  Geol.  Surv.,  Bull.  255,  1905;  also  Burchard,  Eng.  and  Min. 
Jour.,  Dec.  2,  1911.  (111.)  2.  Burchard,  U.  S.  Geol.  Surv.,  Min. 
Res.  for  1908.  (Colo.)  2a.  Darton  and  Burchard,  U.  S.  Geol.  Surv., 
Bull.  470,  1911.  (N.  Mex.)  26.  Emmons  and  Larsen,  Econ.  Geol., 
VIII:  235,  1913.  (Colo.)  3.  Fohs,  Ky.  Geol.  Surv.,  Bull.  9,  1907. 
(Ky.  and  general.)  4.  Fohs,  Amer.  Inst.  Min.  Engrs.,  Trans.  XL: 
261,  1910,  and  Econ.  Geol.,  V:  377,  1910.  (Ky.  spar  and  use  in  iron 
industries.)  5.  Pratt,  U.  S.  Geol.  Surv.,  Min.  Res.,  1901:  879,  1902, 
(Ariz.)  5a.  de  Schmid,  Can.  Mines  Branch,  Sum.  Rept.,  1911:  117. 
1912.  (Ont.)  6.  Ulrich  and  Smith,  U.  S.  Geol.  Surv.,  Prof.  Pap.  36, 
1905.  (Ky.)  7.  Watson,  Va.  Geol.  Surv.,  Bull.  1:  42,  1905.  (Va.) 


FOUNDRY    SANDS 

Definition.  —  Under  the  term  foundry  sand  there  are  included 
(1)  sands  for  making  the  mold  proper  into  which  the  metal  is  cast, 
and  (2)  core  sand,  utilized  for  making  the  cores  which  occupy  the 
hollow  spaces  of  the  cast  piece. 

The  molding  sands  proper  are  usually  of  finer  texture  and  more 
loamy  character  than  the  core  sands,  still  the  two  grades  overlap, 
and  both  show  considerable  range  of  texture.  In  selecting  molding 
sands,  the  fine-grained  ones  are  used  for  small  castings,  while  the 


MINOR  MINERALS 


335 


coarser  grades  are  employed  for  heavy  castings.  The  core  sands 
have  but  little  cohesiveness,  owing  to  their  lack  of  clayey  matter, 
and  hence  require  the  addition  of  an  artificial  binder. 

Requisite  Properties.  —  The  requisite  physical  qualities  of  foun- 
dry sands  are:  1.  sufficient  cohesiveness  to  make  the  grains  cohere 
when  pressed  together  to  form  the  parts  of  the  mold,  the  deficiency 
in  this  respect  in  core  sands  being  supplied  by  artificial  binders; 
2.  sufficient  refractoriness  to  prevent  extensive  fusion  in  the  sand 
when  exposed  to  the  heat  of  the  molten  metal;  3.  texture  adapted 
to  the  grade  of  casting  to  be  poured  in  it;  4.  sufficient  porosity 
and  permeability  to  permit  the  escape  of  the  gases  given  off  by  the 
cooling  metal;  5.  durability,  or  sufficient  length  of  life,  to  permit 
as  much  of  the  sand  as  possible  being  used  over  again. 

The  laboratory  examination  of  a  molding  sand  might  properly 
include  the  determination  of  (1)  its  texture  (by  mechanical  analy- 
sis), (2)  porosity,  (3)  permeability  (by  aspirator  method),  (4)  average 
fineness  (by  aspirator  method),1  (5)  tensile  strength,  and  (6)  refrac- 
toriness. 

Chemical  analyses  of  foundry  sands  are  in  most  cases  of  little 
value,  mainly  because  they  shed  no  light  on  the  physical  properties. 
A  few  are,  however,  given  below :  — 

CHEMICAL  ANALYSES  OF  FOUNDRY  SANDS 


1. 

2. 
3. 

4. 

5. 
6. 

7. 

8. 
9. 
10. 
11. 
12. 

SiO2 

A1203 

Fe203 

CaO 

MgO 

K2O 

Na2O 

TiO2 

H2O 

MOIST 

81.59 
66.12 
79.36 
79.38 

71.60 

86.80 
84.28 

79.41 
57.63 

84.86 
82.90 
81.57 

6.46 
16.54 
9.36 
9.38 

11.49 
3.05 
4.50 

12.47 
10.03 
7.03 
8.21 
11.52 

4.94 
4.46 
3.18 
3.98 

7.81 
5.32 
6.10 

.80 
.88 
2.18 
2.90 
2.74 

.14 
.40 
.44 
1.40 

.65 
.15 

tr. 

.99 
11.16 

.62 
.62 
1.49 

.22 
.22 
.27 
.54 

.95 
.65 
.72 

.81 
5.63 
.98 
.00 
.18 

1.19 
2.67 
2.19 
1.80 

1.42 

.83 
.91 

1. 

. 
Un< 
Un< 

.59 
.35 
1.54 
1.04 

1.27 
.04 
.39 

56~~ 
01 
let. 
let. 

1.90 
.14 
.34 
.44 

1.63 
4.90 
2.02 
2.50 

1.46 
4.15 
.74 
.80 

4.00 
3.25 
3.10 

3.96 
14.66  2 
2.20 

2.85 
2.50 

1.  Fine  sand  for  light  castings,  Richmond,  Va.  2.  Coarse,  gravelly  core 
sand,  Richmond,  Va.  3.  Stove  plate  sand,  Albany,  N.  Y.  4.  Stove 
plate  sand,  Newport,  Ky.  5.  "  Philadelphia"  brass  sand.  6.  Lumberton, 
N.  J.,  brass  sand  (mild).  7.  Lumberton,  N.  J.,  brass  sand  (strong).  8. 
Upper  sand  bed,  Rockton,  111.  9.  Lower  sand  bed,  Rockton,  111.  10. 
Sand  for  medium  weight  castings.  11.  Coarse  sand  for  heavy  castings. 
12.  Stove  plate  sand,  Conneaut,  O.  All  quoted  from  Ref.  6. 

1  The  average  fineness  may  be  determined  in  other  ways,  but  these  are  less  ac- 
curate. See  Ref.  6.  2  Includes  CO2. 


336 


ECONOMIC  GEOLOGY 


The  following  table  gives  the  mechanical  analysis,  specific  gravity, 
and  porosity  of  a  number  of  samples  of  foundry  sand. 


PHYSICAL  TESTS  OF  FOUNDRY  SANDS 


e 

5 

No. 

PER  CENT  RETAINED  ON 

CLAY 

SPECIFIC  GRAVITY 

02 
1 

1 
K 
H 

£ 

1  AVERAGE  SIZE  OF  GR^ 
IN  TERMS  OF  SIEVES 
ASPIRATOR  METHOD 

20 

MESH 

40 

MESH 

60 

MESH 

80 

MESH 

100 

MESH 

250 

MESH 

1. 

6.84 

6.61 

40.09 

8.98 

23.82 

12.56 

1.06 

2.68 

36.2 

91 

2. 

.96 

12.42 

34.41 

4.31 

7.50 

18.29 

22.06 

2.61 

38.8 

714 

3. 

.30 

.77 

4.52 

1.63 

5.35 

57.95 

29.44 

2.59 

40.9 

770 

4. 

4.69 

13.34 

23.96 

5.01 

11.95 

18.22 

22.79 

2.66 

45.0 

222 

5. 

.09 

.45 

1.51 

.31 

.74 

66.79 

30.08 

2.67 

42.2 

1429 

6. 

.13 

.59 

20.10 

5.81 

15.89 

33.35 

24.09 

2.62 

— 

— 

7. 

.33 

.18 

.55 

.24 

5.47 

87.92 

5.36 

2.65 

43.0 

344 

8. 

2.51 

6.16 

16.49 

4.74 

11.30 

32.37 

26.39 

2.62 

42.9 

361 

9. 

.27 

.54 

1.21 

.32 

1.21 

69.46 

26.97 

— 

— 

— 

10. 

.08 

.20 

.17 

.00 

.14 

87.56 

11.82 

2.7 

46.7 

714 

11. 

1.51 

1.26 

1.27 

.56 

6.27 

71.69 

16.52 

— 

— 

— 

12. 

42.48 

12.90 

6.16 

.85 

1.70 

8.58 

26.44 

— 

— 

— 

13. 

3.03 

1.41 

.97 

.40 

2.61 

48.32 

41.87 

— 

— 

— 

14. 

— 

.36 

6.56 

3.52 

21.22 

64.84 

2.56 

— 

— 

— 

15. 

.4 

16.54 

56.24 

5.60 

5.20 

2.60 

13.34 

2.58 

40.41 

— 

16. 

1.32 

14.02 

28.68 

5.62 

10.24 

14.12 

25.02 

2.55 

39.52 

— 

17. 

18. 

.04 
4.5 

.06 
32.0 

.12 
23.0 

.06 
16.0 

.12 
9.5 

80.12 

19.22 

2.66 
2.613 

43.43 
45.1 

15 

19. 

5.5 

25.5 

11.5 

14.5 

12.0 

31 

— 

39.5 

— 

1.  Fine  core  sand,  Jackson,  Mich.  2.  Sand  for  general  work,  Zanesville, 
O.,  district.  3.  Riverside,  Mich.  4.  Core  sand,  Niles,  Mich.  5.  Stove 
plate  sand,  Conneaut,  O.  6.  Sand  for  general  work,  Vineland,  Mich.  7. 
Leoni,  Mich.  8.  Sand  for  heavy  work,  Battle  Creek,  Mich.  9.  No.  5 
sand,  Newport,  Ky.  10.  No.  3  sand,  Akron,  O.  Nos.  1-10  quoted  from 
Ref.  6.  11.  Sand  for  general  work,  Manchester,  Va.  12.  Coarse  sand, 
Richmond,  Va.  13.  Petersburg,  Va.  Nos.  11-13  quoted  from  Ref.  6.  14. 
Sand  for  small  castings,  Berlin,  Wis.  15.  Core  sand  for  heavy  castings, 
Janesville,  Wis.  16.  Sand  for  heavy  castings,  Kenosha  County,  Wis. 
17.  No.  4  sand,  for  malleable  and  gray  iron,  and  brass,  Waterford,  111. 
Nos.  14-17  quoted  from  Ref.  4.  18.  Lumberton,  N.  J.  19.  Strong  sand, 
Hainespoit,  N.  J.  Nos.  18-19,  Ref.  2. 


MINOR  MINERALS  337 

Distribution  in  the  United  States.  —  Many  thousands  of  tons  of 
foundry  sand  are  used  annually  by  foundries,  scattered  all  over 
the  United  States.  In  most  cases  these  represent  natural  mixtures, 
but  for  some  grades  of  work,  especially  steel  casting,  artificial  mix- 
tures of  quartz,  clay,  etc.,  are  used. 

Sands  for  cores  and  molds  for  general  work  are  widely  distributed 
and  obtainable  from  many  surface  formations,  usually  of  recent  age; 
but  the  finer-grained  sands,  such  as  are  required  for  stove  plate  and 
brass  casting,  are  of  rarer  occurrence.  The  regions  around  Albany, 
New  York,  Conneaut,  Ohio,  Newport,  Kentucky,  Valparaiso,  In- 
diana, etc.,  are  noted  for  their  supplies  of  the  finer  grades  of  mold- 
ing sands.  New  Jersey  is  also  an  important  producer,  but  there 
the  sand  is  obtained  largely  from  Cretaceous  and  Tertiary  deposits. 
In  the  digging  of  molding  sand,  careful  sorting  is  sometimes  neces- 
sary, the  deposit  of  good  sand  being  often  thin,  or  of  irregular 
thickness,  and  interbedded  with  other  sands  of  no  value,  although 
closely  resembling  the  good  material. 

The  literature  on  molding  sands  is  not  extensive. 

The  value  of  molding  sand  produced  in  the  United  States  in  1914 
is  reported  as  $1,756,383,  but  these  figures  are  probably  only  ap- 
proximate. 

REFERENCES  ON  FOUNDRY  SANDS 

1.  Newland,  Amer.  Foundrymen's  Assoc.,  1915.  (Albany  sand.)  2.  Kiimmel 
and  Parmelee,  N.  J.  Geol.  Surv.,  Ann.  Kept.  1904:  189,  1905.  (General 
and  N.  J.)-  3.  Merrill,  Non-Metallic  Minerals:  New  York,  Wiley  and 
Sons.  (General.)  4.  Ries  and  Gallup,  Wis.  Geol.  and  Nat.  Hist.  Surv. 
Bull.  XV:  197,1906.  (Wis.  and  General.)  5.  Ries,  Metal  Industry 
June  and  July,  1908.  (Relative  advantages  of  chemical  and  physica, 
examination.)  6.  Ries  and  Rosen,  Mich.  Geol.  Surv.,  Ann.  Rept.  for 
1907.  (General  and  Mich.).  7. .  Watson,  Min.  Res.  Va.,  Lynchburg, 
1907:394.  (Va.).  8.  Condit,  Jour.  Geol.,  XX:  152,1912.  (O.). 


FULLER'S   EARTH 

Properties.  —  Fuller's  earth  (7)  may  be  regarded  as  a  peculiar 
type  of  clay  which  has  a  high  absorbent  power  for  many  substances, 
on  which  account  it  is  of  value  for  decolorizing  oil  and  other  liquids. 
Its  color  and  chemical  composition  are  variable,  and  its  specific 
gravity  ranges  from  1.75  to  2.5.  The  quantitative  analysis  shows 
it  to  differ  chiefly  from  common  clay  in  having  a  relatively  higher 
percentage  of  combined  water. 

The  following  analyses  represent  the  composition  of  fuller's  earth 


338 


ECONOMIC   GEOLOGY 


from  different  localities,  but  it  should  be  emphasized  that  they  are 
of  little  value  in  judging  the  quality  of  the  earth :  — 

CHEMICAL  ANALYSES  OF  FULLER'S  EARTH 


I 

II 

in 

IV 

V 

VI 

VII 

Si02     .     . 

47.10 

62.83 

67.46 

58.72 

74.90 

54.32 

63.19 

A1203   .     . 

16.27 

10.35 

10.08 

16.90 

10.25 

18.88 

18.76 

Fe2O3  .     . 

10.00 

2.45 

2.49 

4.00 

1.75 

6.50 

7.05 

CaO     .     . 

2.63 

2.43 

3.14 

4.06 

1.30 

1.00 

78 

MgO    .     . 

3.15 

3.12 

4.09 

2.56 

2.30 

3.22 

1.68 

K2O     .     . 

— 

.74 

— 

2.11 

1.75 

4.21 

.21 

Na20  .     . 

— 

.20 

— 

— 

— 

— 

1.50 

H20     .     . 

20.85 

7.72 

5.61 

8.10 

5.80 

— 

7.57 

Moisture  . 

— 

6.41 

6.28 

2.30 

1.70 

11.86 

— 

Total  ,. 

100.00 

96.25 

99.15 

98.45 

99.75 

99.99 

100.74 

I.  Woburn  sands,  Eng.  (Yellow.)  II.  Gadsden  County,  Fla.  III. 
Decatur  County,  Ga.  IV.  Fairburn,  S.  Dak.  V.  Sumter,  S.  Ca.  VI. 
Bakersfield,  Calif.  VII.  Alexander,  Ark.  All  quoted  from  Ref.  7. 

The  cause  of  the  bleaching  power  of  fuller's  earth  still  remains  to 
be  explained,  but  Parsons  (3)  has  suggested  that  the  phenomenon 
is  one  of  simple  adsorption.  Lime  carbonate  seems  to  injure  the 
bleaching  power  of  the  earth,  and  in  some  cases  appears  to  be  coun- 
teracted somewhat  by  acid  treatment.  A  practical  test  affords  the 
only  satisfactory  method  of  determining  the  value  of  fuller's  earth. 

Distribution  in  the  United  States  (1,  3,  7).  —  In  former  years 
nearly  all  of  the  fuller's  earth  used  in  the  United  States  was  imported 
from  England,  where  large  deposits  of  this  material  exist;  but  oc- 
currences are  now  known  in  a  number  of  states,  including  Florida, 
Georgia,  Alabama,  Arkansas,  Colorado,  South  Carolina,  etc. 

At  most  localities  the  earth  is  found  interbedded  with  sands  or 
clays,  which  may  sometimes  differ  from  it  but  little  in  appearance. 

Fuller's  earth  is  not  confined  to  any  particular  formation,  but  the 
known  deposits  occur  in  sedimentary  rocks  ranging  from  the  be- 
ginning of  the  Mesozoic  up  to  the  Pleistocene.  In  Gadsden 
County,  Florida  (5,8)  and  in  Decatur  County,  Georgia  (8),  for 
example,  it  is  obtained  from  the  upper  Oligocene  of  the  Tertiary, 
the  former  locality  being  the  most  important  in  the  country.  The 
earth  from  this  region  is  used  for  bleaching  mineral  oils. 

Foreign  Deposits.1  —  The  best  known  foreign  deposits  are  those  of  Eng- 
land.    They  are  worked  chiefly  in  the  Lower  Cretaceous  at  Woburn  Sands, 
and  in  the  Lower  Oolite  (Jurassic)  at  Bath.     The  German  deposits,  though 
1  Dammer  and  Tietze,  Nutzbaren  Mineralien,  II:  419,  1913. 


MINOR   MINERALS 


339 


of  low  yield,  are  interesting  because  those  of  the  most  important  or  Wester- 
wald  district  are  a  weathering  product  of  basalt,  while  some  of  the  Saxon 
ones  come  from  the  decay  of  gabbro  and  amphibolite. 

Uses.  —  Fuller's  earth  was  originally  used  for  fulling  cloth, 
but  in  this  country  its  employment  for  this  purpose  is  small,  the 
chief  use  being  for  bleaching,  clarifying,  or  filtering,  fats,  greases, 
and  oils.  It  has  also  been  employed  in  the  manufacture  of  pig- 
ments for  printing  wall  papers,  for  the  detection  of  certain  color- 
ing matters  in  some  food  products,  and  as  a  substitute  for 
talcum  powder. 

For  treating  mineral  oils  the  carefully  dried  earth  is  placed  in 
cylinders,  and  the  oil  allowed  to  filter  slowly  through  it,  the  result 
being  that  the  first  oil  comes  out  water  white.  In  the  treatment 
of  vegetable  oils,  these  are  heated  in  large  tanks  to  above  212°  F., 
from  5  to  10  per  cent  oil  added,  and  after  strong  stirring,  the  mix- 
ture put  in  a  filter  and  the  discolored  oil  strained  out. 

Production  of  Fuller's  Earth.  —  Fuller's  earth  was  dixcovered 
in  the  United  States  in  1891  near  Alexander,  Ark.  It  was  sub- 
sequently accidentally  discovered  near  Quincy,  Fla.,  and  this 
state  has  remained  the  leading  producer.  The  domestic  output 
has  never  been  large,  and  much  is  still  imported  from  England. 


PRODUCTION  OF  FULLER'S  EARTH  IN  UNITED  STATES,   1912-1914 


YEAR 

SHORT  TONS 

VALUE 

AVERAGE  PRICE 
PER  TON 

1912                          .     .     . 

32,715 

$305,522 

$9  34 

1913    
1914 

38,594 
40,981 

369,750 
403,646 

9.58 
9  85 

FULLER'S  EARTH  IMPORTED  FOR  CONSUMPTION  INTO  UNITED  STATES,  IN 

SHORT  TONS 


-XEAB 

UNWROUGHT  OR 
UNMANUFACTURED 

WROUGHT   OR 
MANUFACTURED 

TOTAL 

Quan- 
tity 

\alue 

Average 
Price 
per  Ton 

Quan- 
tity 

Value 

Average 
Price 
per  Ton 

Quan- 
tity 

Value 

Average 
Price 
per  Ton 

1912  .     . 
1913  .     . 
1914  .     . 

1970 
1916 
1468 

$11,619 
12,344 
9,283 

$5.90 
6.44 
6.32 

17,139 
16,712 
23,509 

$133,718 
133,657 
185,800 

$7.80 
8.00 
7.  90 

19,109 
18,628 
24,977 

$145,337 
146,001 
195,083 

$7.61 
7.84 
7.81 

340  ECONOMIC   GEOLOGY 


REFERENCES    ON    FULLER'S    EARTH 

1.  Branner,  Amer.  Inst.  Min.  Engrs.,  XLIII:  520,  1913.  (Ark.)  la. 
Day,  Jour.  Frank.  Inst.,  CL,  1900.  (Distribution.)  16.  Gilpin  and 
Bransky,  U.  S.  Geol.  Surv.,  Bull.  475,  1911.  (Diffusion  of  oil  through 
earth.)  2.  Merrill,  Guide  to  Study  of  Non-metallic  Minerals:  337, 
1901.  (General.)  3.  Parsons,  Bur.  Mines,  Bull.  71,  1913.  (Proper- 
ties.) 4.  Porter,  U.  S.  Geol.  Surv.,  Bull.  315:  268,  1807.  (Properties 
and  tests.)  5.  Ries,  U.  S.  Geol.  Surv.,  17th  Ann.  Kept.,  Pt.  Ill  (ctd.): 
877.  (General.)  6.  Ries,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVII: 
333,  1898.  7.  Ries,  Clays,  Occurrence,  Properties,  and  Uses,  2d  ed.: 
516,  1908.  (General.)  7a.  Sellards,  Fla.  Geol.  Surv.,  1st  Ann.  Rept. 
33,  1908,  and  2d  Ann.  Rept.:  257,  1909.  (Fla.)  8.  Vaughan,  U.  S. 
Geol.  Surv.,  Min.  Res.,  1901:  922,  1903.  (Ga.  and  Fla.)  9.  Wesson, 
Min.  and  Eng.  World,  XXXVII:  667,  1912.  (Bleaching  oils.) 


GLASS    SAND 

Glass  sand  is  obtained  from  quartzose  sands,  sandstones,  or 
quartzites.  When  sand  is  employed,  it  is  sometimes  necessary  to 
put  it  through  a  washing  process  in  order  to  separate  the  impurities, 
while  in  the  case  of  sandstone  or  quartzite,  at  least  a  preliminary 
crushing  and  screening  are  usually  necessary. 

Chemical  Composition.1  —  Since  silica  is  the  major  ingredient  of 
the  sand,  it  influences  the  character  of  the  ware  to  a  marked  degree. 
Sand  with  impurities  is  therefore  to  be  avoided,  especially  if  it  is 
to  be  used  for  the  higher  grades  of  glassware.  Chemical  analysis  of 
almost  any  sand  may  show  at  least  traces  of  iron  oxide,  alumina, 
titanium  oxide,  lime,  magnesia,  and  organic  matter,  but  most  of 
these  are  included  in  mineral  grains  other  than  quartz. 

Iron  oxide,  even  in  small  amounts,  colors  the  glass  green,  and  is 
avoided  by  a  selection  of  the  whitest  sand,  although  whiteness  does 
not  necessarily  indicate  freedom  from  impurities.  Washing  may 
remove  much  of  the  iron,  and  the  iron  color  may  also  be  counter- 
acted to  some  extent  by  the  addition  of  arsenic.  Magnesia  causes 
trouble  by  rendering  the  batch  less  fusible,  but  it  is  more  apt  to  be 

1  Frink  (Ref .  14)  believes  that  many  of  the  views  held  regarding  allowable  limit 
of  MgO  and  Al^Os  are  incorrect,  and  these  substances  are  less  harmful  than  ia  com- 
monly imagined. 


MINOR  MINERALS  341 

introduced  through  the  limestone  than  the  sand.     Clay  is  undesir- 
able, since  it  tends  to  cloud  the  glass. 

CHEMICAL  ANALYSES  OF  GLASS  SANDS 


SiO2 

AUO3 

Fe,0s 

CaO 

MgO 

TOTAL 

1.  Ottawa,  LaSalle  County, 

111     ....... 

99.45 

.30 

.13 

tr. 



99.88 

2    Utica  111       .     .  '  f    .     . 

99.57 

.283 

.0903 

.0197 

.002 



99.97 

3.  Klondike,  Mo.  .     .     .     . 

99.97 

.03 

— 

100.00 

4.  Grays  Summit,  Mo.    . 

99.839 

— 

.0014 

— 

.T- 

HO 

.154 

99.9944 

5.  Everton,  Boone  Co.,  Ark. 

99.55 

.13 

.09 

— 



— 

99.77 

6.  Flora,  Grant  Co.,  Wis.   . 

99.17 

.25 

.22 

— 



99.64 

Ign- 

7    Coxville  Ind 

98.61 

.74 

.22 

.12 

tr. 

.32 

100.01 

Und. 

8.  Tip  Top,  Ky.  (.elected)  . 

98.87 

.21 

.08 

.24 

.12 

.48 

100.00 

9    Massillon  O 

97.50 

1.50 

.50 



.50 



100.00 

10.  Niles,  O  

99.915 

.062 

.0019 

.021 

tr. 

— 

99.999 

11.  Berkeley,  W.  Va.    (Oris- 

kany  sandstone) 

98.99 

.7717 

.0383 

— 

— 

— 

99.80 

12.  4  m.  from  Hancock,  W.Va. 

(Medina  sandstone)     . 

99.30 

.5186 

.0314 

— 

— 

— 

99.85 

13.  Columbia,  Pa.  (Oriskany) 

99.5044 

.1337 

.2989 

Loss 

99.9999 

etc. 

.062 

14.  Cheshire,    Mass.    (Cam- 

brian)    

99.46 

.48 

.06 

100.00 

15.  Lewiston,  Pa.  (Oriskany) 

98.84 

.17 

.34 

tr. 

tr. 

Ign. 

99.58 

.23 

16.  Hanover,  N.  J.  (Tertiary) 

97.705 

.755 

.15 

.955 

.442 

100.007 

17.  Clayton,  la.  (Ordovician) 

98.85 

.46 

.995 

.21 

Loss 

99.999 

etc. 

.384 

18.  W.  Vienna,  N.  Y.  (Pleis- 

tocene)       

98.6 

.17 

.23 

tr. 

99.00 

Nos.  1-6,  Ref.  3;  Nos.  7-10,  Ref.  4;  Nos  11-12,  Ref.  10. 

Physical  Properties  (3).  —  Contrary  to  the  belief  of  glass  manu- 
facturers that  rounded  grains  are  best,  much  good  glass  is  made 
from  sands  of  angular  or  subangular  grain.  Uniformity  of  grain 
is  highly  desirable,  and  should  range  between  30  and  120  mesh.  If 
larger  than  30  mesh,  the  sand  is  more  difficult  to  fuse;  while  if  finer 
than  120  mesh,  it  is  said  to  "  burn  out  "  in  the  batch. 


342 


ECONOMIC   GEOLOGY 


Few  mechanical  analyses  of  glass  sands  have  been  published, 
but  the  following  will  serve  to  show  the  texture  of  several  from  dif- 
ferent localities  (2,  3). 

MECHANICAL  ANALYSES  OF  GLASS  SANDS 


LOCALITY 

SAMPLE 

PASSES 
20  MESH 

PASSES 
40  MESH 

PASSES 
60  MESH 

PASSES 
100  MESH 

Ottawa,  111.    .     . 

Finest  grained  .     . 

100 

100 

92 

25 

Ottawa,  111.    .     . 

Coarsest  grained 

99 

6 

1- 

0 

Ottawa,  111.     .     . 

Crude,  direct  from 

99  + 

23 

3 

pit. 

1- 

Utica,  111.  .     .     . 

Crude  from  car 

99  + 

45 

11 

3 

Klondike,  Mo.    . 

Extra  qualtiy  . 

100 

90 

15 

1 

Grays  Summit, 

Finished  product 

100 

92 

25 

2 

Mo. 

Grays  Summit, 

Crude,       from 

100 

8& 

55 

1- 

Mo. 

quarry. 

Crystal  City,  Mo. 

Prepared      .     .     . 

99  + 

23 

13 

1 

Crystal  City,  Mo. 

Average  mine  run 

100 

55 

20 

1 

Berkeley  Springs, 

Crushed  sandstone, 

100 

98 

25 

1- 

W.  Va. 

finished  product 

Everton,  Ark. 

Not  worked      .     . 

99  + 

97 

50 

10 

Flora,  Wis.     .     . 

Not  worked      . 

99  + 

80 

40 

15 

Distribution  of  Glass  Sand.  —  Sand  for  glass  making  is  obtained 
from  a  number  of  different  geological  formations,  ranging  from 
Cambrian  to  Pleistocene.  Those  obtained  from  the  Pleistocene 
deposits,  as  in  New  York  (12),  are  not  as  a  rule  of  high  purity,  but 
those  from  the  Tertiary  and  Cretaceous  formations  are  of  better 
quality.  In  New  Jersey  there  are  extensive  pits  in  the  Tertiary, 
around  Bridgeton  (11),  the  material  being  used  in  the  glass  works 
of  southern  New  Jersey  and  southeastern  Pennsylvania.  Large 
pits  have  also  been  opened  in  the  Raritan  formation  of  the  Creta- 
ceous along  the  Severn  River  in  Maryland.  The  Oriskany  sandstone 
is  found  to  be  of  high  purity  in  West  Virginia  between  Berkeley 
Springs  and  a  point  on  the  border  near  Hancock,  Maryland,  the 
locality  having  been  worked  for  a  number  of  years  (10).  Sand- 
stones of  the  same  age  are  also  worked  in  Pennsylvania  (6,  8). 

The  glass-sand  industry  of  Illinois  (2),  is  developed  mainly  in  La 
Salle  County,  the  rock  used  being  the  St.  Peter  (Ordovician)  sand- 
stone. Much  of  it  is  very  soft.  Sandstone  of  similar  age  is  worked 
in  Missouri  (1,  2),  in  a  belt  between  Klondike  on  the  Missouri  River 


MINOR  MINERALS 


343 


and  Crystal  City  on  the  Mississippi  River.  Indiana  (4)  contains 
sandstone  suitable  for  glass  manufacture  in  the  Silurian,  Devonian, 
Carboniferous,  and  Tertiary  formations,  but  most  of  it  comes 
from  the  Mansfield  sandstone  of  the  Carboniferous  in  the  south- 
western part  of  the  state.  Beds  of  high-grade  sandstone  occur  in- 
terbedded  with  Silurian  limestones  in  northwestern  Ohio  (4),  but 
the  most  important  deposits  are  found  in  the  Mississippian,  Potts- 
ville,  and  Lower  Coal  Measures  in  the  eastern  portion  of  the  State. 

In  eastern  Canada  the  Oriskany  sandstone  is  used. 

Production  of  Glass  Sand.  —  About  19  states  report  a  pro- 
duction of  glass  sand,  but  all  of  the  material  may  not  be  used  in 
glass  manufacture.  The  production  of  the  important  producers 
as  well  as  the  total  for  the  United  States  is  given  below:— 

QUANTITY  AND  VALUE  OF  GLASS  SAND  IN  UNITED  STATES,  1912-1914 


1912 

1913 

1914 

SHORT 
TONS 

VALUE 

SHORT 
TONS 

VALUE 

SHORT 
TONS 

VALUE 

California 

9,535 

$8,664 

i 

i 

! 

i 

Illinois 

323,467 

225,434 

350,229 

$239,277 

339,551 

$246,803 

Indiana    . 

26,040 

10,641 

1,842 

1,861 

36,977 

14,138 

Missouri  . 

129,030 

81,817 

130,676 

91,284 

160,190 

112,484 

Michigan 
New  Jersey 
New  York 

i 
102,782 

i 

79,027 
i 

2,938 
108,560 
35,514 

3,020 
82,577 
21,416 

26,035 
83,927 
i 

32,593 
62,595 
i 

Ohio    .     . 
Pennsylvania     . 
West  Virginia    . 

154,527 
427,936 

244,881 

164,462 
517,383 
287,038 

73,154 
513,867 
534,600 

65,892 
674,073 
668,214 

138,565 
512,718 
233,024 

131,766 
611,173 
269,602 

Total  United 

States    .     . 

$1,465,386 

$1,430,471 

1,791,800 

$1,895,991 

1,619,649 

$1,568,030 

1  Included  in  the  total. 

REFERENCES   ON   GLASS   SAND 

1.  Broadhead,    Mo.   Geol.   Surv.,    1872:    289,    1873.     (Mo.)     2.  Burchard, 
U.  S.  Geol.  Surv.,  Bull.  285:    459,  1906.     (Middle  Mississippi  Basin.) 

3.  Burchard,  Ibid.,  Bull.  285:    452,   1906.     (Glass  and  requirements.) 

4.  Burchard,  Ibid.,  Bull.  315:  361,  1907.     (Ind.,  Ky.,  O.)     4a.  Buttram, 
Okla.  Geol.  Surv.,  Bull.  10,  1913.     (Okla.)     5.  Calvin,  la.  Geol.  Surv., 
I:    24,   1893.     (la.)     6.  Campbell,  U.  S.   Geol.  Surv.,  Atl.  Fol.,  No. 
94:    49,    1903.     (Pa.)     6a.  Carney,    Denison   Univ.,    Sci.    Lab.,    Bull. 
XVI:   137,  1910.     (O.)     7.  De  Groot,  Calif.  State  Min.  Bur.,  9th  Ann. 
Kept.:    324,  1890,  also  Ibid.,  Bull.  38,  1906.     (Calif.)     8.  D'Invilliers, 
Sec.  Pa.  Geol.  Surv.,  F,  1878.     (Pa.)     9.  Grimsley,  First  Bien.  Kept. 
Kas.   Bur.   Labor,    1901-1902:    343,    1903.     (Kas.)     10.  Grimsley,  W. 
Va.  Geol.  Surv.,  IV:   375,  1909.     (W.  Va.)     11.  Kummel,  N.  J.  Geol. 
Surv.,  Kept,  for  1906:    77,  1907.      (N.  J.)     12.  Newland,  N.  Y.  State 
Mus.,  Bull.  93:    927,  1905.     (N.  Y.)     13.  Randolph,  Eng.  and  Min. 
Jour.,  Dec.  28,  1907.     (Silica  sand  industry.)     14.  Frink,  Amer.  Ceramic 
Soc.,  Trans.,  XI:  296,  1909.     (Properties  of  glass  sands.) 


CHAPTER  XI 


MINOR  MINERALS  — GRAPHITE  MONAZITE 
GRAPHITE 

Properties  and  Occurrence.  —  Graphite,  or  black  lead,  as  it  is  often 
termed  popularly,  is  a  form  of  carbon,  of  which  two  varieties  are 
generally  recognized,  especially  in  the  trade.  The  first  of  these, 
the  crystalline,  has  a  lamellar  or  flaky  structure,  and  is  of  high 
purity,  while  the  other  form,  which  is  classed  as  amorphous,  lacks 
crystalline  structure,  and  may  be  quite  impure.  However,  even 
the  purest  graphite  may  contain  at  least  a  few  tenths  per  cent  ash 
and  volatile  matter,  and  commercial  graphite  often  contains  an 
appreciable  content  of  impurities.  Those  containing  90-95  per 
cent  graphitic  carbon  meet  the  requirements  of  the  general  trade, 
but  for  many  purposes,  especially  paint-making,  graphites  with  as 
low  as  30  to  35  per  cent  graphitic  carbon  can  be  employed. 

The  following  analyses  of  graphite  from  a  number  of  localities 
(6)  show  the  variation  in  its  composition,  but  probably  do  not  in  all 
cases  represent  commercial  samples. 

ANALYSES  OF  GRAPHITE 


LOCALITIES 

SP.  GRAV. 

VOLATILE 
MATTER 

CARBON 

ASH 

Cumberland,  first  quality     .... 
Passau,  Bavaria      

2.3455 
2.3032 

1.10 
7.30 

91.55 

81.08 

7.35 
11.62 

Passau,  Bavaria      ...          ... 

2.3108 

4.20 

73.65 

22.15 

Mugrau  Bohemia 

2  1197 

4.10 

91.05 

4.85 

Ceylon  crystals   ...     .     .     .     .     . 
Ceylon,  commercial  quality  .... 
Gulf  of  Spencera,  S.  Australia    .     .     . 
Gulf  of  Spencera,  S.  Australia    .     .     . 

2.3501 
2.2659 
2.3701 
2.2852 
2.2863 

5.10 
5.20 
2.15 
3.00 
1.82 

79.40 
68.30 
25.75 
50.80 

78.48 

15.50 
26.50 
72.10 
46.20 
19.17 

Madagascar    

2.4085 

5.18 

70.69 

24.13 

Pissic,  Dep.  Hautes  Alpes     .... 
Ural  Mts    Russia 

2.4572 
2  1795 

3.20 
72 

59.67 
94.03 

37.13 
5.25 

Ticonderoga,  N.Y.,  vein  graphite    .     . 

2.2647 

.818 

97.422 

1.76 

344 


MINOR  MINERALS  345 

Graphite  is  usually  easily  recognized  by  its  peculiar  physical 
properties,  such  as  extreme  softness,  steel-gray  to  blue-black  color, 
greasy  feel  and  black  streak.  The  specific  gravity  is  2.20  to  2.27. 
The  luster  is  metallic  in  the  leafy  form,  but  earthy  when  the 
graphite  is  in  a  finely  divided  state.  In  such  event  it  may  be 
difficult  to  tell  it  from  amorphous  carbon,  although  graphite  can 
be  told  by  its  property  of  forming  graphitic  acid,  when  treated 
with  nitric  acid.  Molybdenite  is  the  only  mineral  with  which  it 
might  be  confused,  but  this  has  a  bluish  or  greenish  tinge  and  a 
greenish  streak. 

Mode  of  Occurrence.  —  Graphite  always  occurs  in  eruptive 
or  metamorphosed  rocks,  especially  the  latter.  The  different 
occurrences  include  schist,  gneiss,  quartzite,  crystalline  lime- 
stones, granulite,  syenite,  etc. 

The  shape  of  the  deposit  is  also  varied.  Thus  the  graphite 
may  form:  (1)  disseminations  in  metamorphic  rocks;  (2)  pockets 
in  metamorphic  or  in  igneous  rocks;  (3)  veins;  and  (4)  bedded 
deposits. 

The  gangue  minerals  are  important,  since  they  affect  the  process 
of  separation,  and  are  in  general  those  common  to  the  c  untry 
rock,  except  in  the  case  of  veins,  when  they  may  be  different. 
Mica  and  chlorite  are  undesirable,  as  they  are  hard  to  separate. 
Both  quartz  and  calcite  may  be  common  gangue  minerals,  and 
the  less  abundant  may  include  rutile,  titanite,  apatite,  etc. 

Genetic  Occurrence.  —  It  seems  probable  that  graphite  may 
be  of  either  igneous  or  sedimentary  origin,  although  the  latter  is 
possibly  the  more  important.  The  following  cases  are  recognized: 

1.  In  Igneous  Rocks. — There  is  no  doubt  that  graphite  may 
form  an  original  constituent  of  rocks  formed  by  the  cooling  and 
crystallization  of  a  magma.     For  examples  of  this  we  may  refer 
to  the  occurrence  of  graphite  in  meteorites,  in  the  native  iron  of 
Greenland,  in  the  nepheline  syenite  of  Siberia,  or  in  pegmatite 
dikes. 

Of  course,  where  the  intrusive  rock  has  pierced  sedimentary 
ones,  there  is  always  the  doubt  or  possibility  that  the  graphite 
may  have  been  derived  from  these.  This  fact  thas  been  pointed 
out  in  the  case  of  a  graphite-bearing  pegmatite  from  Maine,1 
and  another  from  New  Jersey.2 

2.  In  Veins.  —  This  manner  of  graphite  occurrence  affords  a 

1  Smith,  U.  S.  G.  S.,  Bull.  285:  280,  1906. 

2  Spencer,  U.  S.  G.  S.,  Geol.  Atl.  Fol.  161,  1908. 


346  ECONOMIC   GEOLOGY 

puzzling  problem.  The  veins  appear  to  represent  fissure  filling, 
and  may  be  several  feet  in  width.  They  are  found  not  only  in 
igneous  rocks  such  as  granites  and  pegmatites,  but  also  in  meta- 
morphosed sediments,  and  while  they  were  probably  formed  at 
considerable  depths,  it  has  been  suggested  that  in  some  cases  at 
least,  the  temperature  did  not  exceed  575°  C.1 

Some  believe  that  the  graphite  was  derived  from  surrounding 
sediments,  and  deposited  shortly  after  the  pegmatitic  injection. 
Others  hold  the  view  that  the  graphite  has  been  derived  from 
gaseous  constituents  of  the  magma,  it  being  pointed  out  that  if 
CO  and  H  are  present,  they  will  react  below  500°  C.  according  to 
the  equation 

2CO+2H2<=±2C+2H2O. 

This  may  be  the  origin  of  the  graphite  in  the  veins  of  Ceylon, 
Montana  and  New  York. 

3.  In  Metamorphic  Rocks.  —  These  may  include  regionally  and 
and  contact  metamorphosed  rocks.  It  is  quite  generally  admitted 
that  the  carbonaceous  matter  of  sedimentary  rocks  may  undergo 
a  recrystallization  during  metamorphism  resulting  in  the  forma- 
tion of  graphite. 

Where  graphite  has  been  produced  by  contact  metamorphism, 
some  writers  (Weinschenk)  have  sought  to  show  that  it  represents 
exhalations  from  the  magma,  but  this  hardly  seems  necessary, 
especially  when  we  find  that  the  metamorphosed  formation,  if 
traced  away  from  the  eruptive,  is  carbonaceous. 

The  intrusion  of  igneous  rocks  into  or  near  coal  appears  in 
some  cases  to  have  produced  crystalline  (l,  p.  41),  in  other  instances 
amorphous  graphite.2  As  an  example  of  the  latter  we  may 
refer  to  deposits  in  central  Sonora,  Mexico,  where  coal  beds  up 
to  24  feet  in  thickness,  enclosed  in  sandstone,  have  been  meta- 
morphosed by  granite. 

Distribution  of  Graphite  in  the  United  States.  —  Crystalline 
graphite  is  widely  distributed  in  the  United  States,  occurring  in 
contact  zones  between  igneous  and  sedimentary  rocks,  in  meta- 
morphic  rocks,  etc.,  but  the  known  deposits  of  commercial  value 
are  few  in  number. 

Most  of  the  domestic  supply  has  been  obtained  from  New  York 
State. 

New  York  (4,  11,  lla,  12).  —  The  producing  mines  are  located  on 

1  Bastin,  Econ.  Geol.  V:  152,  1910.        2  Bastin,  U.  S.  Geol.  Surv.,  Min.  Res.  1908. 


MINOR  MINERALS 


347 


FIG.  114. — Map  showing  principal  graphite  mines  of  northeastern  states. 
1.  Crown  Point  Graphite  Co.;  2.  Ticonderoga  mine;  3.  Dixon's  American 
Mine;  4.  Hague  mine;  5.  Rowland  Graphite  Co.;  6.  Champlain,  and  Adiron- 
dack Graphite  Companies;  7.  Sacandaga  Graphite  Co.;  8.  Empire  Graphite 
Co.;  9.  Saratoga  Graphite  Co. ;  10.  Macomb  Graphite  Co.;  11.  Bloomingdale 
Mine;  12.  Raritan  Graphite  Mine,  High  Bridge;  13.  Eynon  Graphite  Co., 
Coventry ville;  14.  Girard  Graphite  Co.,  Rock  Graphite  Mining  Co.,  Crucible 
Flake  Graphite  Co.;  15.  Anselma  Mine,  Federal  Carbon  Mine,  Chester  Mine; 
16.  Acme,  Pennsylvania  and  Pettinos  Bros.'  Mine;  17.  Boyertown  Mine; 
18.  Penn  Mine,  Mertztown;  19.  Backenstoe  Mine;  20.  Sturbiidge  Mine. 
(U.  S.  GeoL  Surv.,  Min.  Res.  1913.) 


348  ECONOMIC   GEOLOGY 

the  southeastern  side  of  the  Adirondacks  in  Essex,  Warren,  Wash- 
ington, and  Saratoga  counties,  and  the  state  leads  all  others  in  its 
production  of  graphite,  partly  because  of  the  steady  production  of 
one  large  mine. 

The  graphite  occurs  in  the  following  ways :  1 .  In  pegmatite  veins, 
forming  bunches,  associated  chiefly  with  quartz,  but  also  feldspar, 
pyroxene,  hornblende,  mica,  calcite,  scapolite,  apatite,  sphene,  etc. 
This  type  of  deposit  is  of  little  commercial  value.  2.  Veinlets  of 
graphite  with  quartz  in  gneiss.  3.  Graphitic  quartzites,  represent- 
ing metamorphosed  pre-Cambrian  sediments.  These  are  the  most 
important  type.  4.  Graphitic  disseminations  in  Algonkian  lime- 
stones. 

At  the  American  Graphite  Company's  mine,  which  is  represen- 
tative of  3,  the  material  worked  is  a  medium-grained,  quartz- 
graphite  schist,  which  averages  6.25  per  cent  graphitic  carbon. 
The  associated  minerals  are  quartz,  mica,  and  apatite.  The  graph- 
ite rock  varies  from  3-20  feet  in  thickness,  and  is  overlain  by 
garnet  gneiss. 

Rhode  Island  (5).  —  Amorphous  graphite,  graphitic  anthracite,  or 
graphitic  shale,  as  it  has  been  variously  called,  has  been  known  for 
many  years  to  occur  in  the  metamorphosed  Carboniferous  rocks 
near  Providence  and  Tiverton,  Rhode  Island,  but  the  production 
has  been  irregular.  At  the  Cranston  Mines  near  Providence,  which 
are  the  largest,  the  section  shows  a  series  of  interbedded,  sandy, 
carbonaceous,  and  graphitic  shales,  something  over  300  feet  thick, 
all  folded  and  perhaps  faulted.  The  main  graphitic  bed  is  30  feet 
thick. 

The  following  analyses  represent  the  range  of  composition  01 
the  material: — 

Moisture  ^atile  F^  ^ 

1.  13.26  2.56  65.30  18.88 

2.  23.68  3.01  42.54  30.77 

Ashley  has  characterized  the  material  as  a  high-ash,  high- 
moisture,  graphitic  anthracite  coal  of  high  specific  gravity 
(1.65-2.45),  which  cannot  be  used  successfully  as  a  fuel,  unless  it 
can  be  mined  and  delivered  at  the  furnace  in  Providence  or  Boston 
for  less  than  one-half  the  wholesale  price  of  competing  coals. 

The  material  is  used  chiefly  for  paint  and  foundry  facings. 

Pennsylvania  (8) .  —  Crystalline  graphite  has  been  mined  at  several  local- 
ties  in  eastern  Pennsylvania,  where  it  occurs  in  crystalline  rocks. 


MINOR  MINERALS  349 

Alabama  (14).  —  Crystalline  graphite  is  found  in  granites  and  schists  in 
Clay,  Chilton,  and  Coosa  counties.  In  Clay  County,  for  example,  the  graph- 
ite is  uniformly  disseminated  throughout  a  zone  of  mica-free  weathered 
granite,  ten  miles  long  and  several  hundred  feet  wide.  Its  depth  has  been 
proven  to  75  feet,  with  an  average  of  4.5  per  cent  graphite.  A  graphitic 
clay  found  in  the  slightly  crystalline  schists  of  the  Palaeozoic  area  of  Clay 
and  Tallapoosa  counties  is  used  as  a  lubricant. 

New  Mexico  (10).  — Amorphous  graphite  is  known  to  occur  in  the  canon 
of  the  Canadian  River,  about  7  miles  southwest  of  Raton.  The  bed,  which 
is  nearly  horizontal,  has  been  traced  laterally  into  the  principal  bituminous 
coal  seam  of  the  Raton  field,  and  that  portion  which  is  graphitized  owes  its 
character  to  diabase  intrusions,  the  change  being  most  complete  where  the 
bed  was  fractured  and  the  diabase  forced  into  it.  The  graphite  is  said  to 
occur  in  pockets  or  irregular  masses  in  the  diabase,  and  is  columnar  normal 
to  the  faces  of  the  igneous  rock.  It  has  been  mined  somewhat  and  sold  for 
the  manufacture  of  mineral  paint. 

Montana  (20).  —  Near  Dillon,  Mont.,  there  is  a  deposit  somewhat  similar 
to  those  of  Ceylon,  for  the  graphite  occurs  in  veins.  These  may  be  irregular, 
forming  a  network,  or  some  of  the  narrow  ones  appear  persistent.  They 
occur  in  schists  and  crystalline  limestones,  which  have  been  penetrated 
by  pegmatite.  The  graphite  is  said  to  be  softer  than  the  Ceylon  product. 

Other  States.  —  Developments  of  graphite  have  been  made  in  other 
states,  such  as  Michigan,  Wisconsin,  Virginia  (17),  Wyoming  (2),  Maine 
(15),  Georgia  (9),  etc.,  but  the  output  is  not  steady. 

Canada  (l,  6).  —  Mining  for  graphite  in  Canada  began  in 
1847,  and  has  continued  since,  the  production  coming  from  rocks 
of  the  Hastings-Grenville  series  of  eastern  Ontario  and  the 
adjoining  portions  of  Quebec.  The  1913  production  came  from 
the  Buckingham  district,  Quebec  and  Calabogie  and  Wilberforce, 
Ont.  Canadian  graphite  occurs  in  the  following  three  ways: 
(1)  As  disseminations  in  gneiss,  quartzite  or  schist,  the  beds 
being  sometimes  more  highly  graphitic,  where  pierced  by  intru- 
sives;  (2)  As  usually  narrow  or  irregular  veins,  in  or  near  igneous 
rocks;  (3)  As  veins  or  irregular  masses  in  limestone  near  igneous 
rocks;  (4)  As  a  constituent  of  pegmatite  veins  cutting  the 
Grenville  series. 

Only  the  first  of  these  is  of  much  economic  importance. 

Other  Foreign  Deposits.  —  Ceylon  (1,  3)  is  the  leading  graphite-pro- 
ducing country  of  the  world,  the  chief  mines  being  located_in  the  mountainous 
area  of  the  southwestern  and  south  central  part  of  the  island.  The  chief 
rocks  are  gneisses  with  some  interbedded  dolomites,  and  some  intrusives, 
especially  granite  pegmatites.  While  some  disseminated  graphite  is  found 
in  gneiss  and  limestone,  the  commercially  important  deposits  are  veins  of 
irregular  width,  occurring  along  fracture  planes.  In  small  veins  the  graphite 


350 


ECONOMIC  GEOLOGY 


forms  an  aggregate  of  parallel  needles  at  right  angles  to  the  wall,  but  in 
the  larger  veins  a  coarse  platy  structure  is  observed.  Pyrite  and  quartz 
are  not  uncommon,  while  biotite,  orthoclase,  pyroxene,  apatite,  allanite, 
and  rutile  are  more  rare. 

Bavaria  (1)  is  another  important  producer.  There,  in  the  Passau  district 
(Fig.  115),  the  country  rock  is  cordierite  gneiss,  surrounded  by  granite,  and 
containing  bands  of  schist,  and  limestone,  as  also  some  intrusive  rocks. 


FIG.  115.  —  Geologic  map  of  Passau,  Bavaria,  graphite  district. 
De  Launay,  from  Stutzer,  Die  Nicht-Erze.) 


(After  Gumbel- 


The  graphite  forms  lenses  conformable  with  the  gneiss  and  schist,  with  often 
a  foot  wall  of  limestone  and  syenite,  and  a  hanging  wall  of  granite.  Both 
the  country  gneiss  and  graphite  are  strongly  decomposed.  Weinschenk 
advanced  the  theory  that  the  graphite  was  deposited  by  exhalations  from 
the  granite,  and  that  the  kaolinization  was  due  to  the  same  cause.  The 
first  is  disputed  by  some,  who  consider  the  carbon  to  be  original  in  the 
rock,  while  the  latter  is  very  unlikely,  the  kaolin  being  an  ordinary  product 
of  weathering. 

Austria  is  the  largest  producer  in  Europe,  the  deposits  of  southern  Bo- 
hemia being  similar  to  those  of  Bavaria.     The  Styrian  ones  form  thin  beds 


MINOR  MINERALS  351 

in  schist,  and  those  of  Mahren  occur  in  crystalline  limestone  which  is  inter- 
bedded  with  schists,  gneisses  and  quartzites.  The  Madagascar  l  deposits 
of  crystalline  graphite,  and  Ko:ea 2  deposits  of  amorphous  graphite  are 
also  important. 

Uses.  —  On  account  of  its  refractoriness  and  high  heat  con- 
ductivity, graphite  is  employed  in  the  manufacture  of  crucibles 
for  use  in  the  steel,  brass,  and  bronze  industries.  For  making 
these  it  is  mixed  with  clay  and  some  sand.  Ceylon  graphite  is 
specially  suitable  for  this  class  of  work,  because  of  its  peculiar 
fibrous  structure,  but  small  amounts  of  American  and  Madagascar 
graphite  are  also  used.  Amorphous  graphite  has  not  given 
success  in  crucible  work.  In  addition  graphite  is  employed  for 
making  stove  polish,  foundry  facings,  paint,  lead  pencils,  lubricat- 
ing powder,  glazing,  electrotyping,  steam  piping,  for  adulterating 
fertilizers,  coloring  and  glazing  coffee  beans  or  tea  leaves, 
etc. 

The  use  of  graphite  for  paint  has  increased  greatly  in  the  last 
few  years,  the  material  employed  being  chiefly  of  the  amorphous 
variety  and  rather  impure.  Another  recent  and  increasing  use 
of  amorphous  graphite  and  of  fine  flake  graphite  is  for  boiler  com- 
pound. 

Both  amorphous  and  crystalline  graphite  can  be  used  for  lubri- 
cating purposes.  The  use  of  graphite  for  pencil  manufacture, 
though  an  early  one,  and  perhaps  the  best  known,  consumes  but 
a  small  percentage  (under  10  probably)  of  the  world's  supply. 
For  this  purpose  amorphous  graphite  is  demanded,  and  while 
Bohemian  and  Bavarian  graphite  were  originally  used,  Sonora, 
Mexico,  now  supplies  American  manufacturers  with  all  they 
need. 

Graphite  is  also  made  artificially  from  anthracite  coal,  but  its 
introduction  has  not  seriously  affected  the  market  for  the  natural 
product. 

Crystalline  graphite  is  put  through  a  concentrating  process  be- 
fore shipment  to  market.  This  is  necessary  in  order  to  free  it  from 
the  associated  minerals.  Both  wet  and  dry  methods  of  separation 
are  employed,  while  more  recently  air  separation  has  been  tried 
with  some  success. 

Graphite  Industry.  —  In  spite  of  the  importance  of  graphite, 
the  United  States  does  not  produce  more  than  about  one-seventh 

1  IT.  S.  Geol.  Surv.,  Min.  Res.,  1913:  23,  1914. 

2  Ibid.,  p.  238. 


352 


ECONOMIC   GEOLOGY 


of  the  total  quantity  consumed  in  this  country.  This  unsatisfactory 
condition  of  the  domestic  industry  is  due  to:  (1)  The  superiority 
of  the  Ceylon  product;  (2)  the  low  cost  of  production  of  the 
Ceylon  product;  and  (3)  the  fact  that  both  United  States  and 
Canadian  graphites  are  disseminated  and  hence  require  separation 
from  the  associated  minerals.  Considerable  Madagascar  graph- 
ite, which  is  of  the  flake  variety,  is  imported  into  the  United 
States.  It  is  cleaned  after  being  received  here.  Korean  amor- 
phous graphite  is  also  imported. 

Production  of  Graphite.  —  The  domestic  production  of  crys- 
talline graphite  does  not  form  more  than  a  small  proportion  of  the 
entire  consumption. 

In  1914  the  total  production  of  crystalline  graphite  came  from 
Alabama,  New  York,  Pennsylvania,  and  Montana.  The  Alabama 
production  amounted  to  2,410,200  pounds,  valued  at  $118,000, 
which  was  less  than  half  of  the  total  production  of  5,220,539 
pounds,  valued  at  $285,368.  Alabama  showed  a  slight  increase 
over  the  production  of  the  previous  years. 


PRODUCTION  OF  NATURAL  GRAPHITE  IN  THE  UNITED  STATES,  1910-1914 


YEAR 

AMORPHOUS 

CRYSTALLINE 

TOTAL 

SHORT  TONS 

VALUE 

POUNDS 

VALUE 

SHORT  TONS 

VALUE 

1910  . 
1911  .     . 
1912  .     . 
1913  .     . 
1914  .     . 

1,407 
1,223 
2,063 
2,243 
1,725 

$39,710 
32,415 
32,894 
39,428 
38,750 

5,590,592 
4,790,000 
3,543,771 
5,064,727 
5,220,539 

$295,733 
256,050 
187,689 
254,328 
285,368 

4,202 
3,618 
3,835 
4,775 
4,336 

$335,443 
288,465 
220,583 
293,756 
324,118 

IMPORTS  OF  GRAPHITE  AND  PRODUCTION  OF  ARTIFICIAL  GRAPHITE  IN  THE 
UNITED  STATES,  1910-1914 


iTFAR 

IMPORTS  OF  NATURAL 
GRAPHITE 

PRODUCTION  OF  ARTIFICIAL  GRAPHITE 

SHORT  TON^ 

VALUE 

POUNDS 

VALUE 

PRICE  PER 
POUND  (CT8.) 

1910     . 
1911     . 
1912     . 
1913     . 
1914     . 

25,235 
20,702 
25,643 
28,879 
22,002 

$1,872,592 
1,495,729 
1,709,337 
2,109,791 
1,398,261 

13,149,100 
10,144,000 
12,896,347 
13,633,342 
10,455,139 

$945,000 
664,000 
830,193 
973,397 
698,800 

7.20 
6.55 
6.44 

7.14 
6.68 

.The  world's  production  in  1911  is  given  on  page  353. 


MINOR   MINERALS 


353 


WORLD'S  PRODUCTION  OF  NATURAL  GRAPHITE  IN  1912 


COUNTRY 

SHORT  TONS 

VALUE 

COUNTRY 

SHORT  TONS 

VALUE 

United  States    . 

2,694 

$211,883 

Italy  .... 

14,517 

$      77,236 

Canada 

2,059 

117,117 

Japan.      .      .      . 

163 

10,935 

Mexico           .      . 

3,158 

96,668 

Chosen  (Korea) 

82,108 

Germany 

13,814 

81,514 

India  (1911  prod.) 

4,533 

45,867 

Austria 

50,017 

378,867 

Ceylon     . 

ise.eeo 

12,  707,973 

Norway 

285 

1,898 

Madagascar 

3,011 

239,291 

Sweden 

87 

2,535 

South  Africa     . 

42 

5,621 

France 

661 

1,635 

1  Export  figures. 
PRODUCTION  OF  GRAPHITE  IN  CANADA,  1912-1914,  IN  SHORT  TONS 


YEAR 

QUANTITY 

VALUE 

1912 
1913 
1914 

2060 
2162 
1647 

$117,122 
90,282 
107,203 

REFERENCES    ON    GRAPHITE 

1.  Stutzer,  Die  Nicht-Erze,  Berlin,  1911.  2.  Ball,  U.  S.  Geol.  Surv.,  Bull. 
315:  426.  (Wyo.)  3.  Bastin,  Econ.  Geol.,  VII:  419,1912.  (Ceylon.) 
4.  Bastin,  Econ.  Geol.,  V:  134,  1910.  (N.  Y.)  4a.  Bastin,  U.  S. 
Geol.  Surv.,  Min.  Res.,  1914:  164,  1915.  (Calif.)  5.  Ashley,  U.  S. 
Geol.  Surv.,  Bull.,  615,  1915.  (R.  I.)  5a.  Brummell,  Can.  Min. 
Jour.,  XXVIII:  163,  1907.  (Can.)  6.  Cirkel,  Kept,  on  Graphite, 
Dept.  Inter.  Can.,  Mines  Branch,  1907.  (General.)  7.  Downs,  Iron 
Age,  April  19  to  June  14,  1900.  (General  on  uses  and  technology.) 
7a.  Haenig,  Brass  World,  VII:  307,  1911.  (Use  for  crucibles.)  76, 
Hess,  Eng.  Mag.,  XXXVIII:  36,  1909.  (Sonora,  Mex.)  8,  Miller, 
Top.  and  Geol.  Com.  Pa.,  Bull.  6,  1912.  9.  Hayes  and  Phalen,  U.  S. 
Geol.  Surv.,  Bull.  340:  463.  (Ga.)  10.  Lee,  U.  S.  Geol.  Surv., 
Bull.  530:  371,  1913.  (N.  Mex.)  11.  Kemp  and  Newland,  N.  Y. 
State  Mus.,  51st  Ann.  Kept.,  II:  539.  (N.  Y.)  lla.  Kemp,  Science, 
n.  s.,  XII:  81,  1900.  (Origin.)  12.  Ogilvie,  N.  Y.  State  Mus.,  Bull. 
96, 1905.  (N.  Y.)  13.  Rowe,  Min.  Wld.,  XXVIII :  839, 1908.  (Mont.) 
14.  Smith,  E.  A.,  Min.  Indus.,  XVI:  567.  (Ala.)  15.  Smith,  G.  O., 
U.  S.  Geol.  Surv.,  Bull.  285:  480,  1905.  (Me.)  16.  Smith,  P.  S., 
U.  S.  Geol.  Surv.,  Bull.  345:  250,  1907.  (Alaska.)  17.  Watson, 
Min.  Res.  Va.,  1907:  188.  (Va.)  18.  Weinschcnk,  Zur  Kenntniss 
der  Graphitlagerstatten,  Munich,  1897.  (Origin.)  19.  Weinschenk 
Zeitschr.  f.  Kryst.  u.  Min.,  XXVII:  135,  1897.  (Passau  district.) 
20,  Winchell,  Econ,  Geol.,  VI:  218,  1911,  (Mont,) 


354  ECONOMIC   GEOLOGY 


LITHIUM 

The  two  minerals  most  commonly  used  as  a  source  of  lithium  are 
Lepidolite  (KLi[Al(OH,F2)]Al(SiO3)3)  and  Spodumene  (LiO2,  A12O3, 
4  SiO2).  The  largest  deposits  of  lepidolite  at  present  known  in  the 
United  States  are  found  near  Pala,  California.  Spodumene  occurs 
in  some  quantities  in  the  Black  Hills  of  South  Dakota  and  in  Con- 
necticut and  Massachusetts,  but  none  of  these  occurrences  have 
yet  been  worked  to  supply  lithium. 

In  the  last  few  years  there  has  been  a  great  demand  for  lithium 
minerals  for  use  in  the  manufacture  of  lithium  carbonate.  Since 
most  of  this  substance  now  in  use  is  made  in  Germany,  nearly  all  the 
American  mineral  has  been  shipped  to  that  country.  The  American 
supply  of  carbonate  is  imported  from  Germany,  selling  in  New  York 
for  $4.20  a  pound.  The  chief  use  of  lithium  salts  is  in  the  preparation 
of  mineral  waters. 

The  production  of  lithium  minerals  in  the  United  States  is 
very  irregular  and  small. 


LITHOGRAPHIC  STONE 

Properties.  —  Lithographic  stone  (1,  3)  is  a  very  fine-grained, 
homogeneous  limestone,  used  for  lithographic  purposes.  It  may 
be  either  pure  lime  carbonate  or  magnesian  limestone,  but  so  far  as 
known  this  difference  in  composition  exerts  no  important  influence 
on  its  physical  character.  The  two  following  analyses  will  serve  to 
indicate  this  difference  in  composition,  No.  1  being  the  standard 
Bavarian  stone  and  No.  2  the  Brandenburg,  Kentucky,  rock :  — 

INSOLUBLE  IN  HC1  SOLUBLE  IN  HC1 

SiO2   (AlFe)2Os  CaO     A12O3     FeO       MgO        CaO       Na2O  K2O    Moist.    H2O       CO2 

1.  1.15  .22  Trace  .23   .26   .56  53.80    .07~   .23   .69  42.69 

2.  3.15  .45   ,09   .13   .31   6.75  44.76    .13    .41   .47  43.06 

The  physical  character  of  the  stone  is  of  prime  importance,  for  in 
order  to  yield  the  best  results  it  should  be  fine-grained,  homogene- 
ous, free  from  veins  or  cracks,  of  just  sufficient  porosity  to  absorb  the 
grease  holding  the  ink,  and  soft  enough  to  permit  its  being  carved 
with  the  engraver's  tool.  Owing  to  these  strict  requirements  but 
few  localities  have  produced  good  stone. 


MIXOR   MINERALS  355 

Sources  of  Supply.  —  Lithographic  stone  is  not  confined  to  any 
one  geologic  formation,  and  deposits  have  been  reported  from  many 
states  both  east  and  west.  Some  of  these  appear  to  be  of  inferior 
quality,  while  others  are  too  far  from  railroads.  The  most  prom- 
ising developed  deposit  is  that  found  at  Brandenburg,  Kentucky 
(2,  6),  at  which  locality  a  bed  of  blue-gray  stone  three  feet  thick  is 
quarried  and  used  by  some  establishments  in  the  south  and  south- 
west. Another  bed  of  good  quality  has  also  been  described  from 
Iowa  (1). 

The  main  source  of  the  world's  supply  is  obtained  from  the  Jurassic 
limestone  of  the  Solenhofen  district  in  Bavaria  (4),  in  which  the  quarries 
have  been  worked  for  a  number  of  years,  but  the  supply  is  said  to  be 
becoming  unsatisfactory  and  unreliable.  The  stones  are  trimmed  at  the 
quarries,  and  sizes  of  22  or  28  by  40  inches  are  in  the  greatest  demand. 
From  these  they  range  up  to  sizes  40  by  60  inches.  The  best  quality  stones 
sell  for  22  cents  per  pound. 

The  domestic  demand  is  not  large,  and  it  is  probable  that  one  or 
two  well-developed  and  well-managed  native  quarries  could  no 
doubt  satisfy  it. 

The  successful  substitution  of  zinc  or  aluminum  plates  for  certain 
classes  of  lithographic  work  is  said  to  have  had  a  noticeable  in- 
fluence on  the  demand  for  lithographic  stone.  Onyx  has  also,  in 
some  cases,  been  found  to  make  a  good  substitute. 

REFERENCES  ON  LITHOGRAPHIC  STONES 

1.  Hoen,  la.  Geol.  Surv.,  XIII  :  339,  1902.     (la.,  also  general.)    2.  Kiibel, 
Eng.   and  Min.  Jour.,  LXXII  :  668,  1901.     (Ky.)     3.  Kiibel,  Min. 
Resources,  U.  S.  Geol.  Surv.,  1900  :  869,  1901.     (Excellent  general 
article.)      4.  Dammer    und    Tietze,    Nutzbaren    Mineralien,    I:     412, 
1913.     (Europe.)     5.  Mo.    Geol.    Surv.,    Bull.    3:     38,    1890.     (Mo.) 
6.  Ulrich,  Eng.  and  Min.  Jour.,  LXXIII:  895,  1902.     (Ky.) 


MAGNESITE 

Properties  and  Occurrence.  —  This  mineral,  which  is  a  car- 
bonate of  magnesium  with  47.6  per  cent  magnesia  (MgO),  has  a 
hardness  of  3.5  to  4.5  and  a  specific  gravity  of  3  to  3.12. 

It  commonly  occurs  in  veins  or  in  masses  replacing  other  rocks 
rich  in  magnesia,  such  as  serpentines,  talcose  schists,  dolomites, 
etc.  Its  color  is  white  or  yellowish,  and  when  massive  it  some- 
times resembles  unglazed  porcelain,  and  is  quite  brittle,  but  when 
crystalline  it  resembles  coarse-grained  metamorphosed  limestone. 


356  ECONOMIC  GEOLOGY 

Magnesite  occurrences  may  be  grouped  into  two  classes,  viz.: 
the  dolomite  and  the  serpentine  type. 

Dolomite  Type  (4)  .  •  —  The  only  important  occurrence  of  this 
type  is  in  a  belt  in  Austro-Hungary,  the  mcst  important  district 
being  near  Veitsch  in  Styria.  The  material,  which  is  coarsely 
crystalline,  occurs  as  replacements  of  Carboniferous  dolomite, 
and  may  not  only  contain  an  admixture  of  siderite,  or  even  scat- 
tered metallic  sulphides,  but  also  veinlets  of  dolomite  and  some- 
times talc.  These  deposits  form  the  main  source  of  the  world's 
supply. 

An  impure  magnesi+e  containing  considerable  dolomite  is 
known  in  Quebec,  and  a  deposit  of  hydromagnesite  at  Atlin,  B.  C. 

Serpentine  Type  (l,  3,  4).  —  This  type  forms  veins  (PL  XXXV, 
Fig.  2),  or  lenses  in  serpentine,  and  has  been  derived  from  the 
latter,  or  possibly  even  from  the  minerals  that  altered  to  serpen- 
tine, probably  by  the  action  of  surface  waters.  The  following 
equations  will  illustrate  this  change  : 


or 
3Mg3FeSi208+3C02+4H20+0 


The  silica  formed  above  may  be  deposited  with  the  magnesite, 
or  in  separate  veins  as  opal  or  chalcedony. 

Other  impurities  in  the  magnesite  may  be  iron,  alumina  and 
lime. 

In  texture  the  serpentine  magnesite  is  fine  grained,  dense  or 
massive,  and  when  pure,  white  in  color. 

Although  this  type  is  of  almost  world-wide  distribution,  the 
most  important  deposits  are  on  the  Island  of  Eubcea,  Greece, 
where  some  of  the  lenses  are  50  feet  thick  and  75  to  100  feet 
long  (4). 

Small  ones  are  known  in  Pennsylvania  and  Maryland,  but  are 
not  worked,  as  they  cannot  compete  with  the  imported  magnesite. 

California  (l).  —  Deposits  of  magnesite  (Fig.  116)  are  scattered 
along  the  Coast  Range  from  Mendocino  County  at  least  to  a  point 
south  of  Los  Angeles,  and  along  the  western  slope  of  the  Sierra 
Nevada  from  Placer  County  to  Kern  County.  The  greatest  pro- 
duction comes  from  near  Porterville  in  Tulare  County  (Fig.  116). 


PLATE  XXXV 


FIG.  1.  —  Magnosite  mine  near  Winchester,  Calif.     (H.  Ries,  photo.) 


FIG.  2.  —  Network  of  magnesite  veins  in  Serpentine,  same  mine.    (H.  Ries,  photo.) 

(357) 


358 


ECONOMIC  GEOLOGY 


The  deposits  all  occur  as  veins  in  serpentine,  the  larger  number 
being  in  the  Coast  Range. 


FIG.  116.  —  Map  of  part  of  California  showing  distribution  of  magnesite  deposits. 
(After  Yale  and  Gale,  U.  S.  GeoL  Sure.,  Min.  Res.  1913.) 

The  much-fractured  and  faulted  serpentines  of  the  Coast 
Ranges,  which  are  probably  of  Lower  Cretaceous  age,  appear 
to  have  been  derived  from  olivine-pyroxene  rocks,  and  the  magne- 
site may  have  been  formed  from  both  the  serpentine-making 


MINOR  MINERALS 


359 


minerals  and  the  serpentine  itself.  In  some  cases  the  magnesite 
forms  a  network  of  veins  in  the  serpentine,  but  since  its  origin 
is  due  to  the  action  of  surface  waters,  the  deposits  may  be  of 


FIG.  117.  —  Plan  of  magnesite  veins  and  workings  4  miles  northeast  of  Porter- 
ville,  Calif.       (After  Hess,  U.  S.  Geol.  Surv.>  Bull.  355.) 


limited  depth.     As  the  magnesite  weathers  less  readily  than  the 
serpentine,  the  vein  outcrops  often  stand  out  in  bold  relief. 

The  following  analyses  show  the  composition  of  the  magnesite 
from  several  localities:  — 

ANALYSES  OF  MAGNESITE 


1 

2 

3 

4 

5 

SiO2        

7.67 

.73 

2.28 

1.67 

2.24 

A12O3      
Fe2O3      

.26 
.29 

.14 
.21 

.03 
.26 

3.47 

4.68 

2.05 

CaO        

.04 

.40 

1.32 

2.94 

2.48 

MgO       ..... 

4342 

46.61 

45.17 

86.90 

93.63 

CO2 

4808 

51  52 

50.74 

99.76 

99.61 

99.80 

99.66 

100.40 

Siliceous  Magnesite,  8  m.  north  of  Cazadero,  Sonoma  County.  2.  Ala- 
meda  claim,  Santa  Clara  County.  3.  Four  miles  northeast  of  Porter- 
ville,  Tulare  County.  Too  high  in  lime  for  good  cement.  Used  in 
wood-pulp  whitening.  4.  Calcined  magnesite,  Nyustya,  Hungary. 
5.  Calcined  magnesite,  Greece.  1-5  from  Ref.  1. 


360 


ECONOMIC  GEOLOGY 


Uses.  —  Crude  magnesite  is  used  chiefly  for  making  carbon 
dioxide,  but  its  application  for  this  purpose  is  decreasing. 

Caustic  magnesite  is  that  which  has  not  been  thoroughly 
calcined  and  contains  3  to  4  per  cent  carbon  dioxide.  This  is 
used  for  making  oxychloride  cement  (a  mixture  of  magnesia  and 
magnesium  chloride),  and  probably  over  90  per  cent  of  the  ser- 
pentine magnesite  is  employed  for  this  purpose.  The  caustic 
magnesite  deteriorates  on  exposure,  and  after  4  or  5  months  may 
have  taken  up  two  or  three  ^imes  as  much  carbon  dioxide  as  was 
left  in  it. 

Dead-burned  magnesite  has  less  than  1  per  cent  carbon  dioxide, 
and  does  not  take  up  any  from  the  air.  The  dolomite  variety  is 
used  almost  exclusively  for  this  purpose  and  goes  into  the  manu- 
facture of  refractory  bricks. 

Magnesite  is  used  as  a  toilet  preparation,  or  in  medicine,  and 
as  a  boiler  covering  when  mixed  with  asbestos. 

California  magnesite  has  been  used  in  the  paper-manufacturing 
industry,  after  conversion  into  bisulphite.  Epsom  salt,  while 
derived  chiefly  from  the  Stassfurt  salt  deposits,  is  also  manufac- 
tured from  magnesite. 

The  metal  magnesium  is  not  made  from  magnesite,  but  from 
magnesium  chloride  obtained  from  the  Stassfurt,  Germany,  and 
other  brines. 

The  domestic  production  is  obtained  entirely  from  California 
and  has  been  as  follows: — 

PRODUCTION  OF  MAGNESITE  IN  UNITED  STATES,  1912-1914 


YEAR 

QUANTITY 

VALUE 

1912           '              .*."..     . 

Short  tons 
10,512 

$84,096 

1913    

9,632 

77,056 

1914    .  '.  •     •     •     • 

PRODUCTION  OF  MAGNESITE  IN  CANADA,  1912-1914 


YEAR 

SHORT  TONS 

VALUE 

1912          

1714 

$9645 

1913                            

515 

3335 

1914 

358 

2240 

PLATE  XXXVI 


FIG.  1.  —  View  in  glass  sand  pit,  on  Severn  River,  Md.  —  The  tunnel  shows  posi- 
tion of  bed  of  glass  sand.  The  overlying  beds  carry  too  much  iron  oxide. 
(H.  Ries,  photo.) 


FIG.  2.  —  View  showing  sapphire  workings,  Yogo  Gulch,  Mont.      (Photo  by  J.  P. 
Rowe.)     The  cut  indicates  position  of  sapphire-bearing  dike. 

(361) 


362 


ECONOMIC  GEOLOGY 


IMPORTS,   FOR  CONSUMPTION,    OF   MAGNESITE   INTO   THE   UNITED   STATES 
FOR  CALENDAR  YEARS  1912-1914,  IN  POUNDS 


1912 

1913 

1914 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

Magnesia: 
Calcined,    medi- 

.      • 

cinal    . 

104.106 

$     16,326 

54,915 

$    10,034 

159,547  !  $     19.342 

Carbonate     of, 

medicinal     . 

62,404 

2,812 

'70,823 

4,880 

46,183 

2.527 

Sulphate         of 

(Epsom  salts) 

10.703,209 

41,739 

8.121.677 

32.884 

13,826,899 

53.768 

Magnesite: 

Calcined,      not 

purified    .     . 
Crude  .     .     . 

250.503,372 
35.810,752 

1,265.339 
104,326 

334,187,404 
26,479,109 

1.672,565 

84,911 

243,633,205 
26,708,381 

1.323,194 
54,677 

IMPORTS   OF   MAGNESITE   CALCINED,    NOT   PURIFIED,    FOR   FISCAL   YEARS 
ENDING  JUNE  30,  1912-1914,  BY  COUNTRIES,  IN  SHORT  TONS 


COUNTRY 

1912 

1913 

1914 

Europe: 
Austria-Hungary    ..     .«  «  ' 

99,104 
25 

163,715 

134,260 

689 

2  412 

2  578 

114 

1  605 

3  23? 

CO 

Italy 

Netherlands        

2,410 

4,508 

4  191 

163 

United  Kingdom: 
England     

61 

1 

12 
1 

North  America: 

234 

350 

404 

Mexico 

81 

cy 

Total           ......... 

102,938 

172  591 

144  747 

REFERENCES    ON    MAGNESITE 

1.  Hess,  U.  S.  Geol.  Surv.,  Bull.  355,  1908.  (Calif.)  2.  Canaval,  Zeitschr. 
prak.  Geol.,  1912;  320.  (Tyrol.)  3.  Gale,  U.  S.  Geol.  Surv.,  Bull. 
540:  483,  1914.  (Calif.)  4.  Morganroth,  Amer.  Inst.  Min.  Engrs., 
Trans.  L:  890,1915.  (General.)  5.  Redlich,  Tscher.  min.  pet.  Mitth., 
XXVI:  499,  1907.  (Styria.)  6.  Dammer  and  LTietze,  Nutzbaren 
Mineralien,  I:  441,  1913. 


MEERSCHAUM 

Meerschaum  or  Sepiolite,  which  is  well  known  on  account  of  its 
use  for  making  pipes  and  other  smoker's  articles,  has  for  many 
years  been  obtained  mainly  from  Asia  Minor,  although  other  oc- 
currences are  known.  Deposits  of  promising  character  have 


MINOR  MINERALS 


363 


been  located  in  Grant  County,  New  Mexico,  and  although  not 
yet  commercially  developed,  deserve  mention. 

Sepiolite  has  a  probable  composition  of  H4Mg2Si3Oio,  and  when 
pure  is  a  white,  porous  mineral,  with  a  specific  gravity  of  about  2. 
It  absorbs  water  readily,  becoming  somewhat  plastic,  but  hardens 
again  on  drying.  It  has  a  hardness  of  2  to  2.5,  great  toughness,  and 
earthy  or  conchoidal  fracture,  the  toughness  being  most  pronounced 
in  those  forms  having  a  leathery  or  fibrous  texture.  Its  peculiar 
physical  properties  make  it  of  great  value  for  carving  into  pipes. 

In  New  Mexico  two  localities  are  known,  both  of  which  lie  in  the 
upper  Gila  River  valley,  at  points  located  respectively  23  miles 
east  of  north,  and  12  miles  northwest  of  Silver  City. 

At  the  Dorsey  mine,  northwest  of  Silver  City,  the  meerschaum 
occurs  as  veins,  lenses,  seams,  and  balls  in  a  limestone  of  probable 
Ordovician  age.  The  veins  are  filled  with  chert,  quartz,  calcite, 
clay,  and  meerschaum,  and  the  chert  which  is  the  most  important 
gangue  mineral,  occurs  in  the  veins  with  meerschaum  in  bands, 
lenses,  and  nodules. 

The  meerschaum  itself  occurs  either  as  irregular  nodules,  or  in 
massive  form.  Both  kinds  are  tough,  but  the  latter  is  finer  grained, 
less  leathery,  and  heavier. 

The  three  following  analyses  represent,  (1)  the  Dorsey  mine 
product;  (2)  the  theoretic  composition  of  meerschaum;  and  (3)  a 
material  from  another  deposit,  -which  resembles  the  true  meer- 
schaum, but  differs  from  it  in  its  high  alumina  content. 

ANALYSES  OF  MEERSCHAUM 


i 

2 

3 

SiO2     .     ...     .     .     .   V    4     .     . 

57.10 

60.8 

60.97 

AloOs  

58 

FeoOs  .... 

tr 

971 

MgO  

27.16 

27.1 

10.00 

CaO 

17 

22 

CO2 

32 

H2O     .... 

1478 

12  1 

19  14 

Total   .     .     .     .     .     .     .    .     .     . 

100.11 

100.0 

100.04 

The  deposit  cannot  as  yet  be  regarded  as  a  commercial  proposi- 
tion, but  may  become  so. 


364  ECONOMIC   GEOLOGY 

REFERENCES    ON    MEERSCHAUM 

1.  Collins,  Min.  Wld.,  XXVI:  688,  1907.  (N.  Mex.)  2.  Sterrett,  U.  S. 
Geol  Surv.,  Bull.  340:  1908.  (General  and  N.  Mex.)  3.  Dammer 
and  Tietze,  Nutzbaren  Mineralien,  II:  354,  1914. 


MICA 

Properties  and  Occurrence.  —  There  are  few  minerals  more 
widely  distributed  in  crystalline  rocks  than  mica,  and  yet  deposits 
of  economic  value  are  rare  because  the  mica  flakes  are  either  too 
small,  or  too  intimately  mixed  with  other  minerals  for  profitable 
extraction.  Only  two  of  the  several  known  varieties  of  mica, 
muscovite  (H2KAl3Si3Oi2)  and  phlogopite  (H6K6Mg7Al2(Si04)7), 
are  of  economic  value,  the  former  only  being  found  in  deposits 
of  commercial  value,  in  the  United  States.  Both  phlogopite  and 
muscovite  are  found  in  Canada,  but  only  the  former  is  of  much 
commercial  importance.  The  India  mica,  which  is  shipped  to 
the  United  States  is  muscovite. 

The  commercial  deposits  of  muscovite  are  found  in  pegmatites, 
cutting  granites,  gneisses,  and  schists.  In  these  the  mica  is  asso- 
ciated with  quartz  and  feldspar  (usually  orthoclase  or  micro- 
cline,  more  rarely  plagioclase) ,  being  found  in  rough  crystals  called 
blocks  or  books,  and  which  are  either  irregularly  distributed 
through  the  vein  or  collected  near  its  sides. 

In  addition  to  the  quartz  and  feldspar,  other  minerals  such  as 
tourmaline,  beryl,  zircon,  columbite,  samarskite,  uranium  min- 
erals, garnet,  etc.,  are  sometimes  present.  The  pegmatite,  which 
carries  the  mica,  and  may  be  of  igneous  or  gas-aqueous  origin, 
occurs  as  lenses,  veins,  irregular  masses,  etc.,  of  varying  thickness 
and  length.  The  value  of  the  deposit  depends  more  on  the 
abundance  and  quality  of  the  mica  than  the  size  of  pegmatite 
body. 

The  best  mica  is  obtained  from  the  more  coarsely  crystalline 
rocks;  but  the  widest  veins  do  not  necessarily  contain  the  largest 
blocks.  As  a  rule  the  mica  does  not  form  more  than  10  per  cent 
of  the  vein,  and  usually  not  more  than  10  or  15  per  cent  of  that 
mined  can  be  cut  into  plates,  the  rest  being  classed  as  scrap  mica. 

There  has  been  some  discussion  as  to  whether  the  pegmatites 
are  true  igneous  dikes  or  veins,  but  the  matter  cannot  be  said  to 
be  definitely  settled  in  all  cases.  It  is  probably  that  each  type 
of  origin  is  represented. 


MINOR  MINERALS  365 

The  phlogopite  mica  of  Canada  is  found  in  veins  or  dikes  of 
pyroxene  cutting  gneiss  or  limestone.  Its  chief  associate  is 
apatite,  occurring  in  a  granular  form  or  large  rough  crystals. 
Other  minerals  present  in  smaller  amounts  are  calcite,  scapolite, 
tourmaline,  titanite,  and  even  sulphides.  The  deposits  are 
genetically  similar  to  the  apatite  scapolite  veins  of  Norway.  In 
these  the  phlogopite  occurs  in  the  same  irregular  manner  as  the 
muscovite  in  pegmatites. 

The  value  of  a  mica  deposit  depends  on  the  abundance  and 
size  of  the  books,  perfection  of  cleavage,  color  and  clearness. 
Large  sheets  of  mica  are  the  exception  rather  than  the  rule. 

Mica  may  show  several  internal  structures  which  affect  its 
market  value.  These  are: 

(1)  "  A "  structures,  which  are  striations  or  slight  ridges 
appearing  on  cleavage  faces,  and  following  definite  crystallo- 
graphic  lines,  meeting  to  form  a  "  V."  (2)  Herring-bone  struc- 
ture, similar  to  the  preceding,  but  with  a  third  set  of  striations 
bisecting  the  obtuse  angle  of  the  "  A."  (3)  Ruled  mica,  result- 
ing from  the  development  of  partings,  and  forming  a  series  of 
straight,  sharp,  parallel  cracks  which  cut  through  the  book,  at 
an  acute  angle  to  the  cleavage  face. 

Large  mica  crystals  may  include  smaller  ones,  or  also  grains 
or  crystals  of  other  minerals.  Mica  containing  minute  inclusions 
is  known  as  specked  mica.  These  inclusions  may  be  dendritic  in 
character. 

Distribution  in  the  United  States.  —  Deposits  of  mica  have 
been  worked  in  a  number  of  states  both  east  and  west,  and  yet 
but  few  are  steady  producers.  The  more  important  ones  may  be 
described. 

North  Carolina  (4,  9). — The  mica  mined  in  this  state,  which  is 
the  leading  producer,  comes  from  three  belts  (Fig.  118);  viz.,  the 
Cowee-Black  Mountain,  the  Blue  Ridge,  and  the  Piedmont  belts. 
That  from  the  first  is  chiefly  clear  and  of  light  color  ("  wine  " 
or  "rum  ") ;  that  from  the  second  is  dark  smoky  brown  and  often 
more  or  less  speckled,  while  that  from  the  third  is  often  of  good 
quality  and  similar  to  the  Cowee-Black  Mountain  product.  Ow- 
ing to  a  frequent  capping  of  residual  soil,  discovery  of  the  deposits 
is  difficult. 

The  mica-bearing  pegmatites  occur  in  mica,  garnet,  cyanite, 
hornblende,  and  granite  gneisses  and  schists,  all  of  Archaean  age, 
the  important  formations  being  the  Carolina  and  Roan  gneisses. 


366 


ECONOMIC   GEOLOGY 


The  rocks  of  these  two  are  interbanded  with,  and  cut  by,  streaks  of 
granitic  or  pegmatitic  material,  the  latter  forming  lenticular  bodies 


Chiefly  clear  rum-  Areas  of  principal     Chiefly  dark-colored 
colored.mica  production  or  specked  mica 

FIG.  118.  —  Map  showing  areas  in  North  Carolina  in  which  mica  has  been  mined. 
(After  Sterrett,  U.  S.  Geol.  Surv.,  Bull.  315.) 

or  vein-like  deposits,  which  may,  or  may  not  be  conformable  with 
the  schistosity  of  the  country  rock. 


Mica  gneiss,  wall         Pegmatite  Mica  pockets 

rock  and  horses       Mica  pocket* 


Quartz  Solid  granular 

mica  in  quarts 


FIG.  119. — Section  across  pegmatite  at  Thorn  Mountain  mine,  Macon  Co.,  N.  Ca. 
(After  Sterrett,  U.  S.  GeoL  Surv.,  Bull  315.) 

While  they  vary  in  size,  1  to  2  feet  seems  to  be  the  minimum 
workable  limit  for  rich  and  regular  "  veins."  The  muscovite, 
which  is  the  main  mica  present  (biotite  being  the  other),  shows  a 
variable  mode  of  occurrence.  At  one  time  it  is  evenly  distributed 


MINOR  MINERALS 


367 


through  the  pegmatite,  at  another  large  crystals  are  found  in 
clusters  scattered  through  the  vein  (Fig.  119). 

The  better  grades  of  North  Carolina  mica  are  used  for  the  glazing 
industry,  while  the  less  perfect  sheet  material  is  employed  for  elec- 
trical work.  The  pegmatite  veins  also  carry  a  number  of  rare  min- 
erals. 

South  Dakota  (8) . — Mica  is  mined  in  the  region  around  Custer, 
South  Dakota.  The  muscovite,  as  is  usual,  occurs  in  pegmatite, 
cutting  schists  and  gneisses,  and  granite.  The  material  is  of 
evenly  granular  texture,  or  shows  an  irregular  segregation  of  the 
minerals,  with  but  little  banding.  This  latter  is  sometimes 


Mica  gneiss 


FIG.  120.  —  Generalized  cross  section  of  No.  1  or  New  York  Mine,  near  Custer 
South  Dakota.     (After  Sterrett,  U.  S.  GeoL  Surv.,  Bull.  380.) 

roughly  produced  by  a  segregation  of  the  mica  along  the  walls  of 
the  deposit.  Very  few  of  the  pegmatites  around  Custer,  however, 
carry  enough  mica  to  pay  for  working  them. 

In  the  New  York  mine  (Fig.  120),  for  example,  the  rough  mica 
obtained  along  the  walls  amounts  to  6  or  7  per  cent,  while  the 
interior  portion  of  the  pegmatite  carries  about  0.5  per  cent,  and 
is  not  worked.  The  shape  of  the  pegmatite  bodies  around  Custer 
is  variable,  but  in  general  they  resemble  the  dike  type,  and  appear 
to  represent  an  end  phase  of  the  granite  intrusions  of  that  region, 
for  they  not  only  cut  the  granite  itself,  but  in  places  grade  into  it. 
Their  age  is  not  definitely  known. 

Other  States.  —  Mica  in  pegmatite  has  been  worked  at  Mica  Hill,  4  miles 
northwest  of  Canon  City,  Colorado,  and  6  miles  north  of  Texas  Creek.  That 
obtained  at  the  former  locality  is  peculiarly  adapted  to  grinding  purposes  (10). 
The  Virginia  (12)  occurrences,  especially  those  in  Amelia  and  Henry 
counties,  are  of  some  importance.  That  found  near  Amelia  Court  House 
and  at  Eidgway,  Henry  County,  occurs  in  pegmatite  dikes,  which  inter- 


368  ECONOMIC   GEOLOGY 

sect  the  biotite  gneiss  of  the  district.  The  largest  dikes  are  more  than 
50  feet  wide,  and  the  mica  occurs  in  them  as  thick,  highly  cleavable  blocks, 
and  masses  of  varying  size.  Deposits  are  also  known  to  occur  in  northwest 
Georgia  (4),  and  while  they  resemble  the  North  Carolina  deposits,  they  have 
not  been  worked  much. 

Distribution  in  Canada  (2).  —  Muscovite  deposits  are  found 
quite  widely  distributed  over  the  Dominion,  where  the  pre- 
Cambrian  crystalline  rocks  are  exposed.  They  have  been  worked 
at  a  number  of  localities,  but  are  of  little  commercial  importance 
at  the  present  time. 

Fhlogopite  deposits  are  confined  to  two  areas,  viz.:  (1)  The 
Quebec  area  lying  between  the  Gatineau  and  Lievre  rivers; 
and  (2)  the  Ontario  area  lying  principally  east  of  the  Kingston 
and  Pembroke  Railway. 

The  most  important  mine  in  Canada,  is  that  worked  at  Syden- 
ham,  Ont.  (PL  XXXII,  Fig.  2),  which  has  attained  a  depth  of 
nearly  200  feet.  The  only  other  important  active  one  is  in  Tem- 
pleton  township  northeast  of  Ottawa. 

In  the  Sydenham  mine  the  mica  "  lead  "  varies  from  a  few 
inches  to  25  feet  in  width,  being  at  times  almost  a  solid  mass  of 
enormous  mica  crystals.  The  mica  is  mottled,  wine-amber,  and 
occurs  in  a  greenish-gray  pyroxenite.  Bunches  of  massive  apa- 
tite are  occasionally  met,  and  these  are  mixed  with  white  calcite. 

Other  Foreign  Deposits.  —  The  leading  world's  producer  is  Bengal,  where 
muscovite  mica  has  been  obtained  for  many  years.  It  is  found  associated 
with  quartz,  feldspar,  and  kaolin,  in  pegmatite  veins  cutting  gneisses  and 
schists.  Much  muscovite  has  also  been  obtained  from  the  pegmatite  veins 
of  German  East  Africa  (3). 

Mining  and  Uses  (2).  —  The  irregularity  of  its  occurrence 
makes  mica  mining  somewhat  uncertain.  This  often  leads  to  the 
type  of  mining  known  as  ground  hogging  or  gophering.  The 
rough  crystals  obtained  from  the  mine  range  in  size  from  small 
crystals  to  blocks  several  feet  across.  These  rough  crystals  are 
cobbed  and  cleaned,  and  then  split  into  plates  about  one  sixteenth 
inch  thick.  The  plates  then  have  the  rough  edges  cut  off,  and 
after  grading  as  to  size  and  quality  are  ready  for  further  splitting 
and  trimming.  Mica  can  be  split  into  sheets  one  five-hundredth 
of  an  inch  or  even  less  in  thickness. 

The  chief  use  of  sheet  mica  is  for  electrical  purposes,  it  being 
employed  as  an  insulating  material  in  dynamos,  motors,  high- 
voltage  induction  apparatus,  switchboards,  lamp  sockets,  etc. 


MINOR   MINERALS 


369 


The  domestic  product  is  found  to  be  uniformly  satisfactory  for 
electrical  work,  except  for  insulation  between  the  copper  bars  of 
commutator  segments.  This  use  seems  to  be  best  served  by  the 
amber  or  phlogopite  mica  of  Canada  and  that  of  Ceylon.  The 
superiority  of  this  variety  is  due  to  its  easier  wearing  qualities, 
which  cause  it  to  wear  down  even  with  the  copper  segments.  Mi- 
canite  or  mica  board  is  sheet  mica  obtained  by  cementing  small 
clear  pieces  of  scrap  mica  together  under  pressure.  Since  it  can  be 
bent,  rolled,  and  punched,  it  is  utilized  mostly  for  the  same  pur- 
poses as  sheet  mica.  The  use  of  mica  for  stove  doors  and  chimneys 
is  decreasing,  although  the  glazing  industry  still  demands  a  con- 
siderable amount  of  the  finest  grades  of  sheet  mica.  Scrap  mica 
is  ground  for  use  in  the  manufacture  of  wall  papers,  lubricants, 
fancy  paints,  and  micanite.  That  used  for  electrical  work  must 
be  free  from  metallic  minerals,  and  that  for  wall  paper  and  paints 
must  have  sufficient  luster. 

Ground  mica  is  also  used  in  rubber  goods  as  an  adulterant, 
while  mixed  with  shellac  or  plaster  it  is  employed  in  the  form  of 
moulded  mica  for  insulation  of  trolley  wire.  Tar  and  other  roofing 
papers  may  be  coated  with  coarse  flakes  of  bran  mica  to  prevent 
sticking  when  rolled  for  shipment.  Micarta  is  a  mica  product 
used  as  a  substitute  for  hard  fiber,  glass,  porcelain,  hard  rubber, 
etc.,  for  use  in  commutators  and  other  parts  of  electrical  apparatus. 

Production  of  Mica.  —  The  quantity  and  value  of  mica  pro- 
duced in  the  United  States  from  1910  to  1914  by  kinds  is  given 
below.  The  complete  production  by  states  is  not  given  by  the 
United  States  Geological  Survey. 

PRODUCTION  OF  MICA  IN  THE  UNITED  STATES  FROM  1910  TO  1914 


SHEET  MICA 

SCRAP  MICA 

TOTAL 
VALUE 

Quantity 

Value 

Quantity 

Value 

1910    . 
1911     .... 
1912     .... 
1913     .... 
1914     .... 

Pounds 
2,476,190 
1,887,201 
845,483 
1,700,677 
556,933 

$283,832 
310,254 
282,823 
353,517 
277,330 

Short  Tons 
4065 
3512 
3226 
5322 
3730 

$53,265 
45,550 
49,073 
82,543 
51,416 

$337,097 
355,804 
331,896 
436,060 
328,746 

The  value  of  the  mica  produced  in  Canada  was:  1912,  $143,- 
976;  1913,  $194,304;  1914,  $102,315. 

The  average  price  of  sheet  mica  in  the  United  States  in  1914  was 
50  cents  per  pound,  as  compared  with  20.8  cents  in  1913  and  33.4 


370 


ECONOMIC   GEOLOGY 


cents  in  1912.  The  average  prices  for  the  individual  states  vary 
greatly  from  year  to  year,  due  in  part  to  variation  between  propor- 
tion of  rough  and  trimmed  mica,  and  size  of  sheets  produced.  The 
prices  per  pound  of  several  sizes  of  1st  and  2d  grade  North 
Carolina  mica  in  1913  were  as  follows: 

2X2  in.,  $0.30;  2X3  in.,  $.70;  3X3  in.,  $1.15;  3X4  in., 
$1.35;  4X6  in.,  $2.25;  6X8  in.,  $4.00;  8X10  in.,  $6.00. 

The  imports  of  mica  are  given  for  the  last  five  years,  since  to 
state  those  of  one  year  would  not  clearly  show  the  fluctuations. 

MICA  IMPORTED  AND  ENTERED  FOR  CONSUMPTION  IN  THE  UNITED  STATES, 
1910-1914,  IN  POUNDS 


YEAR 

UNMANUFACTURED 

CUT  OR  TRIMMED 

TOTAL 

Quantity 

Value 

Quantity 

Value 

Quantity 

'"  Value 

1.910    . 
1911     .     .     . 
1912     .     .     . 
1913     .     .     . 
1914     .     .     . 

1,424,618 
1,087,644 
1,900,500 
2,047,571 
360,888 

$460,694 
346,477 
649,236 
751,092 
168,591 

536.905 
241,124 
88,632 
i 

i 

$263,831 
155,686 
99,737 
191,926 
456,805 

1,961,523 
1,328,768 
1,989,132 

$724,525 
502,163 
748,973 
943,018 
625,396 

1  Quantity  not  reported. 

The  exports  of  mica  from  Canada  in  1914  amounted  to  669,163 
pounds  valued  at  $178,940. 

REFERENCES    ON    MICA 

1.  Ball,  U.  S.  Geol.  Surv.,  315:  423,  1907.  (Wyo.)  2.  de  Schmid,  Mica 
Its  Occurrence,  Exploitation  and  Uses.  Dept.  Inter.,  Mines  Branch 
Can.,  No.  118,  1912.  (Can.  and  general.)  Also  Can.  Mines  Branch 
Sum.  Kept.  1913:  42,  1914.  (Brit.  Col.)  3.  Colles,  Mica  and  the 
Mica  Industry,  New  York,  1906.  (General.)  4.  Galpin,  Ga.  Geol. 
Surv.,  Bull.  30,  1915.  (Ga.)  5.  Hoskins,  Min.  Indus.,  X:  458,  1902. 
(N.  H.)  6.  Pratt,  Mineral  Census,  1902,  Mines  and  Quarries:  1031, 
1904.  (General.)  7.  Sterrett,  U.  S.  Geol.  Surv.,  Bull.  580:  65,  1915. 
(U.  S.)  8.  Sterrett,  U.  S.  Geol.  Surv.,  Bull.  380:  382,  1909.  (S. 
Dak.)  9.  Sterrett,  U.  S.  Geol.  Surv.,  Bull.  315:  400,  1907.  (N. 
Ca.)  10.  Sterrett,  U.  S.  Geol.  Surv.,  Min.  Res.,  1908.  (Colo.)  11. 
Sloan,  S.  Ca.  Geol.  Surv.,  Ser.  IV,  Bull.  2:  142,  1908.  (S.  Ca.)  12. 
Watson,  Min.  Res.  Va.,  1907:  278.  (Va.) 


MINERAL   PAINTS 

Under  this  head  are  included  a  number  of  mineral  substances 
which  are  used  in  the  manufacture  of  paints.     Some  of  these  can  be 


MINOR  MINERALS 


371 


used  directly  after  cleaning  and  grinding,  while  others  are  roasted  to 
give  the  desired  color. 

The  substances  used  and    considered    in  this  chapter    include 
ocher,  umber,  sienna,  hematite,  siderite,  ground  slate,  and  shale. 
Other  substances  used  in  the  paint  trade,  but  mentioned  elsewhere, 
are  asbestos  (p.  298),  asphalt  (p.  117),  barite  (p.  309),  clay  (p. 
170),  graphite  (p.    344),  gypsum   (p.  244),  magnesite   (p.  355), 
pyrite  (p.  400),  silica  (p.  390),  talc  (p.  407),  and  whiting. 

Hematite.  —  Certain  kinds  of  hematite,  such  as  the  Clinton  ore 
(see  Iron  Ores),  are  ground  and  sold  under  the  name  of  metallic 
paints,  and  much  used  for  coating  wooden  surfaces  and  coloring 
mortar.  The  ores  are  sometimes  roasted  before  grinding  to  improve 
their  color  and  durability.  Although  hematite  deposits  are  wide- 
spread, and  sometimes  of  large  size,  the  quantity  of  material  show- 
ing the  necessary  uniformity  of  color,  freedom  from  grit,  etc.,  re- 
quired for  mineral  paint  is  small.  Much  crude  material  is  supplied 
by  the  Clinton  ore  mines  at  Clinton  and  Ontario,  New  York  (8). 

At  some  localities  in  northwest  Georgia  and  southeast  Tennes- 
see the  Clinton  oolitic  hematite  occurs  in  beds  too  thin  to  be  now 
mined  for  iron  ore,  but  its  softness,  high  percentage  of  iron  oxide  and 
color  make  it  available  for  red  paint  (3). 

The  following  analyses  show  the  composition  of  this  material. 


I 

II 

in 

Feo03  .... 

7286 

83.14 

80.00 

SiO2     

21.00 

11.90 

16.45 

P    

.40 

.28 

Mn      

.30 

I.  Estelle,  Ga.    II.  Ooltewah,  Term.    III.  Hindi's  Switch,  Tenn. 

Ochers.  —  The  term  ocher,  as  commonly  used,  includes  the 
earthy  and  pulverulent  forms  of  the  minerals  hematite  and  limon- 
ite.  More  or  less  clayey  matter  is  usually  present. 

Properties  and  Occurrence. — The  ochers  show  a  variety  of  colors, 
depending  mainly  on  the  chemical  composition.  Thus  hematites 
give  a  deep  red  color,  while  limonites  have  some  shades  of  yellow  or 
brown,  but  whatever  the  color,  uniformity  of  tint  is  necessary. 
Ochers  may  contain  as  much  as  50  to  75  per  cent  iron  oxide  (10). 
Brown  ocher  or  umber  is  colored  by  manganese,  and  sienna  is  a 
yellowish-brown  variety. 


372 


ECONOMIC  GEOLOGY 


Ochers  may  result  from  (5,  10) :  the  leaching  action  of  percolat- 
ing waters  and  subsequent  deposition;  as  residual  products,  formed 
by  the  removal  or  solution  of  the  soluble  parts  of  the  original  rock, 
leaving  the  insoluble  portions,  clay  and  iron  oxide,  to  form  the 
different  ocherous  colored  clays;  from  the  decomposition  of  rocks 
rich  in  iron-bearing  silicates;  by  oxidation  of  beds  of  pyrite;  by 
alteration  or  decomposition  of  hematite  beds;  by  alteration  of  more 
compact  forms  of  limonite;  by  replacement;  by  sedimentation. 

Distribution  of  Ocher.  —  Georgia  and  Pennsylvania  are  the 
largest  producers  of  ocher,  but  California,  Vermont,  and  other 
states  help  to  swell  the  total. 

Georgia  (5,  6, 10) .  —  In  this  state  the  ocher  deposits  occur  in  a 
north-south  belt,  8  miles  long,  lying  east  and  southeast  of  Carters- 
ville.  The  ocher  is  limited  to  the  Weisner  (Cambrian)  quartzite, 
in  which  it  occupies  an  extensively  shattered  zone  of  similar  posi- 


FIG.  121.- 


-Section  showing  relations  of  ocher,  quartzite,  and  clay,  near  Cartersville, 
Ga.     (After  Watson,  Ga.  Geol.  Surv.,  Butt.  13.) 


tion  to  that  of  the  residual  clay  derived  from  the  rock  decay  (Fig. 
121).     The  following  analyses  represent  its  composition. 

ANALYSES  OP  GEORGIA  OCHER 


I 

II 

in 

Fe^Os       

7229 

56.29 

61.40 

Al2Os  

5.55 

10.15 

7.14 

FeO     

.46 

.39 

MnOo 

87 

54 

2.00 

SiO2  (free  sand) 

665 

894 

11.89 

SiO2  (comb)  .... 

398 

949 

5.84 

Moist  

55 

208 

.46 

H2O  above  105°  C  

922 

11.34 

9.37 

99.57 

99.22 

98.10 

I.  Crude  ocher,  Mansfield  Bros.,  Lot.  462,  4th  dist.,  3d  sec.  Bartow  Co. 
II.  Crude  ocher  near  Emerson,  Bartow  Co.  III.  Refined  ocher,  Blue  Ridge 
Ocher  Co. 


MINOR  MINERALS  373 

The  average  percentage  of  limonite  in  a  number  of  analyses  was 
74.15  per  cent  for  both  the  crude  and  refined  ocher.  There  is  ad- 
mixed with  it  about  20  per  cent  of  clay  and  finely  divided  quartz 
which  cleansing  will  not  eliminate.  The  ocher  of  this  district 
ranges  from  a  dark  to  a  light  yellow  color  dependent  chiefly  on  the 
amount  of  admixed  clay. 

According  to  Watson  (10),  the  Bartow  County  ocher  deposits 
have  been  formed  by  molecular  replacement  of  the  quartzite,  and 
subsequent  weathering  has  resulted  in  the  ocher  bodies  being  in- 
closed in  many  cases  in  residual  clays  derived  from  the  decay  of  the 
original  rock.  Hayes  (5)  states  that  the  ocher  forms  a  series  of 
irregular -branching  veins,  extending  in  all  directions,  but  often  ex- 
panding into  bodies  of  considerable  size. 

It  is  believed  by  Watson  (10)  that  the  iron  oxide  of  the  ocher  was 
derived  largely  from  the  decay  of  surface  rocks  and  carried  down- 
ward by  surface  waters  in  the  form  of  soluble  ferrous  salts,  but  that 
some  was  probably  contributed  by  pyrite  in  the  quartzite.  The 
deposition  may  have  been  due  to  the  carbon-dioxide  solution  of 
ferrous  carbonate  meeting  an  oxidizing  solution,  resulting  in  a 
precipitation  of  the  iron  and  a  solution  of  the  silica  of  the  quart- 
zite.1 

The  main  use  of  the  Georgia  yellow  ocher  is  in  the  manufacture 
of  linoleum  and  oilcloths,  especially  in  England  and  Scotland.  It 
is  employed  to  a  limited  extent  for  paint  manufacture. 

Pennsylvania.  —  The  ocher  deposits  of  eastern  Pennsylvania 
include  the  residual  deposits  of  the  Reading-Allentown  district  and 
the  bedded  deposits  of  the  Moosehead  district  The  first  named 
includes  the  principal  ocher  belt  of  Pennsylvania  and  lies  in  Berks 
and  Lehigh  counties,  where  the  ocher  deposits  occur  as  irregular 
masses  in  a  residual  clay  derived  from  the  Shenandoah  (Cambro- 
Silurian)  limestone.  Associated  with  the  ochers  are  nodules  and 
geodes  of  limonite,  as  well  as  smaller  quantities  of  turgite,  ilmenite, 
siderite,  and  pyrite.  The  product  after  washing,  drying,  and  grind- 
ing contains  from  12  to  30  per  cent  Fe2C>3. 

In  the  Moosehead  area  a  bed  of  soft,  buff-colored  shale,  found  at 
the  base  of  the  Mauch  Chunk  shale,  and  resting  on  the  Pocono 
sandstone  (Lower  Carboniferous) ,  is  mined  for  paint.  It  is  of  low 
grade,  and  the  product  carries  from  6  to  7  per  cent  ferric  oxide. 

Umber  and  sienna  have  been  produced  in  small  quantities  in 

1  Van  Hise,  Treatise  on  Metamorphism,  p.  417. 


374 


ECONOMIC  GEOLOGY 


Illinois  and  Pennsylvania,  and  sienna  in  addition  has  been  ob- 
tained from  New  York. 


ANALYSES  OF  MINERAL  PAINTS  FROM  PENNSYLVANIA 


I 

II 

III 

IV 

V 

SiO2  .... 
Fe203.     .     .     . 
FeS2  .... 
A1203      .     .     . 
MgO      .     .     . 
CaCO3    .     .     . 
r^aO 

39.70 
37.64 

12.36 
1.37 

39.00 
42.35 

13.33 
tr. 

57.53 
4.52 
3.76 
16.72 
1.38 
4.12 

64.24 
4.80 

22.40 

75.52 
4.95 

9:85 
1.29 

197 

"Mo  O 

1OA 

.  At 

iNa2L/ 
K2O  .... 





2.12 

31Q 



.64 

2.02 

Water    .     .     . 

7.83 

2.50 

5.70 

3.14 

I.  Ocher,  Easton,  Pa.;  II.  Same  after  burning;  III.  Black  shale,  Muncy. 
Pa.;  IV.  Yellow  shale,  Moosehead,  Pa.;  V.  Red  shale,  East  Charles- 
ton, Pa. 

Canada  (12).  —  Ochers  are  found  in  many  parts  of  Canada, 
but  the  worked  deposits  are  confined  to  those  found  between 
between  Champlain  and  Three  Rivers,  Quebec.  In  Ontario 
small  quantities  have  been  occasionally  obtained  from  near 
Campbell  ville. 

Siderite  (1).  —  In  Southern  Carbon  County,  Pa.,  there  occurs  a 
somewhat  extensive  but  not  very  thick  bed  of  siderite  lying  between 
the  Oriskany  (Devonian)  and  Hamilton  (Devonian)  formations. 
The  section  shows 

Cement  rock 25  feet 

Paint  "ore" 2  feet 

Clay 8  feet 

35  feet 

The  brown  paint  "  ore,"  which  consists  chiefly  of  iron  carbonate, 
varies  in  thickness,  often  between  1  and  2j  feet,  and  rarely  reaching 
4  feet.  It  is  in  places  changed  to  limonite  at  the  surface,  and  grows 
leaner  with  depth,  leading  to  the  belief  that  it  represents  a  replace- 
ment of  limestone  by  surface  waters. 


MINOR   MINERALS 


375 


Below  are  given  (I)  an  analysis  of  the  crude  ore  (7),  and  (II)  an 
analysis  of  the  roasted  product  (4). 

ANALYSES  OF  SIDERITE  PAINT  "ORE"  FROM  PENNSYLVANIA 


I 

ii 

Fe    .     .     .     .     ... 

34.60 

Fe9O3  

42.70 

Mn  

.929 

MnO  

1.40 

SiO*      

16.21 

SiO2     ...... 

3720 

AloO3 

5492 

Al2Os 

940 

CaO      

3.51 

CaO     

1.70 

MgO     

1.081 

MgO    

1.70 

S      .     .              .     . 

674 

SOs      .          .          .     . 

1.88 

p 

018 

P?O5 

14 

Loss  on  roasting 

24.35 

H..O 

.60 

CO2        

2.60 

86.854 

99.32 

This  paint  is  used  mainly  for  freight  cars,  and  in  lesser  amounts 
for  painting  steel,  tin,  boats,  and  as  a  filling  in  oilcloth  and  linoleum. 

Slate  and  Shale.  —  The  refuse  from  slate  quarries  is  sometimes  ground 
and  sold  as  a  pigment,  and  in  some  localities  shales  of  the  proper  color  and 
texture  are  utilized  for  the  same  purpose.  Their  value  depends  on  their 
color,  fineness,  and  amount  of  oil  required  in  mixing.  They  are  also  used 
as  fillers  in  the  manufacture  of  oil  cloth  and  linoleum. 

Pennsylvania  and  New  Jersey  are  the  chief  producers.  The  Hamilton 
(Devonian)  shales  have  been  worked  for  some  years  in  Cattaraugus 
County,  N.  Y.,  and  a  product  known  as  mineral  black  is  made  from  the 
slates  of  the  Hudson  River  (Ordovician)  series. 

Pennsylvania  yields  over  90  per  cent  of  the  United  States  production. 
The  shales  used  are  classed  as  black  (mineral  black),  yellow  and  red.  The 
refuse  from  slate  quarries  and  the  culm  from  anthracite  mines  has  also 
been  used  by  paint  manufacturers. 

Gypsum,  known  also  as  terra  alba  or  mineral  white,  is  used  to  some 
extent  as  a  pigment  for  printing  wall  paper. 

Barite,  or  barium  sulphate,  which  is  used  as  an  adulterant  of  white 
lead,  is  purified  after  mining  by  grinding  and  washing. 

Asbestos  is  used  to  some  extent  in  paint  manufacture  for  the  so-called 
non-inflammable  or  fireproof  paints,  but  the  total  quantity  thus  utilized 
is  small. 

Graphite,  either  natural  or  artificial,  supplies  a  black  pigment  of  per- 
manent color  which,  on  account  of  its  resistance  to  the  atmosphere  and 
ordinary  chemicals,  is  of  much  value  for  coating  oxidizable  metals,  such 
as  iron  and  steel. 


376 


ECONOMIC   GEOLOGY 


Calcium  Carbonate,  in  the  form  of  chalk,  known  commercially  as  whiting 
or  paris  white,  is  used  as  a  pigment  to  alter  the  shade  of  other  pigments 
as  a  basis  for  whitewash. 

Kentucky,  Michigan  and  Missouri  produced  whiting  in  1914,  but  all  of  it 
was  not  used  as  pigment.  Whiting  may  be  prepared  by  grinding  different 
kinds  of  white  limestone,  but  it  is  not  as  fine  grained  or  as  light  in  weight 
as  the  artificially  prepared  material.  A  fine-grained  rhyolitic  tuff  has  been 
produced  in  Los  Angeles  County,  Calif.,  for  white  pigment. 

Other  Paints.  —  Paints  sometimes  classed  as  mineral  paints  are  made 
from  other  crude  minerals,  as  follows:  zinc  white  from  zinc  ore;  white 
lead,  red  lead,  and  orange  mineral  from  lead;  Venetian  red  from  iron  sul- 
phate; vermilion  or  artificial  cinnabar  from  quicksilver;  chrome  yellow 
from  chromite;  cobalt  blue  from  cobaltite. 

Production  of  Mineral  Paints.  —  The  production  of  mineral 
paints,  as  well  as  the  imports,  are  given  below. 

PRODUCTION  OF  NATURAL  MINERAL  PIGMENTS,  1909-1914,  IN  SHORT  TONS 


PIGMENT 

19 

39 

19 

10 

19 

LI 

Quantity 

Value 

Quantity 

Value 

Quantity 

Value 

Ocher  .... 
Umber      .     .     . 
Sienna 
Metallic  paint  . 
Mortar  colors    . 
Slate  and  shale 
(ground)    . 

12,458 
}      1,276 

20,722 
10,820 

14,944 

$125,349 
33,472 

201,905 
108,126 

98,176 

11,711 
1,015 

29,422 
9,960 

16,515 

$112,445 
26,700 

184,869 
107,780 

96,001 

$11,703 
1,005 

25,599 
7,922 

16,510 

$109,465 
26,225 

181,163 
76,517 

105,451 

Total     .     . 

60,220 

$567,028 

68,623 

$527,795 

62,739 

$498,821 

PIGMENT 

19 

12 

19 

13 

19 

14 

Quantity 

Value 

Quantity 

Value 

Quantity 

Value 

Ocher  .... 
Umber 
Sienna       .      .      . 
Metallic  paint  . 
Mortar  colors    . 
Slate  and  shale 
(ground)    . 

15,269 

1         805 

28,347 
9,272 

20,964 

$149,289 
21,975 

181,352 
87,595 

121,482 

17,578 
776 

30,098 
5,357 

16,786 

$173,944 
20,790 

171,264 
35,443 

120,969 

14,387 
790 

30,947 
5,371 

15,271 

$136,185 
21,070 

179,653 
47,723 

88,405 

Total     .     . 

74,657 

$561,693 

70,595 

$512,410 

66,766 

$473,036 

IMPORTS  IN  1913  AND  1914,  POUNDS 


Quantity 

Value 

Quantity 

Value 

Ocher 

16,697,098 

$143,720 

22,066,006 

$141.704 

Umber 

5  236,489 

36,771 

7,886,716 

45,280 

3.273.21Z 

48,535 

7,815,323 

63,958 

1914 


MINOR   MINERALS 
PRODUCTION  OF  CCHERS  IN  CANADA,  1912-1914 


377 


YEAR 

SHORT  TONS 

VALUE 

1912    .... 
1913    .... 
1914    .... 

7654 
5987 
5890 

$32,410 
41,774 
51,725 

World's  Production. — From  the  following  table  of  ocher  and 
umber  production  of  the  principal  producing  counties  in  short 
tons,  it  will  be  seen  that  France  is  the  leading  producer  and  the 
United  States  second. 


COUNTRY 

QUANTITY 

VALUE                  COUNTRY 

QUANTITY 

VALUE 

United  States  (1913) 
United  Kingdom 
(1913)       .      .      . 
France  (1912)  .      . 
German  Empire 
(1912)       .      .     . 

17,963 

16,951 
46,087 

7,668 

$181,404    i 

70,370 
420,248 

14,072 

Canada  (1913)      . 
Belgium  (1912)    . 
Spain  (1912)    .      . 
Cyprus  (1912)       . 

5,987 
716 
661 
5,259 

$41,774 
1,502 
1,168 
20,945 

REFERENCES  ON  MINERAL  PAINTS 

1.  Miller,  Top.  and  Geol.  Com.  Pa.,  Rept.  4,  1911.  (Pa.)  2.  Anon., 
Calif.  State  Min.  Bur.,  Bull.  38:  338,  1906.  (Calif.)  3.  Burchard, 
U.  S.  Geol.  Surv.,  Bull.  315,  Pt.  I:  430,  1907.  (Clinton  ore,  Tenn., 
Ga.)  4.  Eckel,  Ibid.,  Pt.  I:  435,  1907.  (Siderite.)  5.  Hayes,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXX:  415,  1901.  (Ga.  ocher.)  6.  Hayes, 
and  Eckel,  U.  S.  Geol.  Surv.,  Bull.  213:  427,  1903.  (Ga.  ocher.)  7. 
Hill,  Sec.  Pa.  Geol.  Surv.,  Rept.  for  1886,  Pt.  4:  1386,  1887.  (Siderite, 
Pa.)  8.  Newland,  N.  Y.  State  Museum,  Bull.  102:  111,  1906.  (New 
York.)  9.  Stoddard  and  Collen,  U.  S.  Geol.  Surv.,  Min.  Res.  1908, 
Chap.  Mineral  Paints.  (Ocher,  Pa.)  10.  Watson,  Ga.  Geol.  Surv., 
Bull.  13,  1906.  Also  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXXIV:  643, 
1904.  (Ga.  ocher.)  11.  Watson,  Min.  Res.  Va.:  225,  1907.  12. 
Willmott,  Can.  Geol.  Surv.,  Rep.  913,  1906.  (Can.)  13.  Scattered 
notes  in  the  Mineral  Industry  (Annual  published  by  Eng.  and  Min. 
Jour.)  and  in  U.  S.  Geol.  Surv.,  Mineral  Resources.  That  for  1913 
has  bibliography, 


MONAZITE 

Properties  and  Occurrence.  —  This  mineral  is  an  anhydrous 
phosphate  of  the  rare  earth  metals,  cerium,  lanthanum,  praseodym- 
ium and  neodymium;  but  its  economic  value  is  due  chiefly  to  the 
small  amount  of  thoria  which  it  contains.  The  percentage  of 
thoria  in  monazite  ranges  from  less  than  1  to  20  or  more,  and  in 


378 


ECONOMIC   GEOLOGY 


commercial  monazite  varies  between  3  and  9  per  cent.  Although 
grains  of  monazite  are  found  scattered  through  many  granites  and 
gneisses,  still  no  occurrences  of  this  type  have  thus  far  proven  to  be 
of  commercial  value.  The  economically  valuable  deposits  are  all 
found  in  stream  gravels,  derived  from  the  disintegration  of  mona- 
zite-bearing  rocks.  Monazite  is  usually  light  yellow  to  honey 
yellow,  red,  or  brown  in  color,  has  a  resinous  luster,  a  specific 
gravity  of  5.203  (Penfield  and  Sperry)  and  a  hardness  of  5  to 
5.5.  It  is  very  brittle.  Its  gravity  and  color  aid  in  its  ready 
determination. 

In  the  United  States  deposits  of  monazite  sand  have  been  found 
in  the  granite  and  gneiss  areas  of  North  Carolina  (2,  4)  and  South 
Carolina  (3),  and  these,  together  with  deposits  found  in  Brazil  (1), 
supply  nearly  the  entire  world's  demand.  A  small  quantity  is  also 
obtained  from  southern  Norway,  as  a  by-product  in  feldspar  mining. 
The  following  analyses  indicate  the  composition  of  monazite :  — 

ANALYSES  OF  NORTH  CAROLINA  MONAZITE 


P«0« 

Ce203 

La203 

ThO2 

Si02 

H2O 

Burke  Co.,  N.  C.    .     .     . 

29.28 

31.28 

30.88 

6.49 

1.40 

.20 

Alexander  Co.,  N.  C. 

29.32 

37.26 

31.60 

1.48 

.32 

.17 

The  deposits  known  in  the  Carolinas  have  been  found  within  an 
area  of  about  3500  square  miles  (Fig.  122),  which  lies  wholly  within 
the  Piedmont 
Plateau  region. 
The  chief  rocks 
are  gneisses  of 
different  kinds, 
schists,  granite, 
pegmatite,  peri- 
dotite,  quartz- 
diorite,  and  dia- 
base, but  the 
structural  condi-  —_^^—^^ 

tions  are  Complex,    FIG.    122. —  Map    showing   area   of   monazite   deposits   of 
and     metamor-          known  commercial  value  in  southern   Appalachian   re- 

phism   has   often        gion'    (After  Sterrett>  U'  S'  GeoL  Surv"  BulL  34a) 
obscured  the  original  character  of  the  rocks.     The  latter  are,  more- 
over, often  concealed  by  a  heavy  mantle  of  residual  soil. 


ito  zoo  nnli.-: 


MINOR  MINERALS  379 

Where  the  monazite  has  been  found  in  the  bed  rock,  it  has  been 
chiefly  in  a  porphyritic  pegmatized  gneiss.  In  the  ordinary  gneiss, 
and  in  the  highly  pegmatized  gneiss,  the  monazite  is  far  less  abun- 
dant. These  occurrences  in  bed  rock  have  not,  however,  proved 
to  be  of  commercial  value,  and  the  only  important  deposits  are  the 
placers,  and  gravel  beds  in  the  streams  and  bottom  lands,  as  well  as 
some  surface  soils,  adjoining  the  rich  gravel  deposits. 

In  some  areas  the  saprolite  or  rotted  rock  underlying  gravel  de- 
posits has  been  washed  with  favorable  results. 

The  monazite-bearing  gravels  range  in  thickness  from  one  to  two 
feet,  including  overburden,  up  to  6  to  8  or  more  feet,  and  the  mona- 
zite on  account  of  its  gravity  has  collected  more  abundantly  in  the 
lower  portion.  The  deposits  are  richest  in  those  regions  contain- 
ing an  abundance  of  granitic  rocks,  pegmatized  gneisses,  and  schists, 
while  in  the  gravel  itself,  the  presence  of  considerable  quartz  debris, 
and  fragments  of  such  rocks  as  pegmatite,  granite,  mica/and  cyanite 
gneiss,  are  favorable  signs. 

In  some  cases  the  supply  of  monazite  in  the  stream  gravels  may  be 
replenished  by  wash  from  the  hillsides  which  are  underlain  by  re- 
sidual soils  containing  monazite  grains. 

The  monazite  found  in  the  pegmatized  gneiss  is  believed  to  have 
been  derived  from  aqueo-igneous  solutions  passing  through  the 
rock,  and  depositing  and  recrystallizing  portions  of  it  into  the  min- 
erals of  pegmatite. 

Uses.  —  Monazite  is  usually  separated  from  the  gravels  by  a 
washing  process,  and  in  addition  magnetic  separation  has  in  some 
cases  been  employed  to  separate  it  from  the  associated  garnet, 
magnetite,  and  quartz. 

The  value  of  monazite  lies  in  the  incandescent  properties  of  the 
oxides  of  the  rare  earths,  cerium,  lanthanum,  didymium,  and  tho- 
rium, which  it  contains,  and  which  are  utilized  in  the  manufacture 
of  mantles  for  incandescent  lights. 

Production  of  Monazite.  —  The  production  of  monazite  de- 
clined from  a  maximum  of  1,352,418  pounds,  valued  at  $163,908 
in  1905,  to  99,301  pounds,  valued  at  $12,006  in  1910,  since  which 
time  there  has  been  no  production  in  the  United  States,  the  gas 
mantle  industry  having  been  supplied  by  imports  from  Brazil. 

REFERENCES    ON    MONAZITE 

1.  Dennis,  Min.  Indus.,  VI:  487,  1898.  (General.)  2.  Nitze,  N.  C.  Geol. 
Surv.,  Bull.  9,  1895.  3.  Pratt,  U.  S.  Geol.  Surv.,  Min.  Res.,  1902, 
1003,  1903;  and  1903:  1163,  1904.  (N.  Ca.  and  S.  Ca.)  4.  Sterrett: 
U.  S.  Geol.  Surv.,  Bull.  340:  272,  1908.  (N.  Ca.  and  S.  Ca.) 


CHAPTER  XII 
MINOR   MINERALS  —  PRECIOUS   STONES  —  WAVELLITE 

PRECIOUS   STONES 

THE  names  gems  and  precious  stones  (1,  2)  are  applied  to  certain 
minerals,  which  on  account  of  their  rarity,  as  well  as  hardness,  color, 
and  luster,  are  much  prized  for  ornamental  use.  The  hardness  is  of 
importance  as  influencing  their  durability,  while  their  color,  luster, 
and  even  transparency  affect  their  beauty.  A  distinction  is  some 
times  made  between  the  more  valuable  stones,  or  gems  (such  as 
diamond,  ruby,  sapphire,  and  emerald),  and  the  less  valuable,  or 
precious  stones  (such  as  amethyst,  rock  crystal,  garnet,  topaz, 
moonstone,  opal,  etc.). 

Most  gems  are  found  in  unconsolidated  surface  deposits  represent- 
ing either  residual  material  or  alluvium  derived  from  it,  and  in  the 
latter  their  concentration  and  preservation  are  due  to  their  weight 
and  hardness.  When  found  in  solid  rock,  the  metamorphic  and 
igneous  types  are  more  often  the  source  than  the  sedimentary  ones. 

Many  different  minerals  are  used  as  gems  (1,  2),  but  only  a  few 
of  the  important  ones  can  be  mentioned  here,  and  the  number  of  the 
more  valuable  kinds  found  in  the  United  States  is  very  limited 
(4,  12).  Every  year,  however,  discoveries  of  one  kind  or  another  are 
reported,  and  reference  is  usually  made  to  these  in  the  Mineral  Re- 
sources of  the  United  States  published  annually  by  the  United 
States  Geological  Survey. 

Diamond.  —  This  mineral,  which  is  the  hardest  of  all  known 
natural  substances,  is  pure  carbon,  crystallizes  in  the  isometric 
system,  and  has  a  specific  gravity  of  3.525.  It  occurs  in  many 
different  colors,  of  which  white  is  the  commonest,  and  is  found 
either  in  basic  igneous  rocks  or  in  alluvial  gravels. 

The  massive  forms,  known  as  bort  or  carbonado,  have  little  or  no 
cleavage,  and  are  of  value  only  as  an  abrasive. 

The  greatest  number  of  diamonds  come  from  South  Africa,  but 
other  deposits  of  commercial  value  occur  in  India,  Borneo,  and 
Brazil. 

380 


MINOR  MINERALS 


381 


In  the  United  States  a  few  scattered  diamonds  have  been  found 
in  the  drift  or  soil  of  the  southern  Alleghanies,  California,  Wiscon- 
sin, and  Indiana,  but  they  are  all  small  (10,  12,  13,  15). 

Arkansas. — The  only  and  first  locality  in  North  America  where 
diamonds  have  been  found  in  place,  is  in  Pike  County,  Ark. 
(9,  13),  where,  near  Murfrees- 
boro,  several  areas  of  peri- 
dotite are  known  to  occur 
(Fig.  123).  The  first  diamonds 
were  found  in  1906,  and  up 
to  1913,  approximately  1375 
stones,  aggregating  about  550 
carats,  were  reported  to  have 
been  recovered. 

The  sedimentary  rocks  of 
this  area  consist  of  strongly 
folded  Paleozoic  ones,  overlain 
by  Cretaceous  beds,  and  these 
have  been  intruded  by  the 
peridotite.  This  has  in  most 
places  disintegrated  to  a  soft 
earth,  whose  topographic  fea- 
tures, however,  do  not  dif- 
fer from  those  of  the  Trinity 
(Cretaceous)  clay. 

The  residual  clay  derived  from  the  peridotite  is  usually  yellow- 
ish green  above  and  bluish  green  below,  the  solid  rock  being  in 
some  cases  as  much  as  30  feet  deep. 


CARBONIFEROUS 


Alluvium       Bingen     Peridotite     Trinity      Sandstone 
sand  formation 

FIG.  123.  —  Map  of  Arkansas  diamond 
area.  (After  Miser,  U.  S.  Geol.  Surv., 
Bull.  540.) 


Surface 

Trinity    formation 


10  Feet 


FIG.  124.  —  Section  in  Arkansas  diamond  area.     (After  Miser.) 


South  Africa  (5a,  24a).  —  The  Arkansas  diamond  occurrence  resembles 
in  some  respects  some  of  the  South  African  ones.  There  the  gems  have 
been  discovered  at  several  localities,  viz.:  (1)  In  northern  Cape  Colony; 


382  ECONOMIC   GEOLOGY 

(2)  At  Jagerfontein,  Orange  Colony;  (3)  near  Pretoria,  Transvaal;  and 
(4)  In  German  Southwest  Africa. 

In  the  Kimberley  field,  for  example,  the  diamonds  occur  in  volcanic 
necks  or  "pipes''  of  kimberlite.  These  necks  pierce  a  series  of  sandstones, 
lavas,  and  shales,  ranging  from  Carboniferous  to  Triassic  in  age.  The 
upper  part  of  the  kimberlite  is  weathered  to  the  so-called  yellow  ground, 
while  below  it  is  the  unoxidized  rock  or  blue  ground.  The  latter  is  the 
material  now  worked,  and  has  to  be  disintegrated  by  weathering  before 
the  diamonds  can  be  extracted  from  it. 

The  pipes  are  to  be  regarded  as  vents  filled  with  the  products  of  ex- 
plosive eruptions,  and  the  diamond  crystals  disseminated  through  this,  may 
be  crystallizations  from-  the  magma. 

The  Premier  mine,  where  the  conditions  are  similar  to  those  at  Kim- 
berley, has  yielded  the  Cullinan  diamond, — the  largest  ever  found, — weighing 
3024f  carats,  and  measuring  4  by  2  inches. 

The  German  Southwest  Africa  deposits  are  unique  in  that  the  diamonds 
occur  in  a  windblown  sand  and  gravel  resting  on  the  crystalline  bed  rock. 
Their  exact  source,  whether  from  the  crystalline  rocks  of  the  district,  or  a 
hypothetical  basic  igneous  rock  now  below  sea-level,  is  open  to  doubt  (56, 
24a). 

British  Columbia  (7a).  —  A  highly  interesting,  but  not  commercially 
important  occurrence  of  diamonds  has  been  found  at  Olivine  Mountain, 
in  the  Tulameen  district  of  British  Columbia.  The  rock  is  a  serpentinized 
peridotite,  containing  small  segregations  of  chromite,  and  it  is  with,  these 
that  the  diamonds  are  found,  forming  without  doubt  original  constituents 
of  the  igneous  mass.  They  are  all  small,  not  larger  than  a  pin  head,  of 
yellowish  to  brownish  color,  and  partly  or  wholly  opaque.  A  few  have  been 
found  in  the  neighboring  stream  gravels. 

Origin.  —  The  origin  of  the  diamond  has  provoked  much  discussion 
among  scientists,  and  a  number  of  successful  attempts  have  been  made 
to  produce  it  artificially.  These  indicate  its  formation  by  crystallization 
from  a  fused  magma,  which  in  most  cases  has  a  composition  resembling 
peridotite.  As  corroborative  of  this  we  have  the  occurrence  of  South 
African  diamonds  in  or  near  volcanic  pipes  of  peridotitic  character,  and 
Lewis  has  suggested  that  the  stones  were  formed  by  the  solvent  action  of 
the  molten  peridotite  magma  on  carbonaceous  shales.  Some  have  dis- 
puted this  idea,  and  believe  that  the  diamond  is  an  original  constituent  of 
the  magma,  from  which  it  crystallized  on  cooling.  As  opposed  to  an  igneous 
origin  is  the  statement  of  G.  F.  Williams,  that  he  found  an  inclusion  of 
apophyllite  (a  highly  hydrous  mineral)  in  a  Kimberley  diamond.  The 
occurrence  in  British  Columbia,  already  referred  to,  seems  to  leave  little 
doubt  as  to  a  possible  crystallization  from  a  magma.  All  diamonds  do  not 
occur  in  peridotite,  for  in  Brazil  hydromica  schists  and  quartzite  may 
contain  them,  while  certain  Indian  ones  appear  to  have  been  derived  from 
pegmatite,  and  some  Australian  ones  in  hornblende-diabase. 

The  most  that  can  perhaps  be  said  is  that,  while  much  of  the  evidence 
indicates  an  igneous  origin,  the  diamond  has  not  necessarily  been  obtained 
in  all  cases  from  the  same  kind  of  magma. 


MINOR  MINERALS  383 

Emerald.  —  This  gem  is  a  variety  of  beryl,  essentially  a  glucinum- 
aluminum  silicate.  Its  hardness  is  7.5  to  8,  and  its  specific  gravity 
2.5  to  2.7.  Its  brilliant  green  color  is  attributed  by  some  to  chro- 
mium, by  others  to  organic  matter.  Brazil,  Hindustan,  Ceylon, 
and  Siberia  are  all  important  sources.  In  the  United  States  a  few 
have  been  found  in  western  North  Carolina  (12,  15)  in  gravel  de- 
posits. Flawless  emeralds  are  very  rare,  and  equal  in  value  to 
diamonds. 

Aquamarine  and  oriental  cat's-eye  are  also  varieties  of  beryl. 
Brazilian  emerald  is  a  green  variety  of  tourmaline,  and  lithia  emerald 
an  emerald-green  spodumene. 

Beryl.  —  Gem  beryl  has  been  found  at  many  localities  in 
New  England,  and  while  at  some  of  these  it  has  been  obtained  as 
an  accessory  mineral  in  feldspar  mining,  at  others  the  veins  have 
been  worked  for  the  gem  mineral  alone.  Thus  in  Connecticut 
golden  beryl  has  been  obtained  near  New  Milford,  and  good 
aquamarine  near  East  Hampton.  Other  localities  have  been 
worked  in  Maine,  Massachusetts  and  New  Hampshire.1 

Garnet.  —  Of  the  several  varieties  of  garnet,  three  are  well 
known  as  gem  stones,  viz.,  the  precious  garnet,  or  almandite, 
Bohemian  garnet,  or  pyrope,  and  manganese  garnet,  or  spsssart- 
ite.  The  first  two  are  of  deep  crimson,  the  last  of  orange-red  or 
light  red-brown  color.  India  is  the  main  source  of  supply.  All 
three  varieties  mentioned  are  found  in  the  United  States,  but 
there  is  a  regular  production  only  of  the  pyrope  from  Arizona  and 
New  Mexico,  and  a  purple-red  garnet  known  as  rhodolite  from 
North  Carolina  (4,  12,  15) . 

Those  found  in  the  southwest  (22)  have  for  many  years  been 
collected  by  the  Navajo  Indians.  Clear  red  garnets  associated 
with  peridot  gems,  which  have  been  weathered  out  of  basic 
igneous  rocks,  have  been  found  at  several  places  around  and  north 
of  Fort  Defiance,  Arizona,  but  those  obtained  from  these  localities 
are  small  and  not  worth  cutting.  The  supply  of  gem  garnets 
comes  from  close  to  the  Utah- Arizona  line,  at  a  point  12  miles 
southwest  of  the  junction  of  the  Chin  See  Valley  and  San  Juan 
River  in  Utah.  In  this  region,  which  is  underlain  by  sandstone 
of  probable  Triassic  age,  pierced  by  numerous  basic  igneous  rocks, 
the  garnets  are  found  chiefly  in  a  coarse,  unconsolidated  drift  or 
gravel  layer,  associated  with  feldspar,  diopside,  quartz,  and 
igneous  rock  fragments.  The  garnets  range  in  size  from  small 

1  Min.  Res.,  U.  S.  Geol.  Surv.,  1913,  p.  656. 


384  ECONOMIC  GEOLOGY 

grains  to  others  over  3  centimeters  in  diameter,  but  the  gem  stones 
are  not  over  12  millimeters  across. 

Opal,  which  is  hydrous  silica  chemically,  is  amorphous,  with 
conchoidal  fracture,  yellow,  red,  green,  or  blue  color,  and  often 
showing  considerable  iridescence.  The  varieties  recognized  are 
the  precious  opal,  fire  opal,  girasol,  and  common  opal.  The  finest 
examples  of  precious  opal  are  obtained  from  Hungary.  Others 
are  also  found  at  Queretaro,  Mexico,  and  in  Oregon  and  Wash- 
ington. The  United  States  production  is  small,  although  it  is 
thought  that  there  are  many  scattered  occurrences  in  the  igneous 
rocks  of  Washington,  Idaho,  Oregon,  California,  Nevada,  and 
Utah  (4,  12). 

In  1913,1  considerable  prospecting  was  done  in  the  opal 
field  of  Virgin  Creek,  Humboldt  County,  Nevada,  a  region  that 
was  discovered  in  1908.  The  formations  consist  of  tuffs,  ashes 
and  rhyolitic  lavas,  which  have  been  broken  by  block  faulting 
and  tilting,  and  the  opal  occurs  in  the  ash  beds,  mostly  associated 
with  the  petrified  wood.  It  is  found  as  casts  of  different  parts  of 
the  trees,  and  as  coatings  and  filling  in  cracks  in  the  silicified  wood. 

Peridot.  —  This  name  is  applied  to  a  deep  olive-green  variety  of 
chrysolite,  a  silicate  of  magnesium  and  iron.  Peridot  has  a  low 
hardness  (6.75)  as  compared  with  other  gems,  while  its  specific 
gravity,  3.3  to  3.4,  is  relatively  high. 

Gem  peridot  is  found  in  two  regions  in  Arizona  (22)  viz.  north  of 
Fort  Defiance  in  the  Navajo  Indian  Reservation,  and  near  Rice 
in  the  White  Mountains  Apache  Indian  Reservation.  In  the 
former  district  the  peridot  is  plentiful,  and  is  found  associated  with 
volcanic  rocks.  These  are  monzonite  porphyry,  orthoclase  basalt, 
and  peridotite  agglomerate.  The  peridot,  which  appears  to  have 
been  derived  from  the  agglomerate,  is  found  in  the  soil,  and  asso- 
ciated with  it  are  such  minerals  as  garnet,  diopside,  quartz,  calcite, 
titanic  iron,  etc.  Gems  of  1  to  2  carats'  weight  are  fairly  abundant, 
and  some  of  3  to  4  carats  are  found.  Those  of  dark  yellowish-green 
color  are  commonest. 

In  the  Rice  district  peridot  is  found  not  only  in  the  original 
basalt  rock  matrix,  but  also  loose  in  the  soil. 

Ruby.  —  A  red,  transparent  variety  of  corundum  (A1203),  having 
a  hardness  of  9  and  a  specific  gravity  of  4.  The  most  valuable  color 
in  ruby  is  a  deep,  clear,  carmine  red.  Rubies  of  large  size  are 

1  Merriam,  Science,  n.  s.f  XXVI:  380,  1907,  and  Sterrett,  U.  S.  Geol.  Surv., 
Min.  Res.,  1913,  p.  677. 


MINOR  MINERALS  385 

scarce,  so  that  a  3-carat  stone  of  good  color  and  flawless  is  worth 
several  times  as  much  as  a  diamond  of  the  same  size.  The  best 
ones  come  from  Burma.  In  the  United  States  they  have  been 
found  in  the  stream  gravels  of  Macon  County,  North  Carolina,  but 
the  production  is  not  a  steady  one.  Those  found  in  Arizona  and 
other  western  states  are  not  true  rubies,  but  a  variety  of  garnet 
(4,  12,  15). 

Sapphire  is  a  blue,  transparent  variety  of  corundum  (A12O3) .  It 
is  of  slightly  greater  hardness  and  specific  gravity  than  the  ruby, 
though  of  similar  composition.  Sapphires  of  good  color  and  size 
are  more  common  than  rubies  and  cheaper.  The  best  sapphires 
come  from  Siam.  In  the  United  States  they  have  been  found  in 
the  gravels  of  Cowee  County,  North  Carolina,  but  Yogo  Gulch, 
Montana,  is  now  the  main  source  of  domestic  supply.  They  range 
in  weight  from  under  1  up  to  4  or  5  carats  (4,  12,  18). 

The  Montana  sapphires  were  first  found  in  gravel  bars  on  the 
Missouri  River,  but  subsequently  they  were  discovered  in  dikes 
of  basic  igneous  rock  cutting  Carboniferous  (?)  limestone  in  south- 
western Fergus  County.  The  rock  is  of  somewhat  basic  character 
belonging  to  a  type  known  as  monchiquite,  and  the  sapphires  are 
obtained  from  the  somewhat  decomposed  portions  of  the  dike. 

There  are  two  companies,  both  operating  on  the  same  dike,  which 
has  a  width  of  10  to  20  feet,  and  has  been  traced  for  a  distance  of 
5  to  6  miles. 

Spodumene.  —  A  remarkable  transparent  lilac-colored  and  pale 
pink  to  white  spodumene,  known  as  Kunzite  (14)  has  been  found  in 
California  not  far  from  the  rubellite  locality,  and  occurring  in  a 
pegmatite  dike,  where  it  is  closely  associated  with  gem  tourmalines. 

Topaz.  —  This  is  a  fluosilicate  of  alumina,  crystallizing  in  the 
orthorhombic  system,  with  a  hardness  of  8,  specific  gravity  of  3.5, 
vitreous  luster,  and  yellow,  green,  blue,  red,  or  colorless.  It  occurs 
in  gneiss  or  granite,  as  well  as  in  other  metamorphic  or  igneous  rocks, 
and  is  associated  with  beryl,  mica,  tourmaline,  etc.  It  is  also  found 
in  alluvial  deposits.  The  best  gem  stones  come  from  Ceylon,  the 
Urals,  and  Brazil.  In  the  United  States  they  have  been  found  in 
small  quantities  in  Maine,  Colorado,  California  (12),  and  Utah. 

In  Utah  topaz  (17)  is  found  in  the  Thomas  range  of  mountains  about 
40  miles  north  of  Sevier  Lake,  at  a  locality  known  as  Topaz  Mountain.  The 
transparent  crystals  occur  in  lithophysse  in  rhyolite,  and  vary  from  color- 
less to  wine  color.  Rough  opaque  crystals  are  scattered  through  the  solid 
rhyolite.  The  crystals  are  believed  to  have  been  formed  by  vapors  or  solu- 


386  ECONOMIC  GEOLOGY 

tions  contemporaneous  or  nearly  so  with  the  final  consolidation  of  the  rock. 
In  the  weathering  of  the  rock  the  crystals  fall  out  and  become  mixed  with 
the  soil,  the  colored  ones  fading  on  exposure  to  the  light. 

Topaz  is  obtained  from  pegmatite  veins  near  Ramona,  San  Diego  County, 
where  it  occurs  in  pockets  in  albite  and  orthoclase.  The  topazes  are  white, 
yellow,  sea-green,  and  sky-blue,  some  of  them  being  of  large  size  (14). 

Tourmaline.  —  This  is  a  complex  silicate,  of  aluminum  and 
boron,  with  usually  varying  amounts  of  iron,  magnesium,  alkalies, 
and  water.  It  has  a  hardness  of  7  to  7.5  and  a  specific  gravity  of 
2.98  to  3.20.  The  color  is  variable,  and  this  variation  may  exist  in 
the  same  crystal. 

The  opaque,  black,  or  brown  tourmaline  is  a  somewhat  common 
mineral  in  many  metamorphic  rocks,  as  well  as  in  granite  and  other 
eruptive  rocks,  but  this  variety  has  no  value  as  a  gem. 

Gem  tourmalines  are,  however,  rather  rare,  being  known  in  Brazil, 
Russia,  and  Ceylon,  and  in  this  country  in  the  states  of  Maine, 
Connecticut,  and  California.  Of  the  gem  tourmalines  the  red  ones 
are  most  highly  prized,  especially  the  darker  ones;  the  green  ones 
are  usually  dark  green. 

A  large  number  of  green  tourmalines  have  been  obtained  from  a 
pegmatite  granite  at  Paris,  Maine,  and  many  are  found  in  a  belt  ex- 
tending from  Auburn  to  Newry  (23).  The  gems  here  are  likewise 
found  in  pegmatite,  and  are  associated  with  beryl. 

An  interesting  and  important  occurrence  of  red  tourmaline 
(rubellite)  has  been  worked  at  Pala,  San  Diego  County,  California. 
The  crystals  here  form  radiating  groups  in  lepidolite  and  the  earlier 
discovered  ones  were  clear  enough  for  cutting.  Valuable  crystals, 
many  of  gem  character,  have  since  been  found  in  pegmatite  veins 
near  Pala,  and  near  Mesa  Grande  (14). 

Turquoise  is  a  massive  hydrated  aluminum  copper  phosphate, 
of  waxy  luster,  blue  to  green  color,  and  opaque.  Its  hardness  is  6, 
and  specific  gravity  2.75.  It  usually  occurs  in  streaks  and  patches 
in  volcanic  rocks.  The  best  varieties  are  obtained  from  Persia, 
but  it  is  also  obtained  from  Asia  Minor,  Turkestan,  and  Siberia. 
In  the  United  States  turquoises  are  found  in  the  Los  Cerillos 
Mountains  near  Santa  Fe,  New  Mexico,  and  Turquoise  Mountain, 
Arizona,  as  well  as  in  Colorado. 

It  is  interesting  to  note  that  turquoise  was  hardly  known  in  the 
United  States  in  1890,  but  now  a  considerable  supply  comes 
from  the  southwestern  states  and  territories  (16«,  22,  25). 

The  production  of  turquoise  in  the  United  States  has  at  dif- 


MINOR  MINERALS  387 

ferent  times  come  from  New  Mexico,  Nevada,  Arizona,  California, 
and  Colorado. 

Turquoise  mines  have  been  operated  in  the  Burro  Mountains, 
15  miles  southwest  of  Silver  City,  New  Mexico.  The  country 
rock  of  granite,  which  is  cut  by  andesite-porphyry,  andesite,  and 
dacite,  is  much  altered,  and  the  turquoise  is  found  in  a  vein  or 
fissured  zone,  which  contains  kaolinized  feldspar  and  secondary 
quartz. 

In  this  strip,  which  is  40  to  60  feet  wide,  the  turquoise  occurs  as 
veins  and  nuggets,  the  former  filling  cracks  in  the  granite  -j1^  to  | 
inches  wide,  and  the  latter  in  the  kaolin.  The  veinlets  often  cross 
and  indicate  successive  periods  of  deposition. 

A  diversity  of  opinion  exists  regarding  the  origin  of  the  turquoise. 
Silliman  (Amer.  Jour.  Sci.,  1881,  July,  p.  67)  believes  it  to  have 
been  formed  by  heated  water  and  vapors,  which  destroyed  the  orig- 
inal character  of  the  rock  and  produced  new  compounds.  Clarke 
and  Diller  suggested  that  the  turquoise  represents  a  replacement  of 
the  apatite  of  the  granite.  Johnson  (16  a)  advanced  the  theory 
that  gases  played  a  role  in  the  decomposition  of  the  rock,  and  called 
attention  to  the  association  of  fluorite  with  the  turquoise.  The 
alumina  of  the  turquoise,  he  thinks,  was  derived  from  the  feldspar, 
the  phosphorus  from  the  apatite,  and  the  copper  from  cupriferous 
solutions  which  formed  the  ores  in  that  region. 

Zalinski  (25)  believes  that  hot  solutions,  coming  from  below, 
caused  a  kaolinization  of  the  granite,  the  silica  set  free  in  this  connec- 
tion being  deposited  in  cracks  and  fractures  with  the  turquoise. 
Solutions  carrying  aluminum  phosphate  rose  along  fissures  parallel 
with  the  walls,  while  the  copper  solutions  came  along  an  intersect- 
ing series.  Intermingling  of  the  two  solutions  formed  the  turquoise. 

In  Mohave  County,  Arizona  (22),  the  turquoise  is  found  in  the 
younger  intrusive  porphyries  and  granite,  both  of  which  have  been 
more  or  less  altered,  especially  around  the  turquoise  deposits. 
This  alteration  consists  of  kaolinization,  but  there  has  also  been 
some  silicification,  as  shown  by  a  deposition  of  quartz  in  joints  and 
between  the  grains.  Some  of  the  turquoise  seems  to  have  been 
derived  from  the  kaolin  by  the  addition  of  phosphoric  acid  and 
copper,  but  much  of  it  has  been  deposited  from  solution,  as  it  occurs 
as  seams  and  veinlets,  as  well  as  in  patches  or  streaks  in  quartz 
seams  and  veinlets.  The  nodular  turquoise  is  less  common. 

The  Colorado  turquoise  deposits  are  associated  with  trachyte, 
but  they  show  relations  similar  to  the  Arizona  material. 


388 


ECONOMIC  GEOLOGY 


In  the  district  of  northeastern  San  Bernardino  County,  Cali- 
fornia, where  several  large  mines  have  been  operated,  the  tur- 
quoise occurs  in  a  coarse  porphyritic  granite,  and  a  monzonitic  (?) 
porphyry.  These  have  been  fractured,  and  then  sericitized  and 
kaolinized,  as  well  as  stained  with  limonite.  Later  solutions 
carrying  the  elements  of  turquoise  passed  through  the  same 
fissures  where  kaolinization  occurred  and  deposited  the  turquoise 
in  seams  and  veinlets,  as  well  as  in  nodular  masses  in  the  kaolin- 
ized and  sericitized  rock.1 

Variscite.  —  This  mineral  alone  is  not  used  as  a  gem  stone, 
but  it  is  cut  with  its  associated  matrix.  This  mixture,  which  is 
sometimes  called  amatrice  (26),  is  composed  of  variscite,  wardite, 
and  probably  other  associated  minerals  such  as  chalcedony  and 
quartz.  The  first  two  are  hydrous  phosphates  of  aluminum, 
showing  varying  shades  of  green,  of  compact,  tough  character 
and  having  a  hardness  of  4  and  5  respectively.  The  matrix 
consists  of  chalcedony  and  quartz  with  other  minerals,  among 
them  yellowish  gray  and  white  phosphates.  The  decorative 
value  of  the  material  lies  in  the  variety  and  arrangement  of  its 
colors. 

Production  of  Precious  Stones.  —  The  United  States  produces 
a  number  of  different  kinds  of  gems  and  precious  stones,  but  the 
total  output  is  by  no  means  large.  Moreover,  those  kinds  most 
used  are  produced  in  but  small  amounts.  The  collection  of  ac- 
curate statistics  of  production  is,  for  several  reasons,  quite  difficult 
and  therefore  the  output  has  to  be  estimated  in  some  cases.  The 
figures  of  production  for  1912  to  1914  are  given  on  the  opposite 
page. 

The  imports  of  precious  stones  into  the  United  States  for  1909  to 
1914  as  reported  by  the  Bureau  of  Statistics  is  given  below. 


IMPORTS  OF  PRECIOUS  STONES  INTO  THE  UNITED  STATES,  1909-1914  2 


YEAR 

VALUE 

YEAR 

VALUE 

1909  
1910  

$40,237,509 
40,704,487 

1912  
1913  

$11,  363,325 
45,431,998 

1911        

40,820,430 

1914 

18  711  084 

1  U.  S.  Geol.  Surv.,  Min.  Res.,  1913,  p.  695. 

2  These  figures  include  pearls. 


MINOR  MINERALS  389 

PRODUCTION  OF  PRECIOUS  STONES  IN  THE  UNITED  STATES  IN  1912-1914 


1912 

1913 

1914 

Agates,  chalcedony,  onyx,  etc.    . 

$9,978 
363 

$8,895 
389 

$8,312 
265 

Benitoite                    

150 

Beryl,  aquamarine,  blue,  pink,  yellow,  etc. 
Californite  

1,765 
275 

1,615 
152 

2,395 
1  425 

Chlorastrolite  .     .••/... 

350 

Copper  ore  gems,  chrysocolla,  malachite, 

1,085 

2,350 

1  280 

Chrysoprase     

220 

75 

Cyanite             .     

10 

^,475 

16,315 

765 

Emerald 

2  375 

Epidote                       .          .          .     .     . 

10 

Feldspar,  amazon  stone,  sunstone,  etc. 
Garnet,  almandine,  pyrope,  hyacinth,  etc. 
Gold  ouartz                     

1,310 
860 
1  900 

1,285 

4,285 
300 

449 
1,760 
1  050 

300 

Jasper,  petrified  wood,  bloodstone,  etc. 
Opal                                                       .     . 

6,005 
1W  925 

5,275 
115  130 

4,700 
1  114 

Peridot    

8,100 

375 

100 

Prase                      .          

25 

Pyrite      

265 

50 

_ 

Quartz,  rock  crystal,  smoky  quartz,  rutil- 
ated  quartz   etc     

2448 

1  640 

4046 

865 

337 

400 

550 

165 

1  050 

Ruby                           '. 

2260 

200 

100 

^95,505 

238,635 

60,392 

650 

50 

50 

Spodumene,  kunzite,  hiddenite   .     .     . 
Thomsonite                                          .     • 

18,000 
450 

6,520 

4,000 
21 

Topaz           

375 

736 

1,380 

Tourmaline             >          ...... 

a28,200 

7,630 

7980 

Turquoise  matrix 

10  140 

8075 

13370 

Variscite,  amatrice,  chlorutahlite,  utahlite 
Miscellaneous  gems        

^,450 
4,408 

^,105 
2,920 

5,055 

2287 

$319,722 

$319,454 

$124,651 

1  Estimated  or  partly  so. 


390  ECONOMIC  GEOLOGY 


REFERENCES    ON    PRECIOUS    STONES 

GENERAL  WORKS.  1.  Bauer,  Edelsteinkunde.  (Leipzig,  1896.  Transla- 
tion by  L.  J.  Spencer,  London.)  2.  Farrington,  Gems  and  Gem, 
Minerals.  (Chicago,  1903.)  3.  Goodchild,  Precious  Stones.  (N.  Y.. 
1908.)  4.  Kunz,  Gems  and  Precious  Stones  of  North  America.  (N) 
Y.,  1892.)  5.  Streeter,  Precious  Stones  and  Gems.  (London,  1892.. 
5a.  Stutzer,  Die  Nicht-Erze,  Berlin,  1911.  (Diamond,  general.)  56 
Boise,  Min.  Mag.,  XII:  329,  1915.  (German  S.  W.  Africa.) 

SPECIAL  PAPERS.  6.  Baskerville,  Science,  n.  s.,  XVIII:  303,  1903.  (Kunz- 
ite.)  7.  Blatchley,  Ind.  Dept.  Geol.  Nat.  Res.,  XXVII:  11.  (Dia- 
monds in  drift,  fnd.)  7a  Camsell,  Econ.  Geol.,  VI:  604,  1911.  (Dia- 
monds, Brit.  Col.)  8.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  491:  306, 

1911.  (Diamond  genesis.)     9.  Derby,    Jour.    Geol.,  XIX:    627,   1911. 
(Origin   Brazil  diamonds.)     10.  Hobbs,   Jour.   Geol.,   VII:  .375,    1899. 
(Wis.    diamonds.)     11.  Kunz.,    L'.    S.    Geol.    Surv.,    Min.    Res.,    1905: 
1249,    1906.     (Opal,    Ore.)     12.  Louderback,    Univ.    Calif.    Pub.,    V, 
No.   23:    331,   1909.     (Benitoite.)     13.  Kunz   and  Washington,   Amer. 
Inst.    Min.    Engrs.,    Trans.    XXXIX:     169,    1908.     (Ark.    diamonds.) 
14.  Kunz,  Cal.   State   Min.   Bur.,  Bull.   37,    1905.     (Calif,    gems   and 
ornamental   stones.)     15.  Kunz,   N.   Ca.   Geol.  Surv.,   Bull.   12,   1907. 
(History   N.  Ca.  industry.)     16.     Kunz,  Amer.  Jour.  Sci.,   IV:    417, 
1897.     (Mont,  sapphire.)     16a.  Johnson,  Sch.  of  Mines  Quart.,  XXIV: 
493,  1903.     (N.  Mex.,  Turquoise.)     166.  MacFarlane,  Eng.  and  Min. 
Jour.,  Oct.  28,   1911.     (Opals,   Mex.)     16c.  Miser,  U.  S.  Geol.  Surv., 
Bull.    540:     534,    1914.     (Ark.)     16d.  Paige,    Econ.    Geol.    VII:     382. 

1912.  (Turquoise,  Burro  Mts.,  N.  M.)     17.  Patton,  Geol.  Soc.  Amer., 
Bull.  XIX:    177,   1908.     (Topaz,   Utah.)     17a.  Penrose,   Econ.   Geol., 
II:    275,   1907.     (Premier  diamond    mine.)     18.  Pirsson,  Amer.  Jour. 
Sci.,  IV:  421,1897.     (Petrography  Montana  sapphire  rock.)    18o.  Pogue, 
Nat.  Acad.  Sci.,  XII,  Pt.  Ill,  1915.     (Turquoise.)     19.  Pratt,  U.  S.  Geol. 
Surv.,   Bui.  269,   1906.       (Sapphire.)       20.  Pratt  and  Lewis,   N.  Ca.' 
Geol.  Surv.,  I:     180,   1905.     (Ruby.)     21.  Purdue,  Econ.   Geol.,  Ill: 
525,  1908.      (Ark.  diamonds.)     22.  Sterrett,  U.  S.  Geol.  Surv.,  1908. 
Chapter  on   Precious   Stones.       (Moss  agate,   WTyo.;     Peridot,   Ariz.; 
Garnet,    Ariz.;    Turquoise,    Ariz,    and    Colo.;    Variscite,    Utah.)     23. 
Wade,  Eng.  and  Mm.  Jour.,  June  5.  1909.     (Tourmaline  and  Beryl, 
Me.}     24.  Watson,  Min.  Res.  Va.,  1907:  386.     (Amethyst,  Va.)     24a. 
Williams,  G.  F.,  Diamond  Mines  of  South  Africa  (London,  1902.)     25. 
Zalinski,  Econ.  Geol.,  II:  464,  1907.       (Turquoise,  N.  Mex.)     26.  Za- 
linski,  Eng.  and  Min.  Jour.,  May  22,  1909.     (Utah  Amatrice.) 


QUARTZ 

Although  this  material  has  been  briefly  referred  to  under  abra- 
sives and  glass  sands,  it  is  sufficiently  important  to  require  treat- 
ment as  a  special  topic.  . 


MINOR  MINERALS  391 

Silicon  is  the  second  most  abundant  constituent  of  the  earth's 
crust,  and  quartz,  of  which  it  is  an  important  ingredient,  is  the 
most  abundant  of  all  minerals,  but  varies  greatly  in  its  mode  of 
occurrence  and  uses.  Thus  some  varieties,  such  as  rose  or  smoky 
quartz,  amethyst,  etc.,  are  used  as  gems.  Quartz  in  the  form  of 
sand  is  employed  for  molding  (p.  335),  building,  glass-making 
(p.  340),  and  pottery  manufacture,  etc.  In  the  form  of  sandstone 
and  quartzite  (p.  156)  it  is  of  value  as  a  structural  material. 

The  forms  of  quartz  considered  here  are  the  massive  crystalline 
quartz  (often  known  as  vein  quartz),  flint,  and  quartzite  used  for 
purposes  other  than  building  or  paving. 

Vein  Quartz  (1-3) .  —  This  form  of  quartz,  which  is  white,  or  less 
often  rose  or  smoky,  occurs  in  veins  or  dike-like  masses,  usually  in 
metamorphic  rocks.  It  may  be  of  high  purity,  or  may  be  mixed 
with  feldspar,  mica,  etc.,  as  an  ingredient  of  pegmatite,  in  which  case 
it  is  obtained  as  a  by-product  in  the  mining  of  feldspar.  Vein 
quartz  is  produced  in  Connecticut,  New  York,  Pennsylvania,  and 
Maryland.  A  crystalline  quartz,  not  of  vein  character,  obtained  in 
southern  Illinois  is  referred  to  under  Tripoli  (p.  412). 

Quartzite.  —  This  rock  is  quarried  at  a  few  localities  for  special 
purposes.  Thus  in  Cherokee  County,  North  Carolina,  a  vitreous 
Cambrian  quartzite  has  been  quarried  for  use  as  a  flux  in  copper 
smelting.  Large  quantities  of  a  hard  brittle  quartzite  have  also 
been  quarried  near  Wausau,  Marathon  County,  Wisconsin,  the 
ground  product  being  used  for  sandpaper  and  other  abrasive  pur- 
poses, filters,  bird  grit,  wood  filler,  etc.  It  analyzes  99.07  per  cent 
silica. 

Flint  or  Chert.  —  This  term  is  applied  to  lusterless  quartz  of  very 
compact  texture  and  conchoidal  fracture,  which  often  forms 
nodules  in  limestone  or  chalk.  In  some  cases  these  concretions 
may  represent  silicified  fossils.  Flint  nodules  are  found  in  many 
formations  in  the  United  States,  but  little  of  the  domestic  mate- 
rial has  been  utilized  except  for  road  metal.  The  entire  supply  of 
true  flint  demanded  by  this  country  for  special  purposes  is  obtained 
from  France,  England,  Norway,  and  even  Greenland,  being  brought 
over  as  ballast.  The  smaller  nodules  are  used  in  tube  mills,  but 
much  of  the  supply  is  calcined  to  whiteness  and  then  ground  for  use 
in  pottery  manufacture. 

Uses  of  Quartz.  —  Quartz  is  extensively  used  in  pottery  manu- 
facture to  diminish  the  shrinkage  of  the  ware  in  burning,  and  for  this 
purpose  it  should  have  under  1  per  cent  of  iron  oxide.  In  recent 


392 


ECONOMIC   GEOLOGY 


years  quartzite  and  sandstone  have  been  more  used  than  vein 
quartz.  It  is  also  employed  in  the  manufacture  of  wood  filler, 
paints,  scouring  soaps,  sandpaper,  filters,  and  tooth  powders. 
Blocks  of  massive  quartz  and  quartzite  are  employed  as  a  filter  for 
acid  towers.  Quartz  is  also  used  as  a  flux  in  copper  smelting  and 
in  the  manufacture  of  silicon  and  ferrosilicon.  Much  chemical 
ware  is  now  made  of  fused  quartz. 

PRODUCTION  OF  QUARTZ   IN  THE   UNITED   STATES,    1909-1913,   IN  SHORT 

TONS 


YEAR 

CRUDE 

GROUND 

TOTAL 

Quantity 

Value 

Quantity 

Value 

Quantity 

Value 

1909 
1910 
1911 
1912 
1913 
1914 

121,459 
49,886 
77,759 
82,205 
74,176 
123,508 

$131,334 
80,984 
70,430 
67,256 
54,442 
88,820 

14,010 
13,691 
10,184 
15,669 
23,726 
29,893 

$118,132 
112,773 
84,692 
124,429 
147,046 
271,682 

135,469 
63,577 
87,943 
97,874 
97,902 
153,401 

$249,466 
193,757 
155,122 
191,685 
201,488 
360,502 

PRODUCTION  OF  QUARTZ  IN  CANADA,  1912-1914 


YEAR 

SHORT  TONS 

VALUE 

1912    .... 
1913    .... 
1914   .... 

100,242 
78,261 
54,148 

$195,216 
169,842 
83,583 

The  imports  of  flint  and  flint  stones  in  1914  were  valued  at  $479,146  (un- 
ground).  Pure  crystalline  quartz,  for  pottery,  paint,  and  wood  filler  brings 
about  $2  to  $3.50  per  long  ton,  crude,  f  .o.b.  quarries,  while  the  ground  prod- 
uct sells  for  $6.50  to  $10  per  short  ton  f.o.b.  mills.  Quartzite  for  sandpapers 
sells  for  $1  to  $2  per  long  ton  f.o.b.  mines,  and  $6  to  $8  ground,  f.o.b. 
mills.  The  finest  ground  quartz  for  tooth  powders  sells  for  as  high  as  $20 
per  ton.  Imported  French  flints  are  quoted  at  $3.50  to  $4  per  long  ton 
f.o.b.  Philadelphia. 

REFERENCES  ON  QUARTZ 

1.  Bastin,  U.  S.  Geol.  Surv.,  Min.  Res.  for  1907.  (General  and  U.  S.) 
2.  Bastin,  U.  S.  Geol.  Surv.,  BuU.  315  :  294,  1907.  (N.  Y.)  3.  Rice 
and  Gregory,  Conn.  Geol.  Surv.,  Bull.  6  :  136,  1906.  (Conn.) 


STRONTIUM 

Sources  and  Occurrence.  —  The  two  minerals  serving  as  sources 
of  strontium  salts  are  celestite  (SrSO4)  and  strontianite  (SrCO3). 


MINOR  MINERALS  393 

Of  these  two  the  former  is  the  more  important,  but  the  latter  is  the 
more  valuable,  as  the  strontium  salts  can  be  more  easily  extracted 
from  it. 

Both  celestite  and  strontianite  have  been  found  at  a  number  of 
localities  in  the  United  States,  but  seldom  in  large  quantities.  One 
important  deposit  of  celestite  has  been  found  in  limestone  caves  near 
Put-in  Bay,  Strontian  Island,  in  Lake  Erie,  and  in  opening  up  the 
cave  150  tons  of  the  mineral  were  taken  out.  Similar  occurrences 
have  been  found  in  limestones  in  other  states,  but  none  of  them 
have  any  commercial  value. 

Nearly  all  the  strontium  salts  now  used  in  the  United  States  are 
imported  from  Germany,  the  crude  material  being  obtained  in  part 
from  Westphalia,  Germany,  and  also  from  Thuringia,  Germany, 
and  Sicily. 

Uses. —  Strontium  salts  are  used  in  sugar  refining,  in  fireworks 
manufacture,  and  to  a  small  extent  in  medicine. 

REFERENCE  ON  STRONTIUM 

1.  Pratt,  U.  S.  Geol.  Surv.,  Min.  Res.,  1901:  955,  1902. 

SULPHUR  AND  PYRITE 

These  two  minerals  are  discussed  in  the  same  chapter  because 
both  serve  as  sources  of  sulphur  or  sulphuric  acid. 

SULPHUR 

Native  sulphur  may  be  formed  in  several  different  ways  as  follows : 

Solfataric  Type.  —  Sulphur  is  often  found  in  fissures  of  lava  and 
tuff  around  many  active  and  also  extinct  volcanic  vents.1  When 
thus  formed  as  a  volcanic  sublimate  it  may  be  a  product  of  reactions 
between  sulphur  dioxide  and  hydrogen  sulphide.  It  may  also  be 
formed  by  incomplete  combustion  of  hydrogen  sulphide,  probably 
as  follows:  2  H2S  +  02  =  2  H20  +  2  S.  This  latter  change  prob- 
ably occurs  at  least  a  short  distance  below  the  surface,  where  oxygen 
is  deficient,  as  at  the  surface  the  H2S  may  form  H2S04. 

Deposits  of  the  solfataric  type  are  rarely  of  commercial  impor- 
tance, but  they  are  worked  in  Japan,  and  have  also  been  worked  in 
the  crater  of  Popocatepetl  in  Mexico. 

Mineral  Spring  Deposits.  —  Sulphur  is  not  an  uncommon  de- 
posit around  mineral  springs,  its  deposition  being  due  to  imperfect 

1  Ferric  chloride  is  sometimes  deposited  around  fumarolic  vents,  and  might,  owing 
to  its  similar  color,  be  at  first  mistaken  for  sulphur. 


394  ECONOMIC   GEOLOGY 

oxidation  of  hydrogen  sulphide,  the  sulphur  appearing  in  the 
spring  waters  as  a  whitish  powder.  It  has  been  noticed,  however, 
that  the  associates  of  this  type  of  sulphur  deposit  are  often  some 
form  of  lime  carbonate,  or  gypsum,  and  that  the  sulphur  de- 
positing springs  sometimes  rise  through  fissures  in  limestone,  lead- 
ing to  the  belief  that  a  reaction  like  the  following  may  occur:  —  l 


The  calcium  hydrosulphide  formed  will  yield  calcium  carbonate 
or  gypsum  on  the  escape  of  the  H2S  as  follows  :  — 

Ca(SH)2+2O2+2H2O  =  CaSO4-2H2O+H2S; 
Ca(SH)2+C02+H20  =  CaCO3+H2S. 

This  accounts  for  the  travertine  and  gypsum  found  with  some 
mineral  spring  deposits  (p.  397).  It  is  possible  also  that  some  of 
the  sulphur  is  deposited  by  sulphur  bacteria.2  These  have  the 
power  of  oxidizing  H2S  to  H^SCU,  and  retaining  free  sulphur 
in  their  cells,  if  there  is  an  excess  of  H^S.  The  H2SO4  formed 
will  in  turn  attack  calcium  bicarbonate,  which  the  cell  takes  up 
from  the  water  and  converts  it  into  calcium  sulphate.  Sulphur 
under  favorable  conditions  may  also  be  carried  in  the  colloidal 
form,  and  be  later  precipitated.3 

Gypsum  Type  (3e,  80)  .  —  This  type,  which  is  of  world-wide 
distribution,  is  so  called  because  of  its  constant  association  with 
with  gypsum.  Limestone,  marls,  and  bituminous  matter  are 
also  found  with  it.  The  Sicilian  and  Louisiana  deposits  are  well- 
known  members  of  this  group,  and  are  referred  to  on  pages  398  and 
396.  Because  of  its  lack  of  association  with  volcanic  activity 
and  close  relationship  to  sedimentary  formations,  the  true  explan- 
ation of  its  origin  has  been  somewhat  difficult  to  find.  Most  of 
the  theories  have  been  advanced  in  connection  with  a  study  of 
the  Sicilian  deposits,  and  may  be  briefly  stated  as  follows  :  — 

1.  The  sulphur  is  thought  to  have  been  formed  by  the  reducing 
action  of  bituminous  matter  on  gypsum  according  to  the  following 
reactions  :  — 

1  Bechamp,  Ann.  chim.  phys.,  4th  ser.,  XVI:   234,  1869. 

2  Winogradsky,  Botan.  Zeit.,  XLV,  No.  31-37,  1887. 

3Raffo  and  Marncini,  Zeitschr.  Chemie  Ind.  Kolloide,  IX:    58,  1911. 


MINOR   MINERALS  395 

CaSO4  +  2C  =  CaS  +  2CO2  ; 


=  H2O+S. 

This  theory  was  first  suggested  by  G.  Bischof,1  and  is  still  held 
by  many. 

2.  Stutzer  (8a)    has  suggested  that  the  sulphur  is  of  purely 
sedimentary  origin.     He  bases  his  belief  on:    (a)  Its  stratified 
structure;    (6)  the  interstratification  with  limestone,  and  in  the 
Sicilian  deposits  at  least,  its  absence  in  the  gypsum;  and  (c)  the 
presence  of  interbedded  clay  layers,  which  would  prevent  circula- 
tion, and  preclude  the  deposition  of  the  sulphur  by  permeating 
waters. 

In  accordance  with  this  view  he  assumes  that  decaying  organ- 
isms in  the  water  yielded  hydrogen  sulphide,  or  that  it  might 
have  been  formed  by  the  action  of  hydrocarbons  on  calcium  sul- 
phate. The  oxidation  of  the  hydrogen  sulphide  was  brought 
about  either  by  the  oxygen  of  the  air,  or  by  sulphur  bacteria 
(p.  394). 

3.  A  third  theory  is  that  the  hydrogen  sulphide  was  supplied 
by  cold  springs  discharging  into    fresh-water  lakes,2  or  by  hot 
springs  flowing  out  over  the  ocean  floor.3 

4.  Hunt  (3a),  after  noting  that  the  sulphur  of  Sicily  forms  basin- 
like  deposits,  underlying  the  more  continuous  gypsum  which  con- 
tains occasionally  lens-shaped  masses  of  secondary  sulphur,  sug- 
gests the  following:  — 

The  sulphur  was  collected  in  small  basins,  whose  water  had  a 
comparatively  high  average  temperature,  and  a  high  sulphate 
content.  Bacterial  reactions  extending  over  a  period  of  years 
caused  a  copious  production  of  H2S  from  decomposition  of  sul- 
phates, and  reactions  similar  to  those  mentioned  under  Mineral 
Spring  Deposits  (p.  393),  might  cause  a  simultaneous  precipita- 
tion of  sulphur  and  calcium  carbonate.  Some  of  the  sulphur 
would,  however,  be  absorbed  by  the  Ca(SH)2,  forming  an  unstable 
poly  sulphide,  which  would  yield  copious  precipitations  of  free 
sulphur  from  time  to  time.  Continued  evaporation  of  the  basin 
waters  eventually  rendered  them  so  saline  as  to  check  bacterial 
action  and  also  precipitate  the  overlying  gypsum. 

1  Chem.  u.  Phys.  Geol.  II:    144,  1851. 

2  A.  von  Lasaulx,  Neues  Jahr.  Min.,  1879,  p.  490. 

3  G.  Spezia,  Neues  Jahrb.  Min.  1893,,  I:   38. 


396  ECONOMIC  GEOLOGY 

5.  In  the  case  of  the  Louisiana  deposits  at  least,  Harris  has 
suggested  ascending  hot  waters  as  the  source  of  the  sulphur. 

Metallic  Sulphide  Type  (4).  Sulphur  may  result  from  alteration  of  pyrite, 
marcasite,  or  related  sulphides,  possibly  through  action  of  bituminous  matter. 
Gypsum  is  a  common  associate.  No  deposits  of  economic  value  have  been 
formed  in  this  manner. 

Distribution  of  Sulphur  in  the  United  States.  —  Louisiana  and 
Texas  are  the  most  important  producers,  smaller  quantities  coming 
from  other  western  states,  especially  Wyoming. 

Louisiana  (4,  5, 10).  —  The  deposits  of  sulphur  found  in  this  state 
are  the  most  important  domestic  source  of  this  material.  They 
occur  in  Calcasieu  Parish,  and  were  discovered  as  early  as  1868  in 
boring  for  oil  and  gas  at  the  head  of  Bayou  Choupique,  15  mile? 
west  of  Lake  Charles. 

The  bed  of  sulphur,  which  is  of  Cretaceous  age  (Harris  and 
Veatch),  lies  300  to  400  feet  below  the  surface,  is  over  100  feet 
thick,  and  is  underlain  by  gypsum  and  salt.  It  is  supposed  by 
some  to  have  been  derived  from  gypsum,  but  Harris  suggests  the 
possibility  of  its  precipitation  from  ascending  hot  waters  (see 
under  Salt,  p.  210). 

Owing  to  the  quicksand-like  character  of  the  overlying  beds, 
attempts  to  sink  a  shaft  to  the  deposit  were  unsuccessful.  It  is 
now  obtained  by  pumping  superheated  steam  down  through  pipes, 
melting  the  sulphur,  and  drawing  it  to  the  surface,  where  it  is 
discharged  into  vats  to  cool  and  solidify. 

A  similar  deposit  of  sulphur  is  found  near  Bryan  Heights, 
Brazoria  County,  Texas.  It  is  in  one  of  the  structural  domes  so 
characteristic  of  the  Mississippi  embayment  and  referred  to  under 
Oil  (p.  106). 

Utah  (6) .  —  Sulphur  of  the  solfataric  type  was  mined  at  Sul- 
phurdale  in  central  Utah  for  some  years.  In  this  district  there 
are  found  a  series  of  rhyolites  and  andesites,  overlain  in  places 
by  basalts,  the  whole  resting  probably  on  Paleozoic  sediments. 

The  sulphur,  which  occurs  in  a  soft  rhyolitic  tuff  (sometimes 
called  gypsum),  sometimes  forms  cylindrical  masses  or  cones  10 
to  15  feet  in  diameter,  and  with  a  rudely  radial  structure,  but 
most  of  it  is  found  as  a  dark-colored  impregnation  or  cementing 
substance  of  the  tuff. 

Occasionally  there  are  seen  branching  veins  of  nearly  pure  yellow 
sulphur,  with  a  banding  parallel  to  tke  walls,  and  these  may  repre- 


MINOR    MINERALS 


397 


H99JO  JOIO- 


o 


sent  fissure  fillings  from  solution,  since  acid  water  partly  filled  with 
yellow  sulphur  issues  from  the  fissures. 

The  crude  material  varies  greatly  llllpl 

in  richness,  some  showing  as  much 
as  80  per  cent  sulphur,  but  rock  run- 
ning as  low  as  15  per  cent  is  market- 
able. An  analysis  of  the  sulphur 
from  the  retorts  yielded:  S,  99.71; 
nonvolatile  matter  (SiC^,  Fe20s, 
etc.),  .23;  free  SOs,  tr.;  moisture 
at  100°  C.,  .06. 

A  volcanic  origin  is  suggested  for 
the  sulphur,  because  of  its  close 
association  with  volcanics,  and  the 
position  of  the  beds  along  a  fault 
line.  Gas  now  escapes  from  the 
deposits  in  large  volumes,  and  hy- 
drogen sulphide  boils  up  through 
water  standing  in  the  workings. 
The  sulphur  may  therefore  have 
been  precipitated  by  the  oxidation 
of  the  hydrogen  sulphide,  which  is 
presumably  of  volcanic  origin.  Oxi- 
dation of  the  sulphur  may  give  80s 
and  this  by  reaction  with  water, 
HoSO^.  Analysis  of  water  issuing 
from  the  beds  shows  sulphuric  acid. 

Wyoming.  —  Native  sulphur  has 
been  mined  in  Wyoming  near  Cody 
(12),  and  near  Thermopolis  (ll),  the 
mode  of  occurrence  at  the  two  local- 
ities being  almost  identical.  At  the 
latter  locality  the  deposits  are  found 
in  the  altered  Embar  (middle  Car- 
boniferous) limestone  which  imme- 
diately underlies  a  travertine  deposit 
(Fig.  125).  §!««* 

The  sulphur  occurs  in  small  yellow  I  ^ 

crystals  filling  veins  or  cavities  in 

the  rocks,  and  in  massive  form  as  a  replacement  of  calcium  carbonate 
by  sulphur,  the  original  structure  of  the  limestone  being  retained. 


^ 
*1 

o  pi 

|    fe 

O    ^' 

2  6 


e  .a 

!a 


g'5! 


398 


ECONOMIC   GEOLOGY 


The  distribution  of  the  sulphur  appears  to  be  very  irregular,  and 
confined  to  those  portions  of  the  limestone  surrounding  the  chan- 
nels of  the  hot  springs  that  deposited  the  travertine.  The  at- 
tempted explanation  of  the  origin  of  the  deposits  is  that  surface 


Silici  fled  limestone 


Sulphur  bearing  bed 


Gypsum  and  bituminous  marl 
gForaminiferous  marl 


FIG.  126.  —  Section  in   Sicilian  sulphur   deposits.     (After  Mottura,  from  Stutzer, 

Die  Nicht-Erze.) 

waters  worked  their  way  downward  along  the  sandstones  from  the 
Owl  Creek  Mountains  (Fig.  125),  and  came  into  contact  with  some 
uncooled  body  of  igneous  rock,  which  not  only  heated  them,  but 

also  supplied  them  with  hydrogen 
sulphide.  Following  this  they  passed 
upward  through  the  much-fractured 
beds  of  the  anticline  with  which  the 
deposits  are  associated.  As  these 
waters  approached  the  surface,  the 
sulphur  was  precipitated  by  oxida- 
tion, or  by  other  processes  mentioned 
under  Mineral  Springs  Deposits  (p. 
393).  Hot  springs  carrying  both 
H2S  and  C02  exist  there  at  pres- 
ent. 

The  depth  of  the  deposits  at  these 
two  localities  is  not  believed  to  be 
great,  but  in  the  rich  pockets  the 
sulphur  may  form  30  to  50  per  cent 
of  the  rock. 

Other  States.  —  Sulphur  deposits  have  been  worked  in  Colorado,  Nevada 
(1),  and  California  (2). 

Sicily  (3a,  8a).  —  In  the  Sicilian  sulphur-producing  region  ^he  sedimentaries 
include  (1)  Sands,  sandstones  and  shell  breccia  of  Upper  Pliocene;  (2)  Fora- 
miniferal  limestone  of  Lower  Pliocene;  and  (3)  Upper  Miocene  sulphur-bearing 


FIG.  127.  —  Banded  sulphur-bear- 
ing rocks  from  Sicily;  black, 
sulphur;  dotted,  limestone; 
white,  calcite.  (From  Stutzer, 
Die  Nicht-Erze.) 


MINOR  MINERALS 


399 


series,  consisting  of:  (a)  an  upper  gy spurn  member  with  occasional  lenses  of 
secondary  sulphur,  and  (6)  a  series  of  beds  of  sulphur-bearing  limestone,  sepa- 
rated from  each  other  by  bituminous,  salty  clays  and  shales.  The  individual 
sulphur  beds  may  vary  from  one  to  thirty  (exceptional)  meters  in  thick- 
ness. Associated  with  the  sulphur  are  celestite  and  calcite,  less  often  barite, 
also  bituminous  matter.  The  whole  series  has  been  disturbed  by  folding 
and  faulting. 

Uses  of  Sulphur.  —  The  most  important  use  of  sulphur  is  for 
the  manufacture  of  sulphuric  acid  and  in  paper  manufacture.  Some 
is  also  used  in  making  matches,  for  medicinal  purposes,  and  in 
making  gunpowder,  fireworks,  insecticides,  for  vulcanizing  india 
rubber,  etc. 

In  recent  years  pyrite  has  largely  replaced  sulphur  for  the  manu- 
facture of  sulphuric  acid,  and  the  increase  in  price  of  Sicilian  sulphur 
has  helped  this. 

The  greater  portion  of  the  world's  supply  of  sulphur  is  obtained 
from  Sicily,  the  United  States  consuming  the  largest  amount. 

Production  of  Sulphur.  —  The  sulphur  industry  of  the  United 
States  has  grown  rapidly  in  the  last  few  years,  and  in  1907,  for  the 
first  time  in  its  history,  the  value  of  the  importations  fell  below  the 
million  dollar  mark,  due  to  the  great  decline  in  the  imports  of  crude 
sulphur.  Louisiana  continues  to  be  a  great  producer,  and  the  com- 
petition of  the  product  from  this  state  with  imported  Sicilian  mate- 
rial has  reacted  somewhat  disastrously  on  the  latter. 

The  production  for  1909  to  1913  is  given  below. 

SULPHUR  IMPORTED  AND  ENTERED  FOR  CONSUMPTION  IN  THE  UNITED  STATES, 
1910-1914,  BY  KINDS,  IN  LONG  TONS 


YEAR 

CRUDE 

FLOWERS  OF 
SULPHUR 

REFINED 

ALL  OTHERS 

TOTAL 
VALUE 

Quan- 
tity 

Value 

Quan- 
tity 

Value 

Quan- 
tity 

Value 

Quan- 
tity 

Value 

1910 
1911 
1912 
1913 
1914 

28,656 
24,200 
26,885 
15,122 
23,610 

$496,073 
434,796 
494,778 
286,209 
398,984 

1024 
3891 
1311 
5899 
621 

$30,180 
83,491 
39,126 
115,574 
17,214 

1106 
985 
1665 
1234 
1800 

$25,869 
24,906 
40,933 
29,091 
47,568 

47 
68 
66 
350 
104 

$  6,489 
9,643 
9,137 
17,690 
14,171 

$558,611 
552,836 
583,974 
448,564 
477,937 

PRODUCTION  OF  SULPHUR  IN  THE  UNITED  STATES,  1910-1914 


YEAR 

LONG  TONS 

VALUE 

1910   . 
1911    .           .     . 
1912   .           .     . 
1913   .           .     . 
1914   . 

255,534 
265,664 
303,472 
311,590 
327,634 

$4,605,112 
4,787,049 
5,256,422 
5,479,849 
5,954,236 

400  ECONOMIC  GEOLOGY 

The  imports  came  mainly  from  Italy  and  Japan.  The  exports 
in  1914  amounted  to  98,153  long  tons,  valued  at  $1,807,334,  this 
being  72,018  long  tons  in  excess  of  the  import.  These  figures 
indicate  that  the  country  is  producing  more  than  enough  sulphur 
to  supply  its  own  needs. 

REFERENCES    ON    SULPHUR 

1.  Adams,  U.  S.  Geol.  Surv.,  Bull.  225:  497,  1904.  (Nev.)  2.  Aubrey, 
Calif.  State  Min.  Bur.,  Bull.  38:  354,  1906.  (Calif.)  3.  Clarke, 
U.  S.  Geol.  Surv.,  Bull.  616:  576,  1916.  (Origin,  many  references.) 
3a.  Dammer  and  Tietze,  Nutzbaren  Mineralien,  I:  85,  1913.  (General.) 
36.  Hess,  U.  S.  Geol.  Surv.,  Bull.  530:  347,  1913.  (San  Rafael  Canon, 
Utah.)  3c.  Hewett,  U.  S.  Geol.  Surv.,  Bull.  540:  477,  1914.  (Park 
Co.,  Wyo.)  3d.  Hewett,  Ibid.,  Bull.  530:  350,  1913.  (Sunlight  Basin, 
Wyo.)  3e.  Hunt,  Econ.  Geol.  X:  543,  1915.  (Origin  and  Sicily.) 
4.  Kemp,  Min.  Indus.,  II:  585,  1894.  (General.)  5.  Kerr,  Assocn. 
Eng.  Soc.  Jour.,  XXVIII:  90,  1902.  (La.)  5a.  Larsen  and  Hunter, 
U.  S.  Geol.  Surv.,  Bull.  530:  363,  1913.  (Mineral  Co.,  Colo.)  6.  Lee, 
U.  S.  Geol.  Surv.,  Bull.  315:  485,  1907.  (Utah.)  6a.  Phalen,  Econ. 
Geol.,  VII:  732,  1912.  (Origin.)  66.  Richards  and  Bridges,  U.  S. 
Geol.  Surv.,  Bull.  470:  499,  1911.  (Ido.)  7.  Richardson,  U.  S.  Geol. 
Surv.,  Bull.  260:  589,  1905.  (Tex.)  8.  Spurr,  U.  S.  Geol.  Surv., 
Prof.  Pap.  55:  157,  1906.  (Sulphur  and  alum,  Silver  Peak,  Nev.) 
8a.  Stutzer,  Die  Nicht-Erze,  Berlin,  1911.  (General.)  9.  Thomas, 
Mining  World,  XXV:  213,  1906.  (Texas.)  10.  Willey,  Eng.  and 
Min.  Jour.,  LXXXIV:  1107,  1907.  (Mining,  La.)  11.  Woodruff, 
U.  S.  Geol.  Surv.,  Bull.  380:  373,  1909.  (Thermopolis,  Wyo.)  12. 
Woodruff,  U.  S.  Geol.  Surv.,  Bull.  340:  451,  1908.  (Cody,  Wyo.) 
13.  Min.  and  Sci.  Press,  Aug.  10.  1907.  (Colo.) 

PYRITE 

Properties  and  Occurrences.  —  Pyrite,  FeS2,  when  chemically 
pure,  has  46.6  per  cent  iron  and  53.4  per  cent  sulphur,  and  occurs  in 
well-defined  cubes  or  modifications  of  the  same,  in  irregular  grains 
or  as  granular  masses,  of  a  brassy  yellow  color. 

It  is  widely  distributed  in  nature,  being  found  in  many  kinds  of 
rocks  and  in  all  formations,  and  in  these  may  occur  as  disseminated 
grains,  in  contact  zones,  as  concretions  in  sedimentary  rocks,  in 
fissure  veins,  and  as  lenticular  bodies  of  variable  size  usually  in 
metamorphic  rocks. 

Pyrite  as  mined  is  never  chemically  pure,  but  contains  admix- 
tures of  other  sulphides,  as  well  as  non-metallic  minerals. 
I    If  chalcopyrite  is  present  in   sufficient  quantity  to  bring  the 
copper  content  of  the  ore  above  3  or  4  per  cent,  the  material  may  be 


MINOR   MINERALS 


401 


sold  for  copper  making  instead  of  acid  manufacture.  Pyrrhotite  is 
abundant  in  some  of  the  Virginia  deposits.  In  some  regions  the 
pyrite  carries  enough  gold  to  render  its  extraction  profitable,  but 
such  deposits  are  not  worked  for  their  sulphur  contents. 

Pyrite  as  offered  to  the  trade  rarely  contains  over  43  per  cent 
sulphur,  and  if  the  content  falls  below  38  per  cent,  the  acid  makers 
object.  Careful  sorting  and  jigging  of  the  pyrite  is  usually  neces- 
sary. Lead,  zinc,  arsenic,  antimony  or  selenium  are  objection- 
able. 

The  pyrite  produced  in  the  United  States  is  obtained  from  (1) 
Massive  deposits,  often  of  lenticular  form  and  disseminations 
occurring  in  gneisses  or  schists  (Va.,  N.  Y.);  (2)  from  the  lead 
and  zinc  mines  of  the  Upper  Mississippi  Valley;  and  (3)  from  the 
coal  mines  of  Indiana  and  Illinois. 

When  pyrite  is  roasted  SO2  is  given  off,  which  is  changed  to  SO3  by  mixing 
with  fumes  given  off  from  a  mixture  of  NaNO3  and  H2SO3  in  properly  con- 
structed lead  chambers.     In  thoroughly  roasted  pyrite  there  remains  a  resi- 
due of  iron  oxide,  which  is  known  as  "  blue  billy  "  or  purple  ore,  and  can  be 
used  in  the  blast  furnace  for  iron  manufacture.     The  roasted  chalcopyrite 
is  sometimes  also  used  for  copper  making. 

Distribution  in  the  United  States.  —  The  most  important  domes- 
tic occurrences  are  found  in  a  belt  of  pre-Cambrian  metamorphic 
rocks  extending  from  New  Hampshire  to  Alabama  (8),  in  which  the 
pyrite  occurs  in  lenticular  deposits.  Virginia  and  New  York  are 
the  most  important  eastern  producers.  California  is  the  only 
western  state  producing  appreciable  quantities. 

Virginia  (7,  8).  —  The  counties  of  Louisa  and  Prince  William 
contain  workable  deposits  of  pyrite,  which  have  been  most  exten- 
sively developed,  and  yield  a  little  more  than  half  of  the  total  domes- 
tic production. 


riG.  128.  — Plan  of  pyrite  lenses  at  Sulphur  Mines,  Louisa  County,  Va.,  showing 
pyrite  (a)  and  crystalline  schists  (6).     (After  Watson,  Min.  Res.,  Va.,  1907.) 


402 


ECONOMIC   GEOLOGY 


FIG.  129.  —  Plan  of  pyrite  lens  (a),  showing  stringers  of  pyrite,  interleaved  with 
schists  (6)  on  hanging  wall.  Arminius  mine,  Louisa  County,  Va.  (After  Watson, 
Min.  Res.,  Va.,  1907.) 

In  these  counties  the  pyrite  occurs  as  bodies  of  lenticular  shape 
(Figs.  128, 129),  in  quartz-mica  schists,  which  may  contain  more  or 
less  hornblende  and  garnet  locally  developed.  The  schists,  which 
are  completely  and  thickly  foliated,  have  a  general  strike  of  N.  10 
to  20°  E.,  and  a  variable  dip. 

The  pyrite  is  massively  granular,  and  the  associated  minerals  in 
the  order  of  their  importance  are  sphalerite,  chalcopyrite,  galena, 
pyrrhotite,  and  magnetite.  Calcite,  quartz,  green  hornblende,  and 
red  garnet  are  present,  but  the  last  two  rather  favor  the  margin  of 
the  ore  bodies. 

The  lenses  of  pyrite  follow  each  other  along  the  strike,  sometimes 
overlapping,  and  may  also  be  connected  by  stringers  of  ore  (Fig. 
129).  The  main  bodies  may  be  several  hundred  feet  long,  indeed 
one  in  Louisa  County  has  a  length  of  700  feet  and  a  thickness  of  60 
to  80  feet.  Another  in  Prince  William  County  is  1000  feet  long. 
Pinches  and  swells  are  common,  and  while  the  pyrite  bodies  are  usu- 
ally sharply  denned,  they  may  at  times  grade  into  the  country  rock. 

An  analysis  of  Louisa  County  pyrite  gave:  S,  49.27;  Fe,  43.62; 
Cu,  1.50;  Zn,  .38;  insol.,  4.23;  CaO  and  MgO,  1.32.  Traces  of 
arsenic  may  be  present.  The  sulphur  averages  43  to  45  per  cent. 

Watson  considers  that  the  inclosing  schists  are  undoubtedly 
metamorphosed  sedimentary  limestones,  as  shown  by  the  presence 
of  bands  and  stringers  of  impure  limestones  arid  the  abundant  de- 
velopment of  lime-bearing  silicates.  The  pyrite  is  believed  to 
have  been  formed  by  replacement. 

The  ore  is  worked  by  underground  methods,  the  schist  picked  out, 
and  the  pyrite  crushed  and  jigged.  The  entire  output  is  used  for  acid 
making.  The  gossan  of  the  pyrite  was  originally  worked  for  iron  ore. 

Sulphuric  acid  is  also  obtained  from  the  pyrrhotite-chalcopyrite  depos- 
its of  Carroll  County,  etc.  These  are  mentioned  under  Copper. 


MINOR  MINERALS 


403 


New  York  (2,  5a).  —  Pyrite  deposits  are  worked  near  Canton  and  Gouver- 
neur,  St.  Lawrence  County.  The  pyrite  is  low  grade,  carrying  20  to  35 
per  cent  sulphur  which  can  be  raised  to  45  to  50  per  cent  by  concentration. 
The  ore  deposits,  which  are  associated  with  crystalline  limestones  and 
schists  of  the  Grenville  series,  appear  to  represent  impregnation  zones  in 
the  schist,  which  by  local  enrichment  may  give  lens-like  accumulations. 

Massachusetts  (3,  5).  —  Pyrite  was  produced  near  Davis,  Franklin  County. 
The  material  forms  a  somewhat  tabular  deposit  of  irregular  width  in  steeply 
dipping,  northeasterly  striking,  crystalline  schists.  The  deposits  have 
been  opened  up  along  the  strike  for  about  900  feet,  and  to  a  depth  of  1400 
feet  on  the  dip.  Horses  of  country  rock  occur  in  the  pyrite.  Five  feet  is 
regarded  as  the  minimum  workable  thickness.  Garnets  and  chalcopyrite 
are  present,  the  latter  forming  either  masses  or  veins  in  the  pyrite.  An 
analysis  of  the  pyrite  concentrates  yielded,  S,  47  per  cent;  Fe,  44  per  cent; 
SiO-2,  3  per  cent;  Cu,  1.5  per  cent;  Zn,  trace;  As,  none. 

Other  States.  —  Some  pyrite  is  produced  from  deposits  in  crystalline  schist 
in  Clay  County,  Alabama  (8),  near  Acworth  and  Villa  Rica,  Georgia,  and  in 
California  (1).  In  Indiana,  Illinois,  and  Ohio  some  is  obtained  as  a  by- 
product in  the  mining  of  coal  (6). 

Not  a  little  pyrite  (marcasite)  is  obtained  from  the  Wisconsin  - 
Illinois  lead-zinc  district.  Some  of  it  is  a  by-product  of  the  sepa- 
rating plants,  but  the  greater  part  is  shipped  as  mined,  and  may 
often  average  45  per  cent  sulphur. 

ANALYSES  OF  PYRITE  AND  PYRRHOTITE 


I 

II 

III 

IV 

V 

VI 

VII 

VIII 

IX 

S.    .   ' 

49.27 

32.10 

44.95 

47.00 

34.060 

48.00 

49.00 

45.00 

44.78 

Fe     . 

43.62 

35.  94141.  14 

44.00 

53.150 

43.00 

43.55 

42.50 

37.49 

Cu    . 

1.50 

.30 

.28 

1.50 

.866 

1.6 

3.20 

3.50 



Zn     . 

.38 

4.68 

3.58 

tr. 



1.5 

.35 

.25 

4.23 

Insol. 

4.23 

U3.42 

M2.54 

^.OO 

*2.99 

15.0 

1.70 



11.08 

CaO. 

^i          r 

1.00 

. 







.14 

.10 

.87 

MgO. 

/    '     t 

.59 

.70 









.20 

As     . 



.04 

.04 





.47 



.07 

Pb     . 

• 

.50 

.40 







.93 

.20 

.14 

SiO2. 


I.  Louisa  County,  Va.  II.  Crude  ore,  Louisa  Co.,  Va.  III.  Concentrates, 
Louisa  Co.,  Va.  IV.  Concentrates,  Davis,  Mass.  V.  Pyrrhotite, 
Virginia.  VI.  New  Hampshire.  VII.  Rio  Tinto,  Spain.  VIII.  Suli- 
telma,  Norway.  IX.  Meggen,  Ger. 

Canada  (9).  —  Pyrite  deposits  are  known  at  a  number  of  points 
in  Canada,  especially  in  Ontario  and  Quebec,  but  comparatively 
few  of  them  are  in  active  operation: 


404 


ECONOMIC   GEOLOGY 


According  to  Fraleck,  the  pyrite  bodies  are  divisible  into  3 
classes,  viz:  (1)  Those  in  gneissoid  rocks;  (2)  those  of  the  iron 
formation,  including  the  Helen  Mine  deposits,  where  the  pyrite 
occurs  in  the  hematite;  and  those  of  the  crystalline  limestones  of 
eastern  Ontario;  (3)  deposits  associated  with  crystalline  schists, 
with  eruptive  greenstones  near  by.  The  ore  bodies  are  frequently 
of  lenticular  form. 

Pyrite  of  slightly  cupriferous  character  is  obtained  from  Eustis 
and  Weedon,  Quebec  (la).  It  is  described  under  Copper. 

Other  Foreign  Deposits.  —  France,  Germany,  Italy,  Norway,  Portugal, 
and  Spain  are  all  large  producers  of  pyrite,  but  only  the  last-named  country 
serves  as  an  important  source  of  supply  for  the  United  States. 

The  Huelva  deposits  of  Spain,  with  Rio  Tinto  as  an  important  producing 
town,  consist  of  lenticular  ore  bodies  in  schist.  The  ore  is  said  to  rarely 
fall  below  47  per  cent  sulphur. 

Some  of  these  are  referred  to  in  more  detail  under  Copper  (Chapter  XVI). 

Uses  of  Pyrite. — Pyrite  is  used  chiefly  and  in  increasing  quan- 
tities for  the  manufacture  of  sulphuric  acid.  About  75  per  cent 
of  the  production  is  from  pyrite,  marcasite  and  pyrrhotite,  while 
the  rest  represents  by-product  acid  made  in  connection  with 
copper  and  zinc  smelting. 

This  acid  is  used  in  the  manufacture  of  superphosphates  and 
explosives,  in  refining  crude  oil,  and  other  ways. 

Production  of  Pyrite.  — 


PRODUCTION  OF  PYRITE  IN  THE  UNITED  STATES,  1910-1911,  IN  LONG  TONS 


1910 

1 

911 

STATE 

Quantity 

Value 

Aver- 
age 
Price 

Ton 

Quantity 

Value 

Aver- 
age 
Price 

Ton 

California     .     .     .     .     . 

27,158 

$129,504 

$4.77 

48,415 

$182,787 

$3  78 

i 

i 

i 

Indiana    

2 

2 

2 

>     6,223 

26,155 

4.20 

Oklahoma     







10,502 

33,747 

3  21 

17441 

47  020 

2  70 

Massachusetts  

New  York    

>  38,978 

187,071 

4.80 

59,215 

282,373 

4.77 

Ohio 

3  766 

12  831 

3  41 

6471 

18  017 

2  78 

148  653 

565  358 

3  80 

150800 

558  494 

3  70 

Wisconsin     

12,555 

49,467 

3  94 

12,893 

50,025 

3  88 

Total    

241,612 

$977,978 

$4.05 

301,458 

$1,164,871 

$3.86 

1  Included  with  Virginia.  2  Included  with  Illinois. 

3  Included  with  Massachusetts  and  New  York. 


MINOR  MINERALS  405 

PRODUCTION  OF  PYRITE  IN  THE  UNITED  STATES,  1912-1914,  IN  LONG  TONS 


1912 

1913 

STATE 

Quantity 

Value 

Aver- 
age 
Price 

Ton 

Quantity 

Value 

Aver- 
age 
Price 

Ton 

61  812 

$201,453 

$3.26 

70,536 

$218,525 

$3.10 

i 

i 

i 

11,110 

55,094 

4.96 

1,462 

5,684 

3.89 

1,242 

3,115 

2.51 

i 

i 

i 

i 

i 

Oklahoma     











27,008 

62,980 

2.33 

11,246 

31,966 

2.84 

Massachusetts  
New  York          .           .     . 

i 

i 

i 

i 

i 

i 

Ohio    

14,487 

43,853 

3.03 

13,622 

34,998 

2.57 

162  478 

621  219 

3.82 

148,259 

587,041 

3.96 

17,898 

70,518 

3.94 

25,328 

94,727 

3.74 

Other  States 

65  783 

328,552 

4.99 

59,995 

260,618 

4.34 

Total              * 

350,928 

$1,334,259 

$3.80 

341,338 

$1,286,084 

3.77 

1914 

STATE 

Quantity 

Value 

Average 
Price 
per  Ton 

71  272 

$235,129 

$3.30 

Georgia    

i 
1,710 

i 
5,281 

i 
3.09 

Missouri  

i 

i 

i 



22,538 

59,079 

2.62 

New  York    

i 

i 

i 

Ohio                     

7,279 

19,718 

2.71 

Pennsylvania    

141  276 

556*091 

3  94 

14,188 

78,460 

5.53 

78,399 

329,588 

4.20 

336,662 

$1,283,346 

$3.81 

1  Included  with  other  states. 


WORLD'S  PRODUCTION  OF  IRON  PYRITE  IN  1913 


COUNTRY 

LONO 
TONS 

COUNTRY 

LONG 
TONS 

Canada 

141  577 

Portugal 

371  588 

United  States  .... 

341  338 

912,316 

Belgium       

264 

Sweden  

33,799 

Bosnia  and  Herzegovina    .     . 

7  580 

Turkey                       .... 

i 

France    .... 

306  267 

11  427 

German  Empire  (Prussia) 

224  808 

Japan     .          

i 

Hungary      .     .     . 

104  950 

Total 

3  177  713 

Italy  
Norway  

287,477 
434  342 

45  per  cent  content)  . 

1,429,971 

1  Statistics  not  available. 


406 


ECONOMIC   GEOLOGY 


Canada. — The  production  of  pyrite  in  1914  amounted  to  224,956 
short  tons,  valued  at  $735,514,  while  the  exports  were  89,999  short 
tons,  valued  at  $377,985. 

Imports. — The  imports  of  pyrite  in  1914  amounted  to  1,026,617 
long  tons,  valued  at  $4,797,236.  They  came  chiefly  from  Spain, 
with  some  from  Portugal,  Canada,  and  Newfoundland. 


PRODUCTION  OF  SULPHURIC  ACID   FROM  COPPER  AND  ZINC   SMELTERS   IN 
1912-1914,  IN  SHORT  TONS 

(Reduced  to  60°  Baume"  acid) 


1912 

1913 

1914 

SOURCE 

SHORT 
TONS 

VALUE 

PRICE 

PER 

TON 

SHORT 
TONS 

VALUE 

PRICE 

PER 

TON 

SHORT 
TONS 

VALUE 

PRICE 

PER 

TON 

Copper 

smelters 
Zinc 
smelters 

321,156 
292,917 

$1,985,704 
2,255,237 

$6.18 
7.70 

336,019 
296,218 

$2,205,627 
2,140,645 

$6.56 
7.23 

348,727 
411,911 

$2,215.690 
2,974,603 

$6.35 
7.22 

Total 
Total    acid 
reduced 
to  50°  B. 

614,073 
764.237 

$4,240,941 

$6.91 

632,237 
790,296 

$4,346,272 

$6.87 

760.638 
950,798 

$5.190.293 

$6.82 

REFERENCES    ON   PYRITE 

1.  Anon.,  Cal.  State  Min.  Bureau,  Bull.  38:  349,  1906;  and  Bull.  23:  144, 
la.  Bancroft,  Dept.  Coin.,  Mines  and  Fisheries,  1915.  (E.  Que.)  Ib. 
Bradley,  Min.  and  Metal  Soc.  Amer.,  VI:  276,  1913.  (Calif.)  Ic. 
Emmons,  U.  S.  Geol.  Surv.,  Bull.  432:  1910.  (Me.  and  N.  H.).  Id.  Mace, 
Min.  and  Eng.  Wld.,  XXXV:  1320,  1911.  (Calif.)  le.  Moore,  Ont. 
Bur.  Mines,  XX,  Pt.  I:  199,  1911.  (Vermilion  Lake.)  2.  Newland, 
N.  Y.  State  Museum,  Bull.  93:  945,  1905;  Bull.  102:  122,  1906;  Bull. 
132:  51,  1909.  (N.  Y.)  3.  Phalen,  U.  S.  Geol.  Surv.,  Min.  Res., 
1908.  (Brief  description,  Mass,  and  Va.)  4.  Phillips,  Amer.  Fert., 
XXVI:  10,  1907.  5.  Rutledge,  Eng.  and  Min.  Jour.,  LXXXII:  674, 
724,  and  722,  1906.  (Mass.)  5a.  Smyth,  N.  Y.  State  Mus.,  Bull. 
158:  143,  1912.  (N.  Y.)  6.  Struthers,  Min.  Indus.,  XI:  577,  1903. 
(General.)  7.  Watson,  Min.  Res.,  Va.,  Lynchburg,  1907:  190.  (Va.) 

8.  Wendt,  Sch.  of  M.  Quart.,  VII:   218,  1885.     (Alleghanies  deposits.) 

9.  Wilson,  Can.  Dept.  Mines,  Mines  Branch,  No.  167,  1912.     (Can.) 


MINOR  MINERALS  407 

TALC  AND  SOAPSTONE 

Properties  and  Occurrence.  —  Talc,  a  hydrous  magnesium  sili- 
cate [H2Mg3(Si03)4],  is  a  widely  distributed  mineral,  but  rarely 
occurs  in  large  quantities. 

It  is  characterized  by  its  extreme  softness,  soapy  feel,  and  freedom 
from  grit.  The  color  is  white,  gray,  or  green;  and  though  generally 
foliated,  it  may  be  fibrous. 

Soapstone  is  a  term  ordinarily  applied  to  a  dark,  bluish  gray  or 
greenish  rock,  composed  essentially  of  talc,  but  containing  other 
minerals  as  impurities,  such  as  mica,  chlorite,  amphibole  (tremo- 
lite),  pyroxene  (enstatite),  and  also  quartz,  magnetite,  pyrrhotite, 
and  pyrite.  It  too  is  soft  enough  to  be  easily  cut  with  a  knife,  and 
has  a  pronounced  soapy  or  greasy  feel. 

Talc  is  an  alteration  product  of  other  magnesia  minerals,  such  as 
tremolite,  actinolite,  pyroxene  or  enstatite,  and  is  often  associated 
with  talcose  or  chlorite  schists,  serpentine,  and  such  basic  igneous 
rocks  as  peridotite  and  pyroxenite.  It  is  also  found  associated  with 
dolomite. 

Soapstone,  which  often  forms  large  masses,  is  found  chiefly  in 
association  with  the  older  crystalline  rocks.  In  some  cases,  it  has 
no  doubt  been  derived  from  an  altered  eruptive  rock,  but  in  others 
probably  from  magnesian  sediments  by  metamorphism. 

Distribution  in  the  United  States.  —  The  production  of  talc 
and  soapstone  is  limited  almost  exclusively  to  the  belt  of  old  crys- 
talline rocks  forming  the  axis  of  the  Appalachian  Mountain  system, 
and  although  quarried  in  eight  or  ten  states,  but  few  are  important 
producers,  and  these  are  mentioned  below. 

Deposits  of  talc  and  soapstone  are  known  in  some  of  the  western 
states,  but  commercial  conditions  have  not  been  favorable  for 
their  development.  Small  quantities  of  talc  have  been  produced 
in  the  past  in  both  California  and  Washington. 

Virginia  (11). — This  state  is  the  most  important  producer  of 
soapstone,  and  while  the  material  is  found  at  a  number  of  localities 
in  the  state,  nearly  the  entire  production  comes  from  a  narrow 
northeast  belt  at  least  thirty  miles  long,  extending  from  Nelson 
into  Albemarle  counties. 

The  soapstone  occurs  in  a  number  of  dike-like  masses  called 
"  veins,"  30  to  165  feet  in  thickness,  and  separated  by  intervals 
of  500  to  800  feet. 

The  deposits  dip  southeast  60°,  conformable  with  the  inclosing 


408  ECONOMIC  GEOLOGY 

crystalline  schists,  which  vary  from  a  mica-quartz  schist  to  a  mica- 
ceous sandstone.  Occasionally  the  wall  rock  is  a  dark  graphite 
schist,  or  an  altered  basic  eruptive. 

The  soapstone  varies  in  color  from  light  bluish  gray  to  dark  greenish 
gray,  the  former  or  higher  grade  containing  the  most  talc,  and  being  the 
easiest  and  most  satisfactory  to  work. 

Under  the  microscope  the  better  grade  is  seen  to  consist  mostly  of  talc, 
with  small  quantities  of  chlorite,  magnetite,  as  well  as  traces  of  amphibole 
and  pyroxene.  The  dark  green  soapstone  owes  its  color  and  greater 
hardness  in  part  to  chlorite  and  other  silicates,  such  as  hornblende  and 
pyroxene.  The  product  is  used  mainly  for  laundry  tubs,  while  smaller 
amounts  are  converted  into  table  tops,  sinks,  and  switch  boards.  Much  of 
it  is  shipped  to  foreign  markets. 

New  York  (10).  —  All  of  the  talc  mined  in  the  state  is  obtained 
from  a  small  area  southeast  of  Gouverneur.  The  most  abundant 
country  rocks  of  this  area  are  pre-Cambrian  gneisses,  in  which 
there  occur  irregular  northeast-southwest  belts  of  crystalline  lime- 
stone, the  greater  portion  of  which  is  impure.  The  schistose  layers 
of  impurities  carry  tremolite  and  enstatite  as  their  chief  constitu- 
ents, and  it  is  the  alteration  of  these  that  has  produced  the  talc,  the 
change  being  indicated  by  the  following  equations  :  — 

ENSTATITE  TALC 

4MgSi03  +  H2O  +  C02  =  H2Mg3Si4012  +  MgC03 

TREMOLITE  TALC 

H20  +  CO2  =  H2Mg3Si4O12  +  CaC03 


This  change  of  the  enstatite  and  tremolite  to  talc  is  supposed  to 
have  been  accomplished  by  the  action  of  water  charged  with  CO*, 
but  whether  it  occurred  at  shallow  or  greater  depths  is  uncertain. 
The  talc  layer,  which  varies  in  thickness  from  a  few  feet  to  over  50 
feet,  averaging  about  20,  shows  either  a  fibrous  or  bladed  structure. 
It  is  used  mainly  as  a  filler  for  writing  papers,  being  even  exported 
to  Europe. 

North  Carolina  (9).  —  The  talc  deposits  of  this  state  form  an  interesting 
contrast  with  those  of  Virginia,  for  here  the  material  occurs  as  a  series  of 
lenticular  masses  and  sheets  in  blue  and  white  Cambrian  marbles,  thus 
indicating  its  probable  derivation  from  a  sedimentary  rock.  In  other  de- 
posits the  talc  is  found  in  a  Cambrian  conglomerate,  in  Archaean  rocks 
associated  with  peridotite,  showing  an  undoubted  derivation  from  igneous 
rocks. 

The  first-mentioned  group  is  associated  with  the  Murphy  Marble,  in 


MINOR   MINERALS 


409 


Swain  County,  and  forms  lenticular  bodies,  with  a  maximum  size  of  50 
feet  thickness  and  200  feet  length.  It  crumbles  down  under  weathering 
action,  and  the  deposits  are  detected  by  float  material.  Most  of  the  North 
Carolina  talc  is  ground  to  powder,  but  some  is  sawed  into  slabs,  or  made  into 
pencils,  crayons,  gas  tips,  etc. 

Vermont  (5).  -  Talc  occurs  at  a  number  of  localities  in  Vermont,  some 
of  which  are  worked.  That  worked  at  East  Granville  is  a  talc  schist,  in- 
closed between  other  schists.  That  at  Chester  and  Athens  occurs  in  gneiss. 

New  Jersey  (8).  —  Talc  has  been  found  at  a  number  of  points  in  the 
vicinity  of  Phillipsburg,  New  Jersey,  and  also  across  the  river  near  Easton, 
Pennsylvania.  The  talc  occurs  with  serpentine  in  dolomite  and  near  pegma- 
tite intrusions.  The  latter  by  contact  metamorphism  developed  tremolite, 
white  pyroxene,  and  phlogopite  in  the  limestone.  Later,  during  break-thrust 
faulting,  accompanying  minor  folding,  squeezing,  and  faulting  in  this  area, 
the  magnesian  silicates  were  altered  by  water  to  talc  and  other  products. 

The  following  analyses  from  several  localities  show  the  kind  and 
quantity  of  impurities  which  good  talc  may  contain:  — 


ANALYSES  OF  TALC 


I 

II 

III 

IV 

V 

VI 

VII 

VIII 

IX 

Si02      . 

62.42 

60.15 

63.07 

60.26 

57.08 

61.85 

60.60 

60.20 

63.36 

A1203    . 
Fe203    . 

1.43 
2.38 

.74 
.09 

1.56 

.31 

J8.40 

/2.61 

.30 

1.25 
2.50 

.46 

FeO      . 



5.05 

.67 

.12 





.60 



.30 

MgO     . 

30.24 

28.71 

28.76 

33.04 

27.16 

34.52 

35.30 

27.98 

27.60 

CaO      . 

tr. 

.04 

.30 

.28 

1.72 

tr. 

.40 

2.60 

3.49 

Na2O    . 



.22 

.79 

.24 





2.80 





K2O      . 



.32 

tr. 





.17 







H2O  ign. 

3.35 

4.11 

4.36 

5.01 

5.15 

.60 



5.70 

3.92 

I.  Foliated  talc,  Burton,  Rabun,  Co.,  Ga.;  II.  Pencil  grade  talc,  Chats- 
worth,  Murray  Co.,  Ga.;  III.  Kinsey  Mine,  North  Carolina;  IV. 
Fibrous  talc,  New  York;  V.  Vermont;  VI.  Luzenach,  France;  VII. 
Valley  of  Pignerolles,  Italy.  Nos.  I  to  VII  quoted  in  Ref.  7.  VIII. 
Sheep  Creek,  Calif.;  IX.  Seven  miles  southeast  Riggs  Station,  Calif., 
Nos.  VIII,  IX,  Ref.  3. 


Georgia  (7).  —  Talc  formed  from  limestone  is  found  in  Fannin  and  Gilmer 
counties,  but  is  not  extensively  worked.  Deposits  of  greater  importance, 
are  those  worked  in  Murray  County.  These  occur  in  the  Ocoee  (Cambrian) 
series,  the  talc-bearing  formations  dipping  45°  southeast.  The  talc  occurs 
as  lenses  associated  with  a  harder  impure  form  known  as  blue  John,  between 
walls  of  quartz  schist.  It  is  supposed  to  be  derived  from  igneous  rocks. 


410  ECONOMIC   GEOLOGY 

California  (3).  —  Talc  deposits  which  occur  in  San  Bernardino  and  Inyo 
counties,   California,  have  recently   undergone    considerable    development. 


FIG.  130.  — Section  of  talc  deposit  near  Tecopa,  Calif., t,  talc  with  some  limestone 
tremolite,  schist  and  serpentine;  b,  banded,  somewhat  cherty  limestone,  125 
feet;  s,  lighter  colored,  less  ferruginous,  and  apparently  dolomitic  limestone; 
d,  diorite.  (After  Diller,  U.  S.  Geol.  Surv.,  Min.  Res.,  1913.) 

The  talc  is  usually  quite  white,  and  lies  on  the  contact  between  diorite  and 
banded  limestone,  but  is  very  irregular  in  its  thickness.  Tremolite  and 
serpentine  are  found  in  association  with  the  talc.  It  has  been  used  chiefly 
in  the  manufacture  of  tiles. 

Canada  (l,  4).  —  Talc  is  mined  only  in  Madoc  township,  Hastings 
County,  Ontario.  The  material,  which  is  massive  and  white, 
occurs  in  a  brown  quartzose  limestone  of  the  Grenville  series.  It 
varies  from  25  to  40  feet  in  width,  and  has  been  mined  for  a 
horizontal  distance  of  about  500  feet.  There  seems  to  be  no 
doubt  that  the  talc  has  been  formed  by  the  alteration  of  magnesian 
limestone,  although  the  exact  process  is  not  clear,  except  that  the 
neighboring  granite  intrusion  may  have  yielded  silica-bearing 
solutions.  Soapstone  deposits  have  been  worked  intermittently 
in  southern  Quebec  (4). 

Other  Foreign  Deposits  (12).  — The  largest  European  talc  deposits  are 
those  on  the  north  side  of  the  Pyrenees  in  southern  France.  The  material 
lies  between  mica  schists  and  Ordovician  slates,  and  contains  beds  of  lime- 
stone, as  well  as  scattered  granite  blocks.  Another  important  occurrence 
is  that  found  in  Styria,  where,  in  a  saddle-shaped  fold  the  talc  lies  between 
an  underlying  graphite  slate,  and  an  overlying  limestone  of  Silurian  age. 
The  talc  is  supposed  to  have  been  derived  by  the  alteration  of  the  graphitic 
slate  and  grades  into  it.  A  similar  and  important  occurrence  of  pure  talc 
is  worked  near  Pinerolo  in  northern  Italy.  Numerous  other  foreign  deposits 
are  known,  but  they  are  much  less  important  than  the  above-mentioned 
ones. 

Uses. — Talc  is  marketed  as  rough  talc,  sawed  slabs,  or  ground 
talc.  Its  peculiar  physical  character,  extreme  fineness,  softness, 
and  freedom  from  grit  adapt  it  to  a  number  of  uses,  of  which  the 
following  are  most  important:  fireproof  paints,  foundry  facing  , 
boiler  and  steam-pipe  coverings,  soap  adulterants,  toilet  powders, 
dynamite,  in  wall  plasters,  for  dressing  skins  and  leather,  as  a 


MINOR  MINERALS 


411 


base  for  lubricants,  as  a  filling  for  paper,  and  for  sizing  cotton 
cloth.  It  has  been  used  to  a  slight  extent  for  adulterating  food. 
It  can,  on  account  of  its  softness,  be  easily  sawed  or  carved,  and 
is  extensively  used  for  washtubs,  sanitary  appliances,  laboratory 
tanks  and  tables,  electrical  switchboards,  hearthstones,  mantels, 
footwarmers,  etc.  Most  of  the  New  York  fibrous  talc  is  used  as  a 
paper  filler,  being  better  suited  for  it  than  the  North  Carolina 
product.  The  compact  Varieties  of  pure  talc  are  employed  for 
pencils,  and  for  coal-  and  acetylene-gas  tips. 

The  average  price  of  rough  talc  in  1914  for  the  whole  United  States  was 
$5.83  a  ton,  but  some  sold  as  low  as  $2.00  per  ton,  and  talc  worked  up  into 
pencils  or  crayons  brought  as  high  as  $100.  The  average  price  for  manu- 
factured talc  in  1914  was  $27.98  per  ton. 

The  prices  of  soapstone  vary  with  the  form  in  which  it  is  sold,  and  also 
with  the  size  and  quality  of  the  stone.  In  the  rough  as  quarried,  its  value 
ranges  from  about  $1.50  to  $2.00  per  ton.  Sawed  slabs  of  good  size  and 
quality  may  exceed  $15.00  per  ton  in  value,  and  when  manufactured  into 
laundry  tubs,  the  average  value  is  about  $30.00  per  ton. 

Pyrophyllite  differs  from  talc  chemically,  being  a  hydrous  alumi- 
num silicate,  instead  of  a  magnesium  silicate,  but  when  sufficiently 
free  from  grit,  it  is  put  to  the  same  use  as  talc.  It  is  sometimes  in- 
correctly called  agalmatolite,  because  of  its  resemblance  to  the 
true  mineral  of  that  name.  Deposits,  more  extensive  than  those 
of  talc,  are  found  near  Glendon,  North  Carolina  (9).  It  varies 
from  green  and  yellowish  white  to  white,  but  in  all  cases  becomes 
nearly  white  when  dried. 

Production  of  Talc  and  Soapstone. — The  production  for  the 
last  four  years  has  been  as  follows : — 

PRODUCTION  OF  TALC  AND  SOAPSTONE,  1911-1914,  BY  STATES,  IN 
SHORT  TONS 


1911 

1912 

1913 

1914 

QUAN- 
TITY 

VALUE 

QUAN- 
TITY 

VALUE 

QUAN- 
TITY 

VALUE 

QUAN- 
TITY 

VALUE 

Massachusetts 
New  Jersey  and 
Pennsylvania 
New  York  .      . 
North  Carolina 
Vermont 
Virginia       .     . 
California   .     . 
Other  states  *  . 

Total       .     . 

7.642 

12,131 
62,030 
3,548 
29,488 
26,759 
i 

1,953 

$  36.883 

54,319 
613,286 
57,101 
200,015 
660.926 
i 

23,488 

i 

10,400 
66,867 
3,542 
42,413 
25.313 
1,169 
9,566 

i 

$  50,519 
656,270 
63,304 
275,679 
576,473 
15,653 
69,065 

i 

11,308 
81,705 
4,676 
45,547 
26,487 
952 
5.158 

i 

$  80.7801 
788,500 
48,817 
327,375 
615,558 
6,000 
41,067 

i. 

7,732 
86,075 
1,198 
50,698 
21,687 
547 
4,?59 

i 

$   54.549 
821,286 
28,413 
363,465 
527.938 
8,786 
60.650 

143,551 

$1,646,018 

159,270 

$1.706,963 

175,833  isl.  908,097 

172,296 

$1.865,087 

' l  Included  in  other  States. 

2  Includes  1911:   California,  Georgia,  Maryland  and  Rhode  Island;    1912,  1913 
and  1914:   Georgia,  Maryland,  Massachusetts  and  Rhode  Island. 


412 


ECONOMIC   GEOLOGY 


The  total  imports  of  talc  in  1914  amounted  to  15,734  tons, 
valued  at  $177,321,  an  increase  of  14.4  per  cent  in  quantity  and 
of  nearly  28.8  per  cent  in  value  as  compared  with  1913. 

,>*• 

PRODUCTION  AND  IMPORTS  OF  CANADIAN  TALC 


YEAR 

PRODUCTION 

IMPORTS 

SHORT  TONS 

VALUE 

/ALUE 

1912  . 

8,270 
12,250 
10,808 

$23,132 
45,980 
40,418 

$  4,414 
10,706 

1913   
1914  

REFERENCES    ON   TALC    AND    SOAPSTONE 

1.  Anon.,  Ont.  Bur.  Mines,  XXII,  Pt.  2:  113,  1913.  (Madoc,  Ont.)  2. 
Anon.,  Maryland  Mineral  Industries,  1896-1907,  Md.  Geol.  Surv., 
special  publication,  VIII,  Pt.  2,  p.  160.  (Md.)  3.  Diller,  U.  S.  Geol. 
Surv.,  Min.  Res.,  1913:  157,  1914.  (Calif.)  4.  Dresser,  Can.  Min. 
Inst.,  XII:  177,  1910.  (Que.)  5.  Jacobs,  Ver.  Geol.  Surv.,  Rep. 
1913-14:  382,  1914.  (Vt.)  6.  Keith,  U.  S.  Geol.  Surv.,  Bull.  213: 
443,  1903.  (N.  Ca.)  7.  Hopkins,  Ga.  Geol.  Surv.,  Bull.  29,  1914. 
(Ga.)  8.  Peck,  N.  J.  Geol.  Surv.,  1904  Rept.:  163,  1905.  (N.  J. 
and  Pa.)  Also  Pa.  Top.  and  Geol.  Surv.,  Rep.  5,  1911.  9.  Pratt, 
N.  Ca.  Geol.  Surv.,  Econ.  Papers,  No.  3:  99,  1900.  (N.  Ca.)  10. 
Smyth,  Sch.  of  M.  Quart.,  XVII:  333,  1896.  (N.  Y.  and  bibliography.) 
11.  Watson,  Min.  Res.,  Va.,  Lynchburg:  293,  1907.  (Va.)  12.  Dam- 
mer  and  Tietze,  Nutzbaren  Mineralien,  II:  362,  1914.  (Foreign.) 


TRIPOLI 

Properties  and  Occurrence.  —  The  term  Tripoli  is  somewhat 
loosely  used  to  include  many  siliceous  substances  used  for  abrasive 
purposes,  but  in  this  place  it  is  restricted  to  certain  siliceous  rocks 
found  in  Missouri  (2,  4)  Illinois  (l,  3),  and  Tennessee. 

The  Missouri  tripoli  is  a  light,  porous,  siliceous  rock  which  has 
been  extensively  quarried  near  Seneca,  Missouri,  but  it  is  known 
at  other  localities  in  the  state,  and  even  in  Oklahoma. 

The  deposits  occur  in  the  Boone  (Lower  Carboniferous)  forma- 
tion (4),  consisting  of  alternating  limestones  and  cherts  having  an 
average  thickness  of  350  feet,  and  with  only  an  oolitic  limestone  as 
an  easily  recognized  bed.  The  tripoli  beds,  which  occur  mostly 
above  the  last,  are  4  to  12  feet  thick,  and  overlain  by  chert,  gravel, 
and  red  clay.  Chert  may  also  occur  in  the  tripoli  itself,  and  even 
form  a  large  proportion  of  it. 


MINOR   MINERALS 


413 


The  tripoli  is  an  even-textured,  finely  porous  rock,  whose  grains 
are  mostly  under  .01  mm.  in  diameter,  and  are  probably  chal- 
cedony. The  following  analyses  represent  the  composition  of  the 
stone  from  Seneca,  Missouri:  — 

ANALYSES  OF  TRIPOLI  FROM  SENECA,  Mo. 


1 

2 

3 

SiO     .          ...    '.     

98.28 

98.10 

98.10 

AloOs        

.17 

.24 

.24 

Fe-2Os             

.53 

.27 

.27 

CaO 

tr. 

.184 

33 

K,O     

.17 

Na«0  

.27 

.23 

.23 

leri 

.50 

1.16 

1.17 

Org  

.008 

99.92 

100.192 

100.34 

1.  R.  N.  Brackett,  Ark.  Geol.  Surv.,  V  :  267,  1892.  2.  W.  H.  Seaman, 
Sci.  Am.  Supp.,  July  28,  1894  :  15487.  3.  Mo.  Geol.  Surv.,  VII :  731,  1894. 

A  commonly  accepted  theory  is  that  the  tripoli  results  from  the 
decomposition  of  chert,  but  while  chert  is  in  the  tripoli  beds,  it  is 
not  possible  to  find  a  transition  from  tripoli  laterally  to  unaltered 
rock.  It  is  also  difficult  to  see  how  the  common  chert  of  this  region 
could  form  the  massive,  non-fossiliferous  tripoli. 

Siebenthal  (4)  believes  the  tripoli  to  have  been  derived  by  the 
leaching  of  lime  carbonate  from  beds  like  certain  gray,  dull, 
massive  limestones  now  found  in  this  region. 

In  southern  Illinois,  in  Union  and  Alexander  counties,  there  are 
beds  of  fine-grained  silica,  which  maybe  similar  to  theMissouri  trip- 
oli. Its  origin  and  extent  are,  however,  imperfectly  known.  An 
analysis  yielded  SiO2,  98.00;  MgO,  .20;  A1203,  1.21;  Moist.,  .15; 
Und.,  .44.  The  silica  consists  of  minute  particles  from  .50  to  .2mm. 
diameter,  of  crystalline  structure,  transparent  character,  and  irregu- 
lar shape,  loosely  cemented  by  a  small  amount  of  clay.  It 
may  be  used  for  wood  polishing  and  other  purposes. 

Another  deposit  of  tripoli  is  that  found  near  Butler,  Tenn.  (5). 
It  represents  leached  beds  of  Cambrian  limestone,  and  forms  a 
soft  chalk-like  or  pulverulent  mass,  whose  grains  range  from 
.01  to  .06  mm.  in  diameter. 

The  composition  is:  Si02,  67.85;  A12O3,  16.80;  FeO,  5.06; 
CaO,  .32;  MgO,  .60;  K2O,  5.40;  Na2O,  1.23;  Ignition,  3.47. 


414  ECONOMIC   GEOLOGY 

Uses.  —  The  rough  blocks  are  sawed  up  into  filter  stones,  while 
the  spalls  and  small  pieces  are  ground  up  for  tripoli  flour,  and  there 
has  been  a  great  increase  in  the  production  since  1885.  The 
tripoli  is  worth  $6  to  $7  per  ton  f.o.b.  Tripoli  stone  is  used  to 
some  extent  for  blotter  blocks  and  scouring  bricks.  Tripoli  flour 
is  used  as  an  abrasive  for  general  polishing,  burnishing,  and  buffing, 
and  also  as  an  ingredient  of  scouring  soaps. 

REFERENCES  ON  TRIPOLI 

1.  Bain,  111.  Geol.  Surv.,  Bull.  4:  185,  1907.  (Illinois.)  2.  Hovey,  Sci. 
Amer.  Suppl.,  July  28,  1894,  p.  15487.  (Missouri.)  3.  Parr,  Ernest 
and  Williams,  Jour.  Indus,  and  Eng.  Chem.,  I:  692,  1909.  (Illinois.) 
4.  Siebenthal  and  Mesler,  U.  S.  Geol.  Surv.,  Bull.  340:  429,  1908. 
(Missouri.)  5.  Glenn,  Res.  Tenn.,  IV:  No.  1.  (Tenn.) 

WAVELLITE 

Wavellite  has  been  used  to  a  small  extent  in  the  United  States  as 
a  substitute  for  rock  phosphate,  in  making  phosphorus. 

This  mineral  does  not  usually  occur  in  minable  quantities,  but  a 
somewhat  unique  deposit  has  been  found  on  South  Mountain,  near 
Mount  Holly  Springs,  Pa.  There  the  wavellite  occurs  in  a  white 
residual  clay  derived  from  talcose  schists,  and  associated  with  man- 
ganese and  iron  ores.  The  iron  and  manganese  have  been  concen- 
trated during  the  weathering  of  the  rocks,  and  deposited  in  the 
residual  materials,  near  the  contact  of  the  limestones  of  the  valley 
and  the  mountain  sandstones.  The  phosphate  occurs  as  nodules, 
scattered  through  a  white  clay,  lying  between  a  manganese-bearing 
red  clay  and  the  mountain.  The  width  of  the  deposit  is  40  to  50 
feet.  The  mining  of  this  material  was  reported  by  the  United 
States  Geological  Survey  for  1906,  but  since  then  no  production  has 
been  recorded. 

Phosphorus  is  used  mainly  for  making  matches  as  well  as  for  fuse 
compositions,  rat  and  insect  poison,  phosphoric  acid,  and  for  other 
compounds  used  in  medicine  and  the  arts.  It  is  also  used  in  the 
preparation  of  precious  metals,  electrotyping,  and  in  phosphor 
bronze. 

REFERENCES    ON  WAVELLITE 

1.  Stose,  U.  S.  Geol.  Surv.,  Bull.  315  :  325,  1907.  2.  Hopkins,  Ann. 
Rept.  Pa.  State  College,  1889-1900,  appendix  III :  13. 


PLATE  XXXVII 

D 


FIG.  1.  —  Section  of  an  artesian  basin.  A,  porous  stratum;  B,  C,  impervious  beds 
below  and  above  A,  acting  as  confining  strata;  F,  height  of  water  level  in  porous 
bed  A,  or,  in  other  words,  height  in  reservoir  or  fountain  head;  D,  E,  flowing 
wells  springing  from  the  porous  water-filled  bed  A. 


FIG.  2.  —  Section  illustrating  artesian  conditions  in  jointed  crystalline  rocks  without 
surface  covering.  A,  C,  flowing  wells  fed  by  joints;  B,  intermediate  well  between 
A  and  C  of  greater  depth,  but  with  no  water;  D,  deep  well  not  encountering 
joints;  E,  pump  well  adjacent  to  D,  obtaining  water  at  shallow  depths;  S,  dry 
hole  adjacent  to  a  spring,  showing  why  wells  near  springs  may  fail  to  obtain 
water. 


FIG.  3.  —  Section  illustrating  conditions  of  flow  from  solution  passages  in  limestone. 
A,  brecciated  zone  (due  to  caving  roof)  serving  as  confining  agent  to  waters 
reached  by  well  1 ;  B,  silt  deposit  filling  passage  and  acting  as  confining  agent  to 
waters  reached  by  well  2;  C,  surface  debris  clogging  channel  and  confining 
waters  reached  by  well  3;  D,  pinching  out  of  solution  crevice  resulting  in 
confinement  of  waters  reached  by  well  4. 


FIG.  4.  —  Section  illustrating  conditions  of  flow  from  joints,  cracks,  and  solution 
passages  in  stratified  rocks  covered  by  impervious  clays  and  fed  from  morainal 
drift.  (All  after  Fuller.) 

(415) 


CHAPTER  XIII 


UNDERGROUND  WATERS 

THE  investigation  of  underground  waters  has  assumed  such  in> 
portance  in  the  last  few  years,  that  it  is  hardly  possible  to  do  it 
justice  in  the  limited  space  which  can  be  devoted  to  it  here.  How- 
ever, some  of  the  more  salient  points  can  perhaps  be  touched  upon, 
and  those  who  desire  more  detailed  information  are  referred  to 
the  selected  bibliography  at  the  end  .of  the  topic. 

While  much  of  the  water  used  for  supplying  towns  and  cities, 
for  irrigation  purposes,  etc.,  is  obtained  from  below  the  surface,  all 
of  it  originates  in  rainfall.  The  rain  water  falling  on  the  surface  is 
disposed  of  in  part  by  evaporation  and  surface  run-off,  but  a  vari- 
able and  sometimes  large  percentage  seeps  into  the  ground. 

Ground  Water  (5,  6)  —  A  small  part  of  the  water  soaking  into 
the  ground  is 
retained  by  cap- 
illarity in  the 
surface  soil,  to  be 
returned  again  to 
the  atmosphere, 
either  by  direct 
evaporation  or 
through  plants; 
but  most  of  it 


Rift 


FIG.  131.  —  Ideal  section  across  a  river  valley,  showing  the 
position  of  ground  water  and  the  undulations  of  the  water 
table  with  reference  to  the  surface  of  the  ground  and  bed 
rock.  (After  Slichter,  U.  S.  Geol  Surv.,  Water  Supply 
Bull.  67.) 


finds  its  way  into  deeper  layers  of  the  soil,  which  it  completely 
saturates. 

The  water  in  this  saturated  zone,  which  is  termed  the  ground 
water  (Fig.  131),  forms  a  great  reservoir  of  supply  for  lakes,  springs, 
and  wells;  and  its  upper  surface,  known  as  the  water  table,  agrees 
somewhat  closely  with  that  of  the  land  surface,  but  is  farther  from 
it  under  hills  (Fig.  131),  and  nearer  to  it  under  the  valleys.  Under 
some  depressions  it  may  even  reach  the  surface  and  form  springs 
or  swampy  conditions  (see  Fig.  131).  The  depth  of  the  water 
table  is  quite  variable,  being  but  a  few  feet  below  the  surface  in 

moist  climates,  while  in  arid  regions  it  may  be  100  feet  or  more. 

416 


UNDERGROUND  WATERS 


417 


In  any  area,  however,  the  water  table  may  show  periodical  fluctua^ 
tions,  due  in  part  and  mainly  to  variation  in  the  supply.  Near 
the  coast  line,  the  rise  and  fall  of  the  tide  may  also  affect  it  (Fig.  132) . 
In  all  ground  water  there  is  a  slow  but  constant  movement  from 
higher  to  lower  levels,  just  as  in  the  case  of  surface  waters,  so  that 
the  ground  water  flows  toward  the  valleys.  There  it  may  dis- 
charge into  the  streams,  but  in  some  instances  it  follows  the  valley 
bottom  below  the  river  bed,  separated  from  the  river  water  by  a 
more  or  less  impervious  layer  (6).  The  composition  of  the  ground 
water  also  shows  a  somewhat  close  relation  to  the  rocks  or  soils  in 
which  it  accumulates. 

Artesian  Water.  —  Under  this  heading  are  included  those  waters 
confined  in  rocks  of  consolidated  or  unconsolidated  character,  under 

sufficient  pressure  to  cause  the 
water  to  rise  toward  the  surface, 
along  an  avenue  of  escape,  but 
not  necessarily  high  enough  to 
produce  an  outflow. 

The  artesian  water   found  In 
rocks  may  collect  there  in  cavi- 
ties of  diverse   size,  origin,   and 
FIG.  132.— Section  showing  effect  of  tide   shape,  such  as  pores  between  the 
on  level  of  water  table.    (After  Ellis,   grains,     joint     cracks,     bedding 

U.  S.  Geol.  Surv.,  W.  S.  Bull.  232.)  J,    ,.  ...  ... 

planes,  solution  cavities,  cavities 

due  to  brecciation,  gas  cavities  of  lavas,  etc.  (PL  XXXVII).  The 
surface  water  finds  its  way  down  into  these  open  spaces  in  the  rocks, 
and  if  there  is  some  confining  agent,  such  as  denser  rock,  or  other 
more  or  less  impermeable  barrier,  present,  it  may  be  held  there. 
Under  these  conditions  it  may  be  under  more  or  less  pressure  and  if 
some  avenue  of  escape,  such  as  a  drill  hole,  is  opened  up,  the  water 
rises  towards  the  surface. 

The  requisite  conditions  of  an  artesian  flow  might  therefore  be 
stated  as  follows  (2) :  (1)  adequate  source  of  water  supply;  (2)  a 
retaining  agent  offering  more  resistance  to  the  passage  of  water  than 
the  well  or  other  opening;  (3)  an  adequate  source  of  pressure. 

The  retaining  agent  may  be  a  stratum,  vein,  or  dike  wall,  joint, 
fault,  a  water  layer,  etc.,  while  the  pressure  is  due  primarily  to 
variations  in  level  in  the  different  parts  of  the  artesian  system, 
although  there  may  be  numerous  modifying  factors.  It  will  be 
understood,  from  what  little  has  been  stated  above,  that  a  supply  of 
artesian  water  might  be  found  under  a  variety  of  conditions.  Only 


418  ECONOMIC   GEOLOGY 

two  of  these  will  be  considered  here,  although  several  others  are 
Shown  in  Pis.  XXXVII  and  XXXVIII. 

Stratified  Beds.  —  The  structure  sometimes  found  in  stratified 
rocks  closely  approaches  the  most  favorable  conditions  for  an  ar- 
tesian circulation.  That  is,  we  have  inclined  layers  of  pervious 
rock,  inclosed  between  beds  of  impermeable,  or  but  slightly  per- 
meable, character.  Water  flowing  down  these  permeable  beds, 
either  through  the  pores,  or  in  the  pores  and  joints  together,  may 
accumulate  in  sufficient  quantity  to  yield  a  large  and  sometimes 
steady  supply.  While  sandstones  usually  show  the  highest  porosity 
of  any  of  the  sedimentary  rocks,  limestones  may  also  yield  a  good 
flow,  although  in  these  the  water  must  accumulate  largely  in  the 
joint  planes.  Such  a  structural  type,  composed  of  water-bearing 
beds  between  denser  ones,  may  be  termed  an  artesian  slope  (PI. 
XXXVII, Fig.  l),and  it  is  of  great  importance.  The  wells  tapping 
such  a  supply  are  sometimes  many  miles  from  the  area  of  intake, 
and  may  be  sunk  to  depths  of  as  much  as  2000  feet  in  order  to  reach 
the  water-bearing  bed.  A  more  or  less  tight  bed  over  the  porous 
one  is  essential,  but  the  underlying  bed  need  not  be  impervious. 

A  not  uncommon  type  of  artesian  reservoir  is  that  found  in 
glacial  drift  where  water-bearing  lenses  of  sand  or  gravel  are  over- 
lain or  more  or  less  surrounded  by  clay.  In  this  case  the  water  seep- 
ing downward  from  the  surface  collects  in  the  gravel  pocket. 

There  are  many  areas  in  the  United  States  in  which  the  condi- 
tions are  favorable  to  an  artesian  water  supply  in  stratified  rocks, 
as  the  various  state  and  government  reports  will  show.  A  few  of 
the  more  important  ones  may  be  briefly  referred  to. 

Along  the  Atlantic  and  Gulf  coastal  plain  an  abundant  supply 
of  artesian  water  is  obtained  from  the  Cretaceous  and  Tertiary 
beds  at  depths  varying  from  50  feet  along  the  inland  border,  to 
1000  feet  and  over  along  the  coast  (7,  10,  22,  41,  48)  (Fig.  133). 

A  second  area  is  that  of  the  upper  Mississippi  Valley  (50),  in 
which  an  abundant  supply  of  potable  water  is  obtained  from  the 
St.  Croix  and  St.  Peters  sandstone,  whose  outcrop  in  Minnesota 
and  Wisconsin  covers  some  14,000  square  miles. 

In  the  Great  Plains  (8)  region  water  is  obtained  from  the  Dakota 
sandstone,  whose  collecting  area  is  around  the  border  of  the  Black 
Hills  (Fig.  134)  and  eastern  edge  of  the  Rocky  Mountains.  This 
source  is  available  in  South  Dakota  and  eastern  Nebraska  and 
Kansas  and  Colorado.  The  chief  use  of  the  water  in  this  region 
is  for  irrigation. 


PLATE  XXXVIII 


FIG.  1.  — Section  illustrating  conditions  of  flow  from  foliation  and  schistosity  planes. 
A,  Foliation  plane  feeding  flowing  well  1.    (After  Fuller.) 


FIG.  2.  —  Section  illustrating  conditions  of  flow  from  vesicular  trap.     A,  Vesicular 
zone  feeding  well  1.     (After  Fuller.) 


Fie.  3. — Section  showing  accumulation  of  water  in  stratified  rocks  with  low  intake. 

(After  Ellis.) 

(419) 


420 


ECONOMIC  GEOLOGY 


For  the  arid  regions  of  the  west  this  source  of  supply  has  been  of 
inestimable  value,  and  has  been  the  means  of  reclaiming  many  an 
area  of  hitherto  useless  land. 


FIG.  133.  —  Geologic  section  of  Atlantic  Coastal  Plain,  showing  water-bearing  hori- 
zons.    (After  Darton,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXIV.) 

Crystalline  Rocks.  —  Recent  investigations  have  shown  that  a 
considerable  amount  of  water  may  seep  downward  along  the  ver- 
tical joint  planes  of  crystalline  rocks  (PI.  XXXVII,  Fig.  2),  such  as 
granite,  crystalline  limestone,  gneiss,  and  schist,  and  become  stored 
in  the  horizontal  joint  fissures,  but  owing  to  the  density  of  these 
rocks,  very  little  water  can  accumulate  in  the  pores.  If  now  a  well 


TA  SANDCT 
UITE 


FIG.  134.  —  Section  from  Black  Hills  across  South  Dakota,  showing  artesian  well 

conditions.     (After  Darton.) 

is  drilled  so  as  to  strike  these  water-bearing  joints,  a  more  or  less 
steady  supply  may  be  obtained.  In  most  cases  the  volume  is  not 
more  than  10  gallons  per  minute,  but  occasionally  as  much  as  90 
gallons  has  been  obtained  by  pumping. 

While  the  finding  of  a  supply  of  water  in  crystalline  rocks  is  more 


UNDERGROUND  WATERS  421 

or  less  a  matter  of  chance,  still  the  proportion  of  successful  wells  is 
large,  although  the  possibility  of  success  decreases  greatly  below 
200  feet,  and  is  less  even  below  50  feet  than  above  it. 

A  number  of  wells  have  been  bored  in  the  crystalline  rocks  of 
New  England  and  even  other  eastern  states  (3,  21,  31). 

REFERENCES  ON  UNDERGROUND  WATERS 

ORIGIN  AND  ACCUMULATION.  1.  Chamberlin,  U.  S.  Geol.  Surv.,  5th  Ann. 
Rept.  :  125,  1885.  (Artesian  water  supply.)  2.  Fuller,  U.  S.  Geol. 
Surv.,  Bull.  319,  1908.  (Controlling  factors  of  Artesian  flow.)  3. 
Clapp,  Eng.  Rec.,  LX  :  525,  1909.  (Water  in  crystalline  rocks.)  4. 
Johnson,  U.  S.  Geol.  Surv.,  W.  S.  pap.  122,  1905.  (Relation  of  law  to 
underground  water.)  5.  King,  U.  S.  Geol.  Surv.,  19th  Ann.  Rept.,  II  : 
59,  1899.  (Underground  water  circulation.)  6.  Schlichter,  U.  S. 
Geol  Surv.,  W.  S.  pap.  67,  1902.  (General  on  underground  waters.) 

AREAL.  General:  7.  Darton,  U.  S.  Geol.  Surv.,  Bull.  138,  1896.  (At- 
lantic Coastal  Plain.)  8.  Darton,  U.  S.  Geol.  Surv.,  Prof.  Pap.  32, 
1905.  (Central  Great  Plains.)  9.  Darton,  U.  S.  Geol.  Surv.,  W.  S.  pap. 
149,  1903.  (Deep  well  borings  of  U.  S.)  See  also  Fuller  and  others, 
No.  264,  1905.  10.  Fuller  and  others,  U.  S.  Geol.  Surv.,  W.  S.  pap, 
114, 1905.  (E.  U.  S.)  11.  Fuller,  Ibid.,  No.  100, 1905.  (Hydrography 
U.  S.)  12.  Fuller  and  others,  U.  S.  Geol.  Surv.,  W.  S.  paps.  120,  1905, 
and  163,  1906.  (Bibliography.)  —  Alabama  :  13.  Smith,  Ala.  Geol. 
Surv.,  Bull.,  1907.  —  Arkansas  :  14.  Veatch,  La.  Geol.  Surv.,  Bull.  I. 
1905.  (S.  Ark.)  —  California:  15.  Lee,  U.  S.  Geol.  Surv.,  W.  S.  pap. 
181,  1906.  (Owens  VaUey,  Calif.)  16.  Mendenhall,  Ibid.,  No.  225. 
1909.  (Indio  region.)  17.  Mendenhall,  Ibid.,  No.  222,  1908.  (San 
Joaquin  Valley.)  18.  Mendenhall,  Ibid.,  No.  219,  1908.  (Calif.) 
18a.  Waring,  Ibid.,  No.  338,  1915.  (California  Springs.)  —  Colorado: 
19.  Eldridge,  U.  S.  Geol.  Surv.,  Mon.  27.  (Denver  basin.)  20.  Gil- 
bert, Ibid.,  17th  Ann.  Rept.,  II:  557,  1896.  (Ark.  valley.)  20a. 
Darton,  U.  S.  Geol.  Surv.,  Prof.  Pap.  52,  1906.  (Ark.  Valley.)  —  Con- 
necticut: 21.  Gregory,  U.  S.  Geol.  Surv.,  W.  S.  Pap.  232,  1909.- 
Florida:  21a.  Sellards,  Fla.  Geol.  Surv.,  Bull.  1,  1908.  (Cent.  Fla.) 
and  Matson  and  Sanford,  W.  S.  Paper,  319,  1913.  —  Georgia:  22. 
McCallie,  Ga.  Geol.  Surv.,  Bull.  7,  1899,  and  Stephenson,  et  al,  W.  S. 
Pap.,  341,  1915.  (Coastal  Plain.)  —  Illinois:  23.  Udden,  111.  Geol. 
Surv.,  Bull  8:  313,  1907.  (Peoria  district.)  24.  Savage,  Ibid.,  Bull. 
4:  235,  1907.  (Springfield  quadrangle.)  25.  Leverett,  U.  S.  Geol. 
Surv.,  17th  Ann.  Rept.,  II:  701,  1896. —  Indiana:  26.  Leverett,  U. 
S.  Geol.  Surv.,  W.  S.  Pap.  Nos.  21  and  26,  also  Capps  and  Dole,  W.  S. 
Pap.  254,  1910.  (N.  cent.  Ind.)  —  Iowa:  27.  Norton,  la.  Geol.  Surv., 
XXI,  1912.  — Kansas:  27a.  Haworth,  W.  S.  Pap.  6,  1897. —  Ken- 
tucky: 28.  Matson,  U.  S.  Geol.  Surv.,  W.  S.  Pap.  233,  1909.  (Blue 
grass  region).  Also  Glenn,  W.  S.  Pap.  164,  1906. —Louisiana:  29. 
Harris,  and  Veatch  La.  Geol.  Surv.,  Bull.  I,  1905.  30.  Harris,  U.  S. 
Geol.  Surv.,  W.  S.  Pap.  101,  1904.  (S.  La.)  —  Maine:  31.  Clapp  and 
Bayley,  U.  S.  Geol.  Surv.,  W.  S.  Pap.  223,  1909.  —  Michigan:  32. 


422  ECONOMIC  GEOLOGY 

Lane,  U.  S.  Geol.  Surv.,  W.  S.  Paps.  30"  and  31.  33.  Leverett,  Ibid., 
183,  1907. —  Mississippi:  34.  Crider  and  Johnson,  U.  S.  Geol.  Surv., 
W.  S.  Pap.  159,  1907. —  Missouri:  35.  Shepard,  U.  S.  Geol.  Surv., 
W.  S.  Pap.  195,  1907.  —  Montana:  36.  Fisher,  U.  S.  Geol.  Surv., 
W.  S.  Pap.,  221,  1909.  (Great  Falls  Region.)  —  Nebraska:  37.  Condra, 
U.  S.  Geol.  Surv.,  W.  S.  Pap.  215,  1908.  (N.  E.  Neb.).  See  also  Ref. 
8. —  New  Hampshire:  38.  Smith,  U.  S.  Geol.  Surv.,  W.  S.  Pap.  145, 
J905.  (Portsmouth,  region)  —  New  Jersey:  39.  Woolman,  N.  J. 
Geol.  Surv.,  Ann.  Rept.,  1902:  59,  1903.  See  also  Jlef.  7.  —  New 
Mexico:  40.  Lee,  U.  S.  Geol.  Surv.,  W.  S.  Pap.  188,  1907.  (Rio 
Grande  valley.)  —  New  York:  41.  Veatch  and  others,  U.  S.  Geol. 
Surv.,  Prof.  Pap.  44,  1905.  (Long  Island.)  —  Ohio:  41cr.  Fuller  and 
Clapp,  W.  S.  Pap.  259,  1912.  (S.  W.  Ohio.)  —  Oklahoma:  42.  Gould, 
U.  S.  Geol.  Surv.,  W.  S.  Pap.  148,  1905.  —  Oregon:  43.  Waring,  U. 
S.  Geol.  Surv.,  W.  S.  Pap.  220,  1908.  (S.  Cent.  Ore.)— Texas:  44. 
Gould,  U.  S.  Geol.  Surv.,  W.  S.  Pap.  191,  1907.  (Panhandle  region.) 
45.  Taylor,  Ibid.,  No.  190,  1907,  and  Deussen,  Ibid.,  335,  1914.  (S. 
E.  Tex.)  (Coastal  plain.) —Utah:  46.  Lee,  U.  S.  Geol.  Surv.,  W.  S. 
Pap.  217,  1908.  (Beaver  Valley.).  47.  Richardson,  Ibid.,  No.  157, 
1906.  (Utah  Lake  and  Jordan  River.)  —  Virginia:  48.  Watson,  Min. 
Res.  Va.:  259,  1907,  and  Sanford,  Va.  Geol.  Surv.,  Bull.  IV,  1913. 
-Washington:  49.  Ruddy,  Wash.  Geol.  Surv.,  I:  296,  1901.  — Wis- 
consin: 50.  Kirchoffer,  Bull.  Univ.  Wis.,  No.  100,  1905.  (General.) 
51.  Weidman,  Wis.  Geol.  Surv.,  Bull.  16:  666,  1907.  (Crystallines 
area,  N.  Cent.  Wis.)  —  Wyoming:  52.  Knight,  Wyo.  Univ.  Exper. 
Sta.,  Bull.  45,  1900. 

MINERAL  WATERS 

This  term  is  commonly  applied  to  those  spring  waters  containing 
a  variable  amount  of  dissolved  solid  matter  of  such  character  as 
to  make  them  of  medicinal  value.  Their  origin,  although  often 
regarded  as  curious,  is  simple,  the  dissolved  substances  having  been 
derived  from  the  rocks  through  which  the  spring  waters  have  circu- 
lated. Many  mineral  waters  contain  carbonic  and  even  other  acids, 
and  alkalies,  which  further  increase  their  powers  of  solution.  There 
is  apparently  some  connection  between  hot  mineral  springs  and 
geological  structure,  as  they  are  more  abundant  in  regions  of  fault- 
ing or  recent  volcanic  activity.  Waters  flowing  from  shallow 
sources  usually  show  the  lowest  mineralization,  and  those  derived 
from  sedimentary  rocks  often  show  a  greater  quantity  of  dissolved 
material  than  those  occurring  in  igneous  rocks. 

Springs  whose  temperature  is  above  70°  F.  are  termed  thermal, 
those  between  70°  F.  and  98°  F.  being  classed  as  tepid,  and  those 


UNDERGROUND  WATERS 


423 


hotter  than  this  as  hot  springs.  The  following  will  serve  as  ex- 
amples to  show  the  temperature  of  different  thermal  springs :  Sweet 
Springs,  West  Virginia,  74°  F.;  Warm  Springs,  French  Broad 
River,  Tennessee,  95°;  Washita,  Arkansas,  140°  to  156°;  San 
Bernardino  Hot  Springs,  California,  108°  to  172°;  Las  Vegas,  New 
Mexico,  110°  to  140°. 

The  volume  of  discharge  shown  by  mineral  springs  is  quite  vari- 
able. The  famous  Orange  Spring  of  Florida  discharges  5,055,000 
gallons  per  hour,  while  others  are  as  follows:  Champion  Springs, 
Saratoga,  New  York,  2500  gallons;  Roanoke  Red  Sulphur  Springs, 
Virginia,  1278  gallons;  Warm  Sulphur  Springs,  Bath,  Virginia, 
360,000  gallons;  Glen  Springs,  Waukesha,  Wisconsin,  45,000 
gallons. 

While  a  classification  of  mineral  waters  may  be  geographic,  geo- 
logic, therapeutic,  or  chemical,  that  prepared  by  A.  C.  Peale  is 
perhaps  as  satisfactory  as  any.  He  subdivides  mineral  waters  into 
the  following  classes :  — 


Alkaline 

Alkaline-saline 

"  Sulphated 
k  Muriated 

Sodic 
Lithic 

Potassic 

Saline              .    {Sulphated 
i  Munated 

Calcic 
Magnesic 

Chalybeate 

Aluminous 

'  Sulphated 

Acid  .... 

Muriated 

Siliceous        f  Sulphated 

I  Muriated 

The  springs  falling  in  the  above  groups  may  be  either  thermal  or 
nonthermal,  and  may  be  either  free  from  gas  or  contain  C02,  H2S, 
N,  or  CH4. 

Other  classifications  will  be  found  in  references. 

Most  mineral  water  classifications  are  unsatisfactory,  partly  for  the 
reason  that,  although  they  give  the  important  salt  present  in  each  class,' 
they  do  not  give  the  amount,  'a  matter  of  some  importance.  Thus  it  has 
been  pointed  out  for  example  that  two  mineral  waters  might  contain,  re- 
spectively, 250  and  2000  parts  per  million  of  mineral  matter  of  the  same 
relative  composition,  and  would  therefore  fall  in  the  same  class.  Both 
might  be  carbonated,  sodic,  calcic,  muriated,  alkaline-saline.  Now  the 
former  woulcl  be  satisfactory,  but  the  latter  would  not  only  be  too  hard  for 
household  uses,  but  would  contain  so  much  salt  as  to  give  it  a  decided  taste. 

Again,  it  is  important  in  some  cases  to  know  the  probable  combinations 
present.  To  a  physician  it  is  immaterial  to  know  whether  sulphates  present 


424 


ECONOMIC  GEOLOGY 


are  those  of  sodium  or  magnesium,  since  they  have  similar  medicinal  effects. 
The  engineer  must  know  which,  as  the  former  is  harmless,  while  the  latter 
forms  boiler  scale. 

Distribution  of  Mineral  Waters  in  the  United  States.  —  There 
are,  according  to  Peale,  between  eight  and  ten  thousand  mineral 
springs  in  the  United  States,  and  of  this  number  695  reported  pro- 
duction, 1908.  The  majority  of  the  commercially  valuable  mineral 
springs  are  located  in  the  eastern  United  States  and  Mississippi 
Valley.  West  of  the  101st  meridian  they  are  confined  chiefly  to 
the  Pacific  coast.  No  thermal  springs  are  known  in  the  New 
England  states.  Among  the  American  springs,  those  at  Saratoga, 
New  York,  have  an  international  reputation,  and  compare  well 
with  many  of  the  foreign  ones.  Others  of  importance  are  the  Hot 
Springs  of  Virginia  and  the  Hot  Springs  of  Arkansas. 

The  following  table  contains  the  analyses  of  several  types  of 
mineral  waters  from  the  United  States :  — 

ANALYSES  OF  AMERICAN  MINERAL  WATERS 


03 

a 

. 

o 

p 

O 
Z 

•1 

B 

o 

.    H 

1*1 

I 

1     •§ 

1   g 

l|  2 

CHEMICAL,  CONSTITUENTS 

M         '      fc 

5  £  o 

-      - 

CO    ^  « 

A    § 

g 

X 

tf| 

g^Jl 

!  y 

juj 

11° 

ggo 

s  3 

li 

I§il 

•I  § 

ill 

K    ^    W 

*  «  £* 

*  §  § 

»  i 

°°  <  3  5 

j  ^  ^ 

00    &    J 

§00  3 

X  CO    ^ 

jlS 

0    B 

O    S   w   P 
W  OQ   3  OQ 

*^  § 

1^3 

O      c» 

W        OD 

£      0 

WH 

P4      <! 

^    <: 

PQ     <! 

gr.  per 
gal. 

gr.  per 
gal. 

gr.  per 

gr.  per 
gal. 

gr.  per 
gal. 

gr.  per 
gal. 

gr.  per 
gal. 

Sodium  carbonate    . 



5.00 

Sodium  bicarbonate 

10.77 

8.75 



— 

.49 



1.26 

Sodium  sulphate 

— 

— 





— 

16.27 

.54 

Calcium  carbonate  . 
Magnesium  carbonate 
Calcium  bicarbonate 

143.40 

41.32 

5.22 

j  3.17 
12.66 

12.93 

11.41 

17.02 

Magnesium  bicarbonate 

121.76 

29.34 



.69 



12.39 

Lithium  bicarbonate 

4.76 









Trace 

Iron  bicarbonate 

.34 

3.00 

— 

2.17 

— 

— 

.04 

Magnesium  sulphate 
Potassium  sulphate 

.89 

2.15 

1.38 

18.96 

— 

— 

Sodium  chloride  . 

400.44 

166.81 



.33 

27.34 

.46 

Potassium  chloride 

8.05 





1.16 

Potassium  bromide 

— 

1.57 







— 

— 

Sodium  bromide  . 

8.56 













Sodium  iodide     . 

.14 

4.67 











Silica      .     . 

84 

.53 

1.72 

.38 

45 

2.51 

.74 

Calcium  sulphate     . 

14^53 

2^54 

96164 

Production  of   Mineral   Waters.  —  The  production  of  mineral 
waters  in  the  United  States  for  the  last  five  years  was  as  follows :  — 


UNDERGROUND  WATERS 


425 


PRODUCTION  OF  MINERAL  WATER  IN  THE  UNITED  STATES,  1910-1914 


YEAR 

COMMERCIAL 
SPRINGS 

GALLONS  SOLD 

VALUE 

1910              .                .     . 

709 

62  030,125 

$6  357  590 

1911    
1912 

732 
746 

63,788,552 
62  281,201 

6,837,888 
6  615  671 

1913   
1914   

838 
829 

57,867,399 
54,358,466 

5,631,391 
4,892,328 

RANK  OF  STATES  BASED  ON  SPRINGS  REPORTING,  ON  QUANTITY  SOLD,  AND 
ON  VALUE  OF  OUTPUT,  1914 


RANK 

NUMBER  OF 
SPRINGS 
REPORTING 

QUANTITY 
SOLD 

VALUE  OF 
MEDICINAL 
WATERS 

VALUE  OF 
TABLE 
WATERS 

TOTAL 
VALUE 

1 

New  York 

New  York 

California 

New  York 

New  York 

2 

Massachusetts 

Minnesota 

Indiana 

Wisconsin 

Wisconsin 

3 

Virginia 

Wisconsin 

Virginia 

California 

California 

4 

California 

Ohio 

Texas 

Maine 

Maine 

5 
6 

Pennsylvania 
Connecticut 

Massachusett  t 
Virginia 

Maine 
Wisconsin 

Pennsylvania 
Minnesota 

Virginia 
Pennsylvania 

7 

Missouri 

Pennsylvania 

Arkansas 

Virginia 

Minneosta 

8  / 

Ohio 

Connecticut 

New  York 

Massachusetts 

Massachusetts 

Wisconsin 

9 

Texas 

California 

Missouri 

New  Jersey 

New  Jersey 

10 

Maine 

Illinois 

Kansas 

Connecticut 

Ohio 

REFERENCES  ON  MINERAL  WATERS 

Bailey,  Kas.  Geol.  Surv.,  VII  :  1902.  (Kas.)  2.  Bartow,  Udden,  Parr, 
and  Palmer,  111.  Geol.  Surv.,  Bull.  10,  1909.  (General  and  111.)  3. 
Branner,  Ark.  Geol.  Surv.,  Rept.,  I,  1891.  (Ark.)  4.  Crook,  Mineral 
Waters  of  United  States  and  their  Therapeutic  Value.  (N.  Y.,  1899.) 
5.  Hay  wood,  U.  S.  Dept.  Agricult.,  Dept.  Chem.,  Bull.  91.  (Classi- 
fication.) 6.  Lane,  U.  S.  Geol.  Surv.,  Water  Supply  Bull.  XXXI, 
1899.  7.  Peale,  U.  S.  Geol.  Surv.,  14th  Ann.  Rept.,  II  :  51.  (U.  S.) 
8.  Schweitzer,  Mo.  Geol.  Surv.,  Ill,  1892.  (Mo.,  also  general.) 


PART   II 

ORE  DEPOSITS 


CHAPTER  XIV 
ORE    DEPOSITS 

Definition.  —  The  term  ore  deposits  is  applied  to  concentrations 
of  economically  valuable  metalliferous  minerals  found  in  the  earth's 
crust,  while  under  the  term  ore  are  included  those  portions  of  the 
ore  deposit  of  which  the  metallic  minerals  form  a  sufficiently  large 
proportion  and  are  in  the  proper  combination  to  make  their  extrac- 
tion possible  and  profitable.  The  term  ore  mineral  can  be  applied 
to  those  minerals  carrying  the  desired  metallic  elements  which 
occur  within  the  deposit.  These  ore  minerals  may  in  some  cases 
make  up  the  entire  mass  of  the  ore. 

A  metalliferous  mineral  or  rock  might  therefore  not  be  an  ore  at 
the  present  day,  but  become  so  at  a  later  date,  because  improved 
methods  of  treatment  or  other  conditions  rendered  the  extraction 
of  its  metallic  contents  profitable. 

A  few  metallic  minerals  serving  as  ore  minerals,  such  as  gold, 
copper,  platinum,  and  mercury,  sometimes  occur  in  a  native  condi- 
tion ;  but  in  most  cases  the  metal  is  combined  with  other  elements, 
forming  sulphides,  oxides,  carbonates,  sulphates,  silicates,  chlor- 
ides, phosphates,  or  rarer  compounds,  the  first  five  of  these 
being  the  most  numerous.  A  deposit  may  contain  the  ore  minerals 
of  one  or  several  metals,  and  there  may  also  be  several  compounds 
of  the  same  metal  present. 

Gangue  Minerals.  —  Associated  with  the  economically  valuable 
metallic  minerals  there  are  usually  certain  common  ones,  of  metallic 
or  non-metallic  character,  which  carry  no  values  worth  extracting. 
These  are  termed  the  gangue  minerals.  They  often  form  masses 
in  the  ore  deposit  which  can  be  avoided  or  thrown  out  in  mining, 
but  at  other  times  they  are  so  intermixed  with  the  valuable  metal- 
liferous minerals  that  the  ore  is  crushed  and  the  two  separated 
by  special  methods. 

Quartz  is  the  most  abundant  gangue  mineral,  but  calcite,  barite, 
fluorite,  and  siderite  are  also  common,  while  dolomite,  hornblende, 
pyroxene,  feldspar,  rhodochrosite,  etc.,  are  found  in  some  ore  bodies. 
x  429 


430  ECONOMIC  GEOLOGY 

Origin  of  Ore  Bodies.  —  The  fact  that  ores  form  masses  of  greater 
or  less  concentration  is  explainable  in  two  ways :  either  they  have 
been  formed  at  the  same  time  as  the  inclosing  rock  (contempora- 
neous or  syngenetic) ;  or  else  they  have  been  formed  by  a  process  of 
concentration  at  a  later  date  (subsequent  or  epigenetic).  The  first 
theory  is  found  to  be  applicable  to  some  ores  in  igneous  rocks, 
and  to  some  sedimentary  ones,  while  the  second  applies  to  most 
ere  deposits,  regardless  of  the  character  of  the  inclosing  rock. 

It  must  not  be  inferred  from  this,  however,  that  the  origin  of  all 
known  ore  bodies  has  been  definitely  settled,  for  a  strong  difference 
of  opinion  sometimes  exists  among  geologists  regarding  the  same 
deposit,  and  some  have  been  placed  first  in  one  class  and  then  in 
another;  but  with  all  this  shifting  the  number  of  occurrences 
falling  in  the  syngenetic  class  has  increased  considerably  and  now 
includes  some  large  and  important  ore  deposits. 

Syngenetic  Deposits.  —  These  may  be  divided  into  two  groups, 
viz.  those  of  magmatic  origin,  and  those  of  sedimentary  origin. 

Magmatic  Segregations  (2,  4,  13,  21,  52-60).  —  Under  this  head- 
ing is  included  a  small  class  of  deposits,  whose  intimate  associa- 
tion with  igneous  rocks  proves  beyond  doubt  that  they  have  been 
derived  from  the  igneous  magma  by  a  process  of  segregation  dur- 
ing their  crystallization  from  it. 

These  separations  generally  take  place  during  the  early  stages 
of  cooling,  and  form  the  first  of  a  series  of  minerals,  usually  crystal- 
izing  out  in  a  somewhat  definite  order. 

The  order  of  crystallization  stated  by  Rosenbusch,  and  which  applies 
especially  to  granitic  and  dioritic  rocks,  there  being  some  exceptions  for  more 
basic  ones,  is  as  follows: 

1.  Iron    ores  and  accessory  constituents  (magnetite,  hematite,  ilmenite, 
apatite,  zircon,  spinel,  titanite,  etc.). 

2.  Ferromagnesian  silicates  (olivine,  pyroxene,  amphibole,  mica,  etc.). 

3.  Feldspathic  constituents  (feldspars  and  feldspathoids,  including  leucite, 
nephelite,  sodalite,  etc.). 

4.  Free  silica  (quartz). 

We  see  then  that  the  crystallizations  show  an  order  of  decreasing  basicity. 
Moreover,  if  the  magma  contains  watei,  this  is  retained  in  part  in  the  still 
fluid  or  molten  part,  so  that  finally  we  may  have  a  mixture  of  silica,  possibly 
some  alkalies,  water  and  other  mineralizers  (fluorine,  boron,  etc.). 

Separations  of  the  heavy  metals  appear  to  be  characteristic 
of  igneous  magmas  deficient  in  acid-forming  constituents,  but  this 
is  not  surprising,  for  a  consideration  of  the  composition  of  igneous 


ORE   DEPOSITS  431 

rocks  shows  us  that  since  the  basicity  of  an  eruptive  rock  depends 
partly  on  the  percentage  of  the  oxides  of  heavy  metals,  the  basic 
ones  are  more  apt  to  yield  magmatic  separations  than  the  acid  ones. 
In  some  cases,  however,  metallic  concentrations  occur  in  acid 
rocks. 

In  these  segregations  it  is  seen  that  the  metallic  minerals  which 
have  gathered  together  to  form  the  ore  deposits  are  simply  common 
accessory,  and  not  important,  constituents  of  the  igneous  rocks. 
That  is,  the  ore  body  and  the  country  rock  contain  the  same  min- 
erals, but  the  relative  abundance  of  the  silicates  and  metallic 


FIG.  135. —  Chromite  in  olivine  (in  part  altered   to  serpentine),  from  Kraubath, 

Austria.     X 15. 

minerals  is  reversed.  As  an  example:  the  average  percentage 
of  chromium  in  the  rocks  of  the  earth's  crust  is  about  .01  per  cent. 
In  a  peridotite  magma  it  forms  about  .2  per  cent,  but  in  segrega- 
tions within  the  magma  we  find  40  to  60  per  cent  C^Os. 

Where  the  metallic  minerals  crystallize  out  and  segregate, 
the  ore  body  forms  a  portion  of  the  igneous  mass,  and  usually 
grades  off  into  it,  but  in  some  cases  the  ore  minerals  have  not  only 
become  differentiated  from  the  parent  magma,  but  this  separated 
portion  has  been  forced  up  from  below,  independent  of  the  rest 
of  the  igneous  mass,  thus  forming  a  true  dike. 

The  end  products  in  the  cooling  of  a  magma,  which  crystallize 
out  as  pegmatite  dikes  or  quartz  veins,  may  sometimes  carry 
metals,  such  as  tin  (North  Carolina)  or  gold  (Silver  Peak,  Nev.) 


432  ECONOMIC   GEOLOGY 

and  these  are  likewise  regarded  by  some  as  magmatic  syngenetic 
deposits. 

Ores  formed  by  magmatic  segregation  show  a  crystalline  text- 
ure (Fig.  164),  usually  of  coarse,  but  sometimes  fine,  grain. 
Porphyritic  texture  is  sometimes  developed  in  these  deposits, 
the  phenocrysts  being  ore  minerals.  Graphic  inter-growths  may 
occur,  and  while  some  believe  it  indicates  that  the  magma  con- 
tained a  eutectic  mixture  of  two  minerals  which  crystallized  at 
the  same  time,  this  view  is  not  held  by  all  geologists. 

Form  of  Magmatic  Ore  Bodies.  —  Ore  deposits  formed  by 
magmatic  segregation  not  only  show  a  varying  degree  of  con- 
centration, but  vary  greatly  in  their  size  and  form.  Some 
exhibit  vast  dimensions,  as  the  Scandinavian  iron  ore  deposits 
of  Kirunavara  and  Luossavara  (Fig.  162);  indeed,  [these  are 
much  larger  than  any  of  this  type  known  in  North  America, 
the  nearest  approach  to  them  being  the  nickel  deposits  of  Sud- 
bury-Ontario. 

Magmatically  segregated  ore  bodies  may  occur :  (1)  as  irregu- 
larly distributed  deposits,  which  show  a  transition  into  the  sur- 
rounding igneous  rock;  (2)  as  deposits  on  the  border  of  the  igne- 
ous rock,  but  lying  mainly  within  the  former  and  sending  tongues 
out  into  either;  or  (3)  as  dikes  in  the  igneous  rock.  In  the  latter 
case  they  might  be  regarded  as  very  basic  segregations,  which  have 
been  forced  up  from  below,  subsequent  to  the  intrusion  of  the  basic 
rock  itself.  (See  Iron  ore,  Wyoming.) 

As  stated  above,  the  number  of  ore  deposits  formed  by  magmatic 
segregation  is  small  in  number,  but  the  following  types  can  probably 
be  referred  to  this  class  : 

1.  Titaniferous  iron  ores  in  basic  and  intermediate  eruptives 
(Adirondacks,   New  York,  Iron  Mountain,  Wyoming,  etc.),  and 
perhaps  some  iron  ores  in  acid  eruptives  (Mineville,  New  York). 

2.  Chromite  in  peridotites  and  the  secondary  serpentines. 

3.  Some  sulphide  ores  (Sudbury,  Ontario,  and  Lancaster,  Penn- 

sylvania) (?). 

4.  Nickel-iron  ores  in  eruptive  rocks  (no  value). 

5.  Platinum  in  basic  eruptives  (no  value). 

6.  Tin  ores  in  some  pegmatites  (South  Carolina). 

7.  Some  gold  ores  in  quartz  veins  (Silver  Peak,  Nevada).1 
Syngenetic  Deposits  cf  Sedimentary  Origin.  —  If  ores  in  sedi- 
mentary rocks  are  of  contemporaneous  origin  they  must  have  been 

1  These  would  be  referred  to  the  deeper  vein  zone  by  some. 


ORE   DEPOSITS  433 

formed  at  the  same  time  as  the  rock  in  which  they  occur,  the 
process  being  either  a  chemical  or  mechanical  one,  similar  to  that 
by  which  the  different  kinds  of  stratified  rocks  have  been  formed. 
Two  classes  might  be  recognized,  viz.  (!)  interstratified  deposits, 
and  (2)  surficial  deposits  or  placers. 

Interstratified  sedimentary  deposits.  —  These  may  have  originated 
by  processes  analogous  to  those  which  have  formed  the  inclosing 
rocks.  Some  may  have  accumulated  by  precipitation  from  sea 
water  or  fresh  water,  a  process  which  is  going  on  even  at  the  present 
day,  as  shown  by  the  deposition  of  limonite  in  ponds,  or  the  forma- 
tion of  nodules  of  limonite,  pyrite,  or  manganese  on  the  ocean  bot- 
tom. 

Others  may  be  of  mechanical  origin,  the  grains  of  metallic 
minerals  having  been  set  free  by  disintegration  of  rocks  on  the  land, 
and  the  particles  later  becoming  segregated,  as  in  the  case  of  magne- 
tite sands,  formed  along  the  beaches  by  wave  action.  Both  types 
may  be  subsequently  covered  up  by  other  sediments,  or  in  rarer 
cases  by  igneous  flows. 

Sedimentary  deposits  of  the  two  types  just  mentioned  are  of 
tabular  form,  and  thin  out  horizontally  in  all  directions,  but  many 
of  them  are  of  great  extent  and  even  of  curiously  uniform  char- 
acter, as  for  example  the  Clinton  ores  of  the  eastern  United  States 
(p.  538),  the  bedded  limonites  of  France  and  Germany  (p.  556) 
or  the  hematite  of  Newfoundland  (p.  546).  They  are  sometimes 
sharply  separated  from  the  inclosing  rocks,  or  at  others  grade  into 
them.  Further  characteristics  to  be  noted  are  the  absence  of 
fragments  of  the  overlying  country  rock  in  the  ore  and  of  veinlets 
branching  off  from  the  bed.  If  folding  of  the  rocks  has  occurred, 
the  beds  follow  the  folds.  Sedimentary  deposits  are  occasionally 
enriched  by  water  circulating  through  the  beds  and  causing  a 
concentration  of  the  contents,  either  by  removal  of  soluble  ele- 
ments, addition  of  metallic  compounds  or  rearrangement  of  those 
present.  Syngenetic  bedded  deposits  often  show  a  fine-grained 
texture.  In  cases  they  are  oolitic  or  even  fossiliferous,  the  metal- 
lic minerals  in  part  replacing  the  fossils.  Some  may  show  finely 
crystalline  quartz  and  also  finely  crystalline  secondary  minerals. 

Placer  deposits.  —  This  term  is  applied  to  deposits  of  gravel, 
sand,  or  even  clay,  containing  heavy  metallic  minerals  like  gold, 
cassiterite,  platinum,  etc.,  concentrated  usually  by  mechanical 
agents  such  as  streams,  waves  or  wind. 

When  the  products  of  rock  decay  are  washed  down  the  slopes 


434  ECONOMIC  GEOLOGY 

and  into  the  streams,  the  lighter  material  is  carried  off  to  sea,  while 
the  heavier  particles  such  as  pebbles  and  metallic  mineral  grains 
remain  behind  in  the  stream  channels.  The  metallic  fragments 
by  reason  of  their  higher  specific  gravity  settle  to  the  bottom  of 
the  channel,  and  all  become  more  or  less  rounded  by  the  rubbing 
action  they  are  subjected  to  while  being  moved  along  by  the  stream 
current. 

Placer  deposits  may  also  be  formed  along  beaches  by  wave 
action,  while  a  rare  type  are  those  which  originate  in  dry  climates 
by  the  disintegration  of  rock,  little  of  the  material  being  removed, 
except  sandy  particles  which  are  blown  away  by  the  wind.  A 
somewhat  special  type,  called  eluvial  placers,  originates  by  the 
weathering  of  gold-bearing  rocks,  the  residual  products  remaining 
at  the  point  of  origin,  or  migrating  a  short  distance  down  grade. 
The  gold  in  these  is  rough  and  angular.  Eluvial  placers  are  known 
in  the  southern  Appalachians. 

From  what  has  been  said  above,  one  must  not  get  the  idea 
that  placer  deposits  did  not  form  in  the  past,  for  they  did,  and  are 
known  to  exist  in  sedimentary  formations  as  far  back  as  the 
Cambrian.  (See  Gold,  South  Dakota.) 

Epigenetic  Ore  Deposits.  —  These,  as  previously  stated,  are  of 
later  age  than  the  inclosing  rock.  In  other  words,  they  have  been 
concentrated  in  the  rocks  by  natural  processes. 

In  order  to  demonstrate  this  it  is  necessary  to  show:  (1)  the 
source  of  the  metals  found  in  the  rocks;  (2)  the  existence  of  a  car- 
rier which  could  transport  the  metals,  in  solution  probably ;  and  (3) 
the  existence  of  conditions  favorable  to  the  precipitation  of  the  ore. 

Occurrence  of  Metals  in  the  Rocks.  —  It  is  well  known  that 
metallic  minerals  in  small  quantities  are  widely  distributed,  in  both 
igneous  and  sedimentary  rocks.  Sandberger  (18),  for  example, 
has  shown  by  analyses  the  presence  of  nickel,  copper,  lead,  tin, 
and  cobalt  in  such  minerals  as  hornblende,  olivine,  and  mica;  and 
Curtis  has  found  traces  of  silver,  gold,  and  lead  in  the  quartz-por- 
phyries at  Eureka,  Nevada,1  and  silver,  arsenic,  lead,  copper, 
and  gold  in  the  granite  at  Steamboat  Springs,  Nevada.2  Grout 3 
found  .029  per  cent  copper  in  Keweenawan  traps  of  Minnesota, 
while  Lewis4  recorded  .025  per  cent  CuO  in  the  New  Jersey  dia- 

!U.  S.  Geol.  Surv.,  Mon.  VII:   80. 
2  Ibid.,  Mon.  XIII:  350. 
8  Econ.  Geol.,  V:  471,  1910. 
4  Ibid.,  II:   242,  1907. 


ORE   DEPOSITS  435 

base.  Winslow  has  pointed  out  the  presence  of  small  quantities 
of  lead  and  zinc  in  the  limestones  of  Missouri  and  Wisconsin  (see 
lead  and  zinc  references) ,  and  Wagoner  has  made  similar  tests  on 
California  sediments  (172).  Since,  however,  the  sediments  were 
originally  derived  from  the  igneous  rocks,  it  follows  that  the 
latter  must  be  the  original  source  of  the  minerals.1  It  is  interesting 
to  note  that  even  in  the  igneous  rocks  the  metals  are  not  impar- 
tially distributed,  but  that  certain  metals  seem  to  favor  certain 
rocks.2  Thus  iron,  manganese,  nickel,  cobalt,  chromium,  and 
platinum,  seem  to  favor  basic  rocks;  while  tin,  tungsten,  and  some 
rarer  metals  favor  the  acid  ones.  Titanium  has  been  found  in 
both  acid  and  basic. 

While  the  occurrence  of  metallic  minerals  in  the  rocks  of  the 
earth's  crust  is  widely  recognized,  few,  perhaps,  realize  the  small 
percentage  existing  outside  of  those  concentrated  portions,  the 
ore  deposits;  and  the  following  table,  showing  the  average  com- 
position of  rocks  of  the  earth's  crust,3  will  serve  to  emphasize 
this  point: 

Oxygen      .     .     ...     .     .     .     47.29  Manganese 078 

Silicon       28.02  Sulphur .103 

Aluminum 7.96  Barium 092 

Iron      . 4.56  Chromium .033 

Calcium 3.47  Nickel 020 

Magnesium 2.29  Lithium 004 

Potassium 2.47  Chlorine 063 

Sodium 2.50  Fluorine 10 

Titanium       ......         .46  Zirconium 017 

Hydrogen .16  Vanadium 017 

Carbon 13  Stiontium  . 033 

Phosphorus 13 

An  examination  of  the  above  figures  shows  that,  of  some  twenty 
metals  that  are  of  importance  to  us  for  daily  use,  only  five,  viz. 
aluminum,  iron,  manganese,  chromium,  and  nickel,  are  included 
in  the  above  list,  and  that  the  others  must  be  present  in  amounts 
of  less  than  .01  per  cent. 

Professor  Vogt  4  has  endeavored  to  estimate  the  approximate 
average  amount  present  of  other  important  (economically)  metals, 

1  For  a  most  interesting  discussion  of  this  see  Siebenthal,  U.  S.  Geol.  Surv., 
Bull.  606:   67,  1915. 

2  De  Launay,  Ann.  d.  Min.,  Aug.,  1897. 

3  Clarke,  U.  S.  Geol.  Surv.,  Bull.  616:   27,  1916. 

4  Zeitschr.  prak.  Geol.,  July  and  Sept.,  1898. 


436 


ECONOMIC   GEOLOGY 


not  included  in  the  table  on  page  435.  According  to  him,  the 
percentage  amount  of  tin,  zinc,  and  lead  is  expressed  by  a  digit 
in  the  third  or  fourth  decimal  place,  copper  in  fourth  or  fifth, 
silver  in  sixth  or  seventh,  gold  and  platinum  in  seventh  or  eighth. 
Mercury  would  show  a  slightly  larger  percentage  than  silver,  and 
arsenic,  antimony,  molybdenum,  and  tungsten,  between  copper 
and  silver.  Bismuth,  selenium,  and  tellurium  would  be  placed 
between  silver  and  gold  in  the  list. 

Lindgren  (13)  differs  somewhat  from  Vogt,  and  would  place  the 
percentage  of  copper  at  .01  to  .005,  zinc  at  .004  per  cent  and  lead 
at  .002  per  cent.  He  suggests  that  silver  may  constitute  .00001 
per  cent  of  the  earth's  crust,  and  gold  .0000005  per  cent. 

As  actual  examples  of  the  amounts  present,  we  may  quote  the 
following  determinations  made  on  eruptive  rocks  from  several 
localities : — 


METAL 

PER  CENT 

LOCALITY 

Copper            

,009 

Missouri 

Copper                      .     . 

.029 

Minnesota 

Lead      

.0011 

Colorado 

Lead.                          .     • 

.004 

Missouri 

Zinc       ....... 

.009 

Missouri 

Silver          

.00007 

Leadville,  Colo. 

Silver                         .     .     . 

.00016 

Eureka,  Nev. 

Gold      

.00002 

Eureka,  Nev. 

Gold                

.00004, 

Owyhee  Co.,  Ido. 

It  is  quite  evident  that  the  percentage  of  metal  normally  dis- 
tributed in  the  rocks  of  the  earth's  crust,  as  indicated  above,  is 
far  too  low  to  be  regarded  as  workable  ore,  for,  in  order  to  be  classed 
as  such,  the  rock  must  contain  at  least  a  certain  percentage  of 
the  metal,  which  varies  not  only  with  the  metal,  but  even  with 
the  same  one  under  different  conditions,  such  as  location  and 
nature  of  ore. 

Iron  ores,  for  example,  especially  low-grade  ones,  cannot  be  suc- 
cessfully worked,  unless  favorably  located;  whereas  gold  ores, 
being  of  higher  unit  value,  are  much  less  affected  by  this  factor. 
Again,  the  nature  of  the  ore  has  to  be  considered,  some  being  quite 
easily  treated,  but  others  less  so,  and  here  the  manner  of  associa- 
tion comes  into  consideration.  Thus  the  presence  of  copper  or 


ORE   DEPOSITS  437 

lead  may  facilitate  the  extraction  of  gold  and  silver,  while  zinc 
hinders  it.  Lastly,  with  changed  conditions,  a  rock  which  was 
formerly  of  no  economic  value  may  become  a  profitable  ore  to 
work,  partly  because  improved  methods  of  treatment  have 
lowered  the  cost  of  production.  The  quantity  of  metal  necessary 
in  an  ore  for  profitable  working  is  referred  to  under  "  Value  of 
Ores  "  in  this  chapter. 

Source  of  Water  in  the  Earth's  Crust  (142,  143,  145,  147,  152).  — 
Water  is  known  to  be  widely  but  not  uniformly  distributed  in 
the  rocks  of  the  earth's  crust,  and  much  of  it  is  in  slow  but  con- 
stant circulation.  Geologists  admit  that  this  ground  water  has 
been  an  important  ore  carrier,  but  there  has  existed  a  strong 
difference  of  opinion,  regarding  its  source,  or  at  least  the  source 
of  that  portion  which  has  been  active  as  an  ore  carrier. 

Three  types  of  ground  water  are  recognized,  viz.  (1)  Meteoric, 
(2)  Connate  and  (3)  Juvenile. 

Meteoric  Water.  —  A  variable  portion  of  the  rain  falling  on  the 
earth's  surface  penetrates  the  pores  and  other  cavities  of  the 
regolith  and  bed  rock,  forming  a  more  or  less  saturated  zone, 
wrhose  upper  limit  is  known  as  the  water-table.  While  the  latter 
follows  in  a  general  way  the  surface  contours,  it  may  approach 
close  to  the  surface  under  the  valleys,  and  lie  at  a  greater  depth 
below  the  hills.  In  moist  regions  the  average  depth  of  the  water 
table  is  shallow,  but  in  arid  regions  it  may  lie  deep,  sometimes 
2000  feet  or  more. 

Between  the  surface  and  the  water  table  is  a  zone  of  descending 
oxidizing  waters,  as  well  as  one  containing  altered  rocks  and 
minerals.  This  zone  has  been  variously  called  the  vadose  region 
(Posepny),  belt  of  weathering  (Van  Hise)  and  gathering  zone 
(Finch). 

Below  the  water  table,  the  meteoric  water  penetrates  to 
variable  but  probably  not  great  depths.  Some,  like  Van  Hise, 
believed  that  it  might  go  as  deep  as  cavities  existed,  in  other 
words  to  the  bottom  of  the  zone  of  fracture  or  cavities.  Hos- 
kins  figured  that  this  might  be  as  deep  as  10,000  meters,  but  the 
experiments  of  Adams  and  King  l  indicated  that  it  may  be  even 
deeper. 

The  last  named,  in  their  experiments,  subjected  granite  cylinders  with  a 
.05-inch  hole  bored  through  them  to  a  pressure  of  96,000  pounds  per  square 
inch,  and  a  temperature  of  550°  C.for  70  hours,  without  producing  any  change 

1  Jour.  Geol.,  XX:   119,  1912. 


438  ECONOMIC   GEOLOGY 

in  the  opening.  The  pressure  corresponded  to  that  which  would  exist  at  a 
depth  of  15  miles,  and  the  temperature  to  that  estimated  to  prevail  at  11  miles 
below  the  surface.  In  granitic  rocks  therefore  cavities  might  exist  at  the 
above  mentioned  depth. 

There  seems  strong  doubt,  however,  as  to  whether  surface 
waters  penetrate  to  any  such  depth,  for  observations  in  mines  not 
only  indicate  frequently  a  decrease  in  water  with  depth,  but  the 
bottoms  of  some  deep  ones  are  dry  and  dusty. 

Finch  suggests  dividing  the  water  below  the  water  table  into 
two  zones.  The  upper  one  he  calls  the  discharge  zone,  and  in  this 
the  water  is  in  lateral  motion  toward  some  lower  discharge  level. 
The  lower  is  called  the  static  zone,  and  in  this  the  water  is  sta- 
tionary or  nearly  so. 

Attempts  have  been  made  to  estimate  the  quantity  of  water  in  the  outer 
part  of  the  earth's  crust,  the  amount  being  expressed  in  terms  of  thickness  of 
a  sheet  of  water  covering  the  earth's  surface.1 

These  estimates  by  different  authors  are: 

Delesse,  1861,  7500  feet. 

Slichter,  1902,  3000-3500  feet. 

Chamberlin  and  Salisbuiy,  1903,  800  fest.    . 

Chamberlin  and  Salisbury,  1903,  1600  feet  (on  another  assumption). 

Van  Hise,  1904,  226  feet. 

Fuller,  1906,  96  feet. 

The  later  estimates,  which  are  probably  more  exact,  indicate  a  rather 
shallow  depth,  and  indicate  the  impossibility  of  assuming  meteoric  waters 
to  be  genetic  factors  in  the  formation  of  deep  veins. 

That  meteoric  waters  were  the  most  important,  if  not  the  only 
collecting  agents  of  ores,  was  advocated  by  many  of  the  earlier 
geologists,  including  J.  Le  Conte,2  F.  Posepny,3  and  L.  De  Launay,4 
while  in  recent  years  this  theory  of  ore  formations  has  been  strongly 
urged  by  Van  Hise  (12). 

There  is  no  doubt  that  the  circulation  of  meteoric  waters  is 
quite  extensive,  and  it  plays  an  important  role  in  the  secondary 
concentration  of  ores,  by  downward-moving  solutions,  but  its 
effects  as  a  factor  in  the  primary  concentration  of  ore  deposits 
are  probably  unimportant  except  in  a  few  regions. 

Connate  Water  (147) . — This  is  water  which  is  indigenous  to  the 
rocks  containing  it,  such  as  original  sea-water  in  a  sedimentary 

1  Fuller,  Water  Supply  Paper,  160:   59,  1906. 

2  Amer.  Jour.  Sci.,  July,  1883,  p.  1. 

3  Trans.  Amer.  Inst.  Min.  Engrs.,  XXIII,  p.  213. 

4  La  Recherche,  Captage,  et  Amenagement  des  Sources  Thermo-Minerales. 


PLATE  XXXIX 


FIG.  1.  —  Specimen  from  Moresnet,  Belgium,  showing  crustified  structure.  Light 
bands,  sphalerite  (AS)  ;  Dark  bands,  pyrite  (M) ;  Light  grains,  galena  ((?) . 
(From  specimen  in  Cornell  collection.) 


FIG.  2.  —  Steamboat  Springs,  Nev.  The  white  deposit  is  siliceous  sinter  carrying 
mercury  and  antimony.  Steam  rises  from  numerous  fissures  whose  sides  are 
coated  with  sulphur  crystals.  (H,  Ries,  photo.) 

(439) 


440  ECONOMIC   GEOLOGY 

rock  or  magmatic  water  in  an  igneous  rock.  In  the  former  it  is 
found  chiefly  in  sandstones  and  sands,  the  brines  of  the  Lower 
Carboniferous  and  some  other  formations  being  examples  of  it. 

Igneous  rocks  may  retain  some  of  their  magmatic  waters  on 
consolidation,  and  it  is  possible  that  some  of  the  changes 
which  go  on  in  them  after  solidification  depend  on  this  residual 
liquid  (13). 

Submarine  lava  flows  may  absorb  ocean  water,  and  that  found 
in  some  deeply-buried  lava  flows,  as  those  of  the  Keweenaw  pen- 
insula of  Michigan,  may  be  of  this  nature.  Lane  (1  8),  in  his 
Lake  Superior  work,  has  called  attention  to  the  relatively  large 
calcium  chloride  content  of  the  copper-mine  waters  at  depths  of 
600  to  1600  feet,  and  believes  that  it  must  be  of  marine  origin. 
In  fact,  both  sodium  and  calcium  chlorides  are  in  evidence  with 
depth,  the  former  preponderating  at  first,  but  deeper  down  yield- 
ing to  the  latter. 

Magmatic  Water  (40,  75,  80,  83,  130,  145,  147,  152).  — The 
majority  of  geologists  now  believe  that  the  primary  concentra- 
tion of  ores  has  in  most  cases  been  performed  by  magmatic  waters. 

This  theory,  although  it  has  grown  greatly  in  recent  years, 
is  not  a  new  one,  for  it  was  suggested  by  Elie  de  Beaumont  as 
early  as  1850  j1  but  its  full  significance  was  not  grasped  until 
some  years  later,  when  the  writings  of  Vogt  2  (in  1894),  Spurr,3 
Lindgren,  and  especially  Kemp  (80)  did  much  to  emphasize  its 
importance. 

The  general  .theory  is  that  deep-seated  masses  of  igneous  rock 
have  dissociated  water  as  well  as  other  gaseous  elements,  the 
water-  and  gas-filled  cavities  in  quartz  indicating  this.  In 
addition,  there  may  also  be  chemically  combined  water.  As 
the  magma  solidified,  the  water  (probably  in  gaseous  form)  was 
expelled,  carrying  along  dissolved  substances. 

Some  have  claimed,  of  course,  that  the  water  contained  within 
the  magma  may  have  come  .from  external  sources  in  at  least  two 
ways  as  follows:  1.  By  infiltration  of  sea-water  to  the  igneous 
mass,  a  somewhat  unlikely  process,  as  the  heat  would  drive  it 
out.  2.  By  the  absorption  of  hydrated  rocks,  which  became 
engulfed  in  the  rising  magma  as  it  forced  its  way  upward,  a 
phenomenon  regarding  which  field  evidence  is  lacking. 

1Geol.  Soc.  France,  Bull.  IV:   1249. 

2  Zeitschr.  fiir  prak.  Geol.  II. 

8  U.  S.  Geol.  Surv.,  16th  Ann.  Kept.,  II. 


ORE   DEPOSITS  441 

One  thing  seems  certain,  and  that  is,  that  the  igneous  rocks 
give  off  water  in  vaporous  form  during  cooling.  Evidence  of 
its  presence  is  found  in  volcanic  emanations,  as  most  convincingly 
shown  by  Day  and!  Shepherd  (39),  by  the  analyses  published 
by  F.  C.  Lincoln  (40),  and  the  work  of  R.  T.  Chamberlin.1  As 
against  this  evidence  there  is  the  statement  of  P.  Brun  (37), 
based  on  possibly  insufficient  field  data,  that  water  is  not  given 
off  by  magmas. 

Many  of  the  points  brought  out  by  the  advocates  of  magmatic 
waters  as  ore-concentrating  agents  have  been  used  as  arguments 
against  the  possible  efficiency  of  meteoric  ones.  These  include 
the  following :  Meteoric  waters  do  not  reach  great  depths,  in  fact 
probably  not  more  than  2000  feet  or  sometimes  less  from  the 
surface,  and  when  they  do  penetrate  to  a  greater  distance,  it  is 
because  they  have  followed  some  fissure.  The  lower  levels  of 
many  deep  mines  are  so  dry  as  to  be  dusty.  Ores  have  been  con- 
centrated at  a  much  greater  depth  than  that  reached  by  surface 
waters.  It  is  perfectly  reasonable  to  regard  igneous  rocks  as 
an  important  source  of  water,  and  the  experiments  of  Daubree 
have  shown  that  a  molten  granite  contains  a  large  amount  of 
vapor  which  it  retains  while  at  great  depths,  but  gives  off  on 
approaching  the  surface  and  cooling. 

It  is  an  undeniable  fact  that  most  metalliferous  veins  are  found 
in  areas  of  igneous  rocks,  and  Lindgren  (see  Metallogenetic  Epochs 
on  a  later  page)  has  shown  that  in  the  case  of  the  gold  deposits 
of  North  America  the  periods  of  vein  formation  agreed  closely 
with  those  of  igneous  activity.  It  is  also  a  noteworthy  fact  that, 
with  the  exception  of  some  deposits  of  commoner  metals,  such  as 
some  iron,  copper,  lead,  and  zinc,  ores  are  found  in  close  associa- 
tion with  igneous  intrusions,  which  seems  to  postulate  a  close 
connection  between  igneous  rocks  and  ore  deposits,  as  advocated 
by  such  authorities  as  Weed,  Kemp,  Lindgren,  and  Emmons. 
While  the  importance  of  magmatic  waters  as  agents  of  primary 
deposition  is  quite  generally  admitted,  it  is  true  that  the  metallif- 
erous minerals  as  originally  deposited  have  not  always  been 
sufficiently  concentrated  to  serve  as  ores,  but  they  have  become 
concentrated  at  a  later  date  by  meteoric  waters,  as  at  Bisbee, 
Arizona.  (See  Ransome,  under  copper  references.)  Posepny 
(84),  in  his  work  on  the  Genesis  of  Ore  Deposits,  distinguishes 
between  descending  surface  waters,  or  vadose  circulations,  and 

1  Carnegie  Institution,  1908. 


442  ECONOMIC  GEOLOGY 

ascending  waters  from  great  depths.     It  is  the  former  that  have 
been  active  in  the  secondary  concentration  of  ores. 

Composition  of  Ground  Waters  (5, 13, 140,  142, 147). — The  ground 
waters  show  a  variable  temperature  and  always  a  variable  quan- 
tity of  dissolved  matter. 

The  waters  of  sedimentary  rocks,  beyond  the  influence  of  igne- 
ous intrusions,  are  mainly  of  carbonate  character.  In  chloride 
waters,  sodium  and  calcium  are  prevalent,  and  even  calcium 
and  sulphate  ones  are  not  uncommon,  but  sodium  carbonate 
waters  are  rare  in  mining  regions.  The  waters  are  chiefly  cold, 
although  many  tepid  ones,  and  even  some  hot  ones  occur.  Both 
hydrogen  sulphide  and  carbon  dioxide  may  be  present  in  either 
hot  or  cold  waters. 

In  the  older  igneous  rocks,  where  the  effects  of  vulcanism  have 
subsided,  there  is  less  variation.  The  surface  waters  in  these, 
where  free  from  disturbing  influences,  are  of  the  calcium  car- 
bonate type,  but. may  often  show  sodium  chloride,  ferrous  and 
magnesium  carbonates,  and  even  much  silica.  If  the  rocks 
contain  pyrite,  sulphuric  acid  may  be  present  locally,  together 
with  sulphate  of  lime,  alumina  and  iron. 

Ascending  waters  in  igneous  rocks  of  recent  or  Tertiary  volcanic 
activity  are  often  tepid  or  hot.  They  may  carry  sodium  chloride, 
or  sodium  carbonate  with  carbon  dioxide. 

Mine  Waters  (110,  140,  146,  148).  —  These  are  usually  surface 
waters,  whose  composition  is  modified  by  the  presence  of  soluble 
salts  derived  from  the  decomposing  minerals  of  the  ore  body,  or 
igneous  sources.  They  may  therefore  contain  both  metallic  and 
non-metallic  elements,  and  show  the  power  of  water  to  transport 
different  elements  in  solution.  The  analyses  on  page  443  will 
serve  for  purposes  of  illustration. 

Metalliferous  Deposits  from  Springs  (141,  149,  150,  153).- 
The  composition  of  many  spring  waters  also  affords  further 
testimony  of  the  ability  of  underground  waters  to  serve  as  ore 
carriers.  Moreover,  occasional  examples  of  metalliferous  deposits 
now  being  formed  by  springs  are  sometimes  found  as  shown 
below. 

Weed  has  described  a  hot  spring  near  Boulder,  Montana  (153), 
which  is  depositing  auriferous  quartz,  and  the  deposit  is  pointed 
out  by  him  to  be  identical  with  silver-  and  gold-bearing  quartz 
veins  of  the  region  between  Butte  and  Helena,  Montana.  Of 
still  more  interest  is  the  collection,  by  evaporation,  of  copper 


ORE   DEPOSITS 


443 


ANALYSES  OF  MINE  WATERS 
(Parts  per  million) 


I 

II 

III 

IV 

SO4              .... 

406.5 

2672 

43.2 

2039  51 

Cl 

6.8 

13 

7  9 

8  16 

CO3     

13.2 

110.5 

NO, 

PO4 

tr. 

tr. 

tr. 

B/)T 

tr. 

Br 

tr 

F    .    



tr. 





SiO2    

23.2 

47.7 

25.9 

43.80 

K             

7.1 

13.1 

10.6 

70.0 

Na                .... 

16.2 

39.6 

36.4 

106.27 

Li  

tr. 

tr. 

Ca            

151.2 

132.5 

37.4 

187.15 

Me 

28.2 

61.6 

12.25 

93.50 

Al 

83  5 

0  4 

3  12 

Mn      

0.5 

12.0 

0.8 

155.58 

Ni 

\ 

Co 

0.5 

• 



Cu      

tr. 

59.1 

tr. 

77.05 

Zn 

0.3 

852 

0.2 

49.66 

Ye'"    

\ 

Fe"         

}       1.8 

159.8 

0.7 

164.82 

Prl 

41  1 

Pb          

, 

tr. 

3.44 

CO2     . 



37.2 

I.  Green  Mountain  Mine,  Butte,  Mont.,  220-foot  level  fissure  in  granite, 
remote  from  known  veins;  II.  St.  Lawrence  Mine,  Butte,  Mont.;  III.  Geyser 
Mine,  Custer  Co.,  Col.;  IV.  Stanley  Mine,  Idaho  Springs,  Col.  All  quoted 
by  Emmons,  U.  S.  Geol.  Surv.,  Bull!  529,  pp.  60,  62  and  63,  1913. 

from  certain  Javan  hot  springs,  in  which  the  metal  occurs  as 
iodide  of  copper.1 

Lindgren  has  also  recently  called  attention  to  the  occurrence 
of  certain  mineral  springs  near  Ojo  Caliente,  New  Mexico  (150), 
whose  strongly  alkaline  water  contains  much  sodium  carbonate 
as  well  as  fluorine,  boron,  and  barium,  the  last  being  present  in 
considerable  amount. 

The  pre-Cambrian  gneiss  near  by  contains  veinlets  of  colorless 

Stevens,  Copper  Handbook,  IV:   156,  1904. 


444  ECONOMIC   GEOLOGY 

fluorite,  probably  deposited  when  the  spring  waters  issued  at  a 
higher  level.  Higher  up  the  slope  is  a  narrow  vein,  carrying  small 
amounts  of  gold  and  silver  in  a  gangue  of  colorless  fluorite  and 
some  barite,  and  capped  by  a  calcareous  tufa.  The  latter  is  sup- 
posed to  have  been  deposited  at  the  surface  while  the  fluorite 
was  precipitated  farther  down  in  the  vein  fissure. 

At  Steamboat  Springs,  Nev.,  the  hot  chloride  waters  are  deposit- 
ing siliceous  sinter  (Plate  XXXIX,  Fig.  2),  which  contains  mer- 
cury and  antimony  in  small  amounts,  while  stibnite  crystals  have 
been  found  in  some  of  the  spring  basins. 

Mode  of  Concentration.  —  From  what  has  been  said  above  we 
see  that  water  is  not  only  widely  distributed  in  the  rocks,  but  also 
serves  as  a  carrier  of  mineral  matter.  It  is,  therefore,  an  impor- 
tant concentrating  agent,  whatever  its  source.  While  cold  water, 
free  from  impurities,  has  comparatively  little  solvent  power, 
the  presence  of  acids  or  alkalies  materially  increases  its  solvent 
capacity,  while  heat  and  pressure  have  also  a  great  influence. 

Before  considering  the  causes  governing  the  precipitation  of 
ore  minerals  in  cavities  or  solid  rocks,  we  may  turn  to  a  discussion 
of  the  deposits  formed  by  waters  of  magmatic  origin. 

Deposits  from  Magmatic  Emanations.  —  Under  magmatic  ema- 
nations are  included  gases,  vapors,  or  liquids,  given  off  by  molten 
magmas  during  cooling. 

These  emanations  (37-40),  may  be  determined  from  those 
actually  in  process  of  emission  from  cooling  igneous  magmas,  or 
from  those  which  remain  imprisoned  in  the  rocks. 

As  evidence  of  the  variety  of  the  former  we  may  list  the  following  ema- 
nations identified  at  two  well-known  volcanoes: 

Vulcano,  S,  Te,  As  S  ,  B2O3,  NaCl,  NH4C1,  FeCl3,  Na2SO4-CaSO4,  Li2(SO4)3, 
A12(SO4)3,  Tl,  Rb,  Ce,  Co,  Zn,  Sn,  Bi,  Pb,  Cu,  I,  P. 

Vesuvius,  1895.  HC1,  SO2,  H2S,  CO2,  S,  CaSO4,  iron  and  copper  chlorides, 
NaCl,  KC1,  Na2S04,  K2SO4,  NH4C1,  CuO,  Fe2O3,  Se,  HF,  HBr,  NaHCO3. 

The  springs  of  Carlsbad,  Bohemia,  which  are  supposed  to  be  or  magmatic 
derivation  show  CO2  and  salts  of  the  elements  Cl,  F,  B,  P,  S,  Se,  Tl,  Rb,  Cs, 
As,  Sb,  Zn,  Na,  K,  Li,  Ca,  Mg,  Sr,  Ba,  Fe,  Mn,  Al  and  Si. 

In  order  to  point  out  more  clearly  the  several  processes  by  which 
ores  may  be  deposited  from  magmatic  emanations  it  may  be  well 
to  turn  for  a  moment  to  the  molten  magma  and  consider  certain 
changes  which  take  place  during  the  period  referred  to. 

A  study  of  large  intrusive  masses  has  shown  us  that  the  molten 
mass  after  coming  to  rest  sometimes  tends  to  separate  into  two 


ORE   DEPOSITS  445 

parts,  the  one  basic,  the  other  acid,  with  a  gradational  zone  be- 
tween. The  acid  portion  may  be  either  the  outer  or  central  part 
of  the  mass. 

A  segregation  of  metallic  minerals  may  occur,  even  if  the 
magma  as  a  whole  does  not  split  up.  But  whether  or  not  such 
a  differentiation  occurs,  the  molten  magma,  after  coming  to  rest, 
will  cool  first  in  its  outer  and  upper  portion,  the  contraction  inci- 
dent to  solidification  causing  numerous  fractures.  Into  these  there 
may  be  forced  molten  rock  from  the  still  uncooled  lower  portions 
of  the  mass,  or  water  and  gases  forced  out  of  the  solidifying  parts 
of  the  magma.  This  water,  however,  must  be  in  a  vaporous  form, 
because  the  heat  is  undoubtedly  sufficiently  great  to  raise  its  tem- 
perature above  the  critical  point,  and  the  pressure  is  likewise  heavy. 
In  many  cases  no  doubt  the  fissure  may  become  filled  by  a  mixture 
of  water  and  magma,  the  former  in  such  excess  that  it  may  be  diffi- 
cult to  say  whether  this  should  be  called  an  igneous  fusion,  or  a 
watery  solution,  for  under  pressure  water  can  mix  with  a  magma, 
in  all  proportions,  giving  us  a  series  of  mixtures,  with  a  fused  mass 
at  one  end  and  a  hot  solution  at  the  other. 

Many  magmas  in  cooling  give  off  mixtures  of  watery  vapors 
and  gases  (such  as  fluorine,  boron,  etc.) ;  and  these  before  leaving 
the  igneous  mass  no  doubt  extract  metallic  or  other  elements  and 
carry  them  along,  only  to  deposit  them  later,  either  in  the  outer 
parts  of  the  cracks  in  the  border  of  the  intrusion  or  in  the  surround- 
ing rocks. 

As  these  emanations  from  the  magma  get  farther  away  from  it, 
where  temperature  and  pressure  are  less,  the  watery  vapors  con- 
dense, and  these  hot  solutions  (magmatic  or  juvenile  waters)  grad- 
ually work  their  way  towards  the  surface,  sometimes  reaching  it, 
and  flowing  out  as  hot  springs. 

It  is  possible  and  indeed  probable  that  as  they  reach  shallower 
depths  they  may  become  more  or  less  mixed  with  meteoric  waters. 

These  magmatic  emanations  with  their  burden  of  mineral  matter 
may  not  only  deposit  this  at  a  varying  distance  from  the  intrusive, 
but  they  in  many  cases  often  attack  the  rocks  through  which  they 
pass,  altering  them  to  a  marked  degree,  and  in  addition  dissolve 
materials  from  the  rocks  they  permeate. 

The  kind  of  materials  deposited  and  the  character  of  the  altera- 
tion depend  to  a  large  degree  upon  physical  conditions,  primarily 
temperature  and  pressure. 

If  the  deposition  and  alteration  occur  w^hile  the  magmatic  emana- 


446  ECONOMIC   GEOLOGY 

tions  are  still  in  a  vaporous  form  (due  to  high  temperature  and 
pressure),  the  process  is  termed  pneumatolysis  (gaseous).  If  it 
occurs  when  the  water  is  in  liquid  form,  it  is  termed  hydatogenesis 
(aqueous).  In  some  instances  both  gases  and  liquids  may  be  pres- 
ent, the  work  then  being  gas-aqueous  or  pneumato-hydato-genetic. 

It  is  naturally  difficult  to  prove  in  many  cases  whether  the 
phenomena  observed  were  produced  by  pneumatolytic  or  hydato- 
genetic  processes. 

Certain  important  types  of  deposits,  formed  under  these  vary- 
ing physical  conditions,  may  now  be  referred  to. 

Pegmatite  Dikes1  (2,  13,20,  21).  —  The  last  unconsolidated 
portions  of  an  intrusive  magma  may  be  forced  out  from  the 
parent  mass  to  form  dikes.  These  dikes,  which  may  be  of  either 
basic  or  acid  character,  will  in  general  contain  the  same  constit- 
U3nts  that  are  present  in  the  parent  magma,  but  in  different 
proportions,  certain  residual  products  being  in  excess.  When 
coarse  grained  these  dikes  are  termed  pegmatites.  Basic  rocks 
like  gabbros  may  be  accompanied  by  pegmatites  containing 
chiefly  plagioclase  feldspar  and  pyroxene,  while  granites  are 
accompanied  by  those  consisting  chiefly  of  feldspar,  quartz  and 
muscovite,  as  well  as  cassiterite,  tourmaline,  topaz,  monazite, 
or  even  other  rare  minerals. 

An  important  feature  is  the  presence  of  volatile  substances, 
mineralizers  (including  watery  vapor),  which  tend  to  lower  the 
solidification  point  of  the  mass.  Indeed,  the  temperature  accord- 
ing to  Lindgren  may  be  lower  than  500°  C.,  and  this  combined  with 
the  fluidity  of  the  mass,  due  evidently  to  a  high  water  content, 
undoubtedly  permits  the  pegmatite  to  force  its  way  into  many 
rocks  along  the  separation  planes. 

Of  the  mineralizers,  fluorine  and  boron  seem  to  favor  acid 
pegmatites,  while  chlorine,  phosphorus  and  sulphur  are  present 
in  the  basic  ones. 

Pegmatite  dikes  form  an  interesting  and  important  link  in 
the  chain  of  magmatic  products,  and  while  rich  in  minerals,  are 
not  important  as  sources  of  the  ores.  They  have  been  worked 
for  cassiterite  as  in  South  Carolina  (Ref.  10,  Tin)  and  South 
Dakota  (Ref.  14,  Tin).  For  gold,  as  at  Silver  Peak,  Nev.  (Ref. 
92,  Gold) ;  for  bismuth  in  the  New  England  district  of  New  South 
Wales;  and  for  molybdenite  in  Norway.  New  South  Wales  and 
Queensland. 

1  See  Harker,  Natural  History  of  Igneous  Rocks,  p.  293. 


ORE  DEPOSITS  447 

High-Temperature  Veins.  —  These  form  a  series  related  in  a 
ivay  to  the  pegmatite  dikes.  The  latter  were  intrusions,  contain- 
ing so  much  water  as  to  be  classed  properly  as  aqueo-igneous 
fusions,  and  having  naturally  rather  sharply  denned  boundaries. 

The  high-temperature  veins  represent  magmatic  products 
forced  out  from  a  cooling  magma,  consisting  probably  of  a  mixture 
of  water  and  gases,  with  other  substances  in  solution,  the  whole 
being  under  high  pressure  and  temperature.  The  latter  is  proba- 
bly not  in  excess  of  575°  C.,  the  inversion  point  of  crystalline 
quartz,1  nor  is  it  supposed  to  have  been  below  300°  C.,  and  the 
water  being  heated  above  its  critical  temperature  was  undoubtedly 
in  a  vaporous  form. 

A  characteristic  feature  of  these  veins  is  the  frequently  intense 
metasomatic  alteration  of  the  wall  rock,  which  may  result 
in  the  conversion  of  the  latter  into  a  coarse-grained  mineral 
aggregate. 

The  evidence  of  these  conditions  is  shown  by  the  presence  of 
essentially  high-temperature  minerals  (p.  458),  some  of  which 
crystallize  only  in  the  presence  of  mineralizers.  These  include 
pyroxenes,  amphiboles,  garnets,  apatite,  ilmenite,  tourmaline, 
topaz,  brown  and  green  micas,  spinel,  soda-lime  feldspars,  cassiter- 
ite,  arsenopyrite,  pyrrhotite  and  some  others. 

The  veins  have  been  formed  at  great  depth,  and  while  in  some 
cases  they  are  close  to  the  intrusive,  or  even  within  it,  at  others 
they  may  be  some  distance  from  it,  but  still  initially  at  such 
depth  as  to  maintain  the  conditions  of  temperature  and 
pressure. 

Several  classes  of  veins  seem  to  belong  to  this  group,  as  follows: 2 

1.  Veins  of  cassiterite,  wolframite  and  molybdenum,  the  first  named  being 
specially  important. 

2.  Gold-bearing  veins  in  crystalline  schists  as  those  of  the  southern  Appa- 
lachians, southern  Brazil,  southeastern  Alaska,  Ontario,  Lead  City,  S.  Dak., 
and  Kalgoorlie,  W.  Australia. 

3.  Copper-gold-tourmaline  deposits,  represented    by  those  of  Cornwall, 
Eng.;  3  Cactus  Mine,  Utah;  Rossland,  British  Columbia;  and  Meadow  Lake, 
Calif. * 

1  F.  C.  Wright  and  E.  S.  Larsen,  Quartz  as  a  Geologic  Thermometer,  Amer. 
.Jour.  Sci.,  XXVII:   147,  1909. 

2  Those  not  referred  to  in  the  following  footnote  are  discussed  in  subsequent 
chapters  on  those  metals. 

3  Vogt,  Krusch  and  Beyschlag,  Ore  Deposits,  Translation,  I:  431. 
4Lindgren,  Amer.  Jour.  Sci.,  XLVI:  201,  1893. 


448 


ECONOMIC  GEOLOGY 


4.  Lead-silver    tourmaline  veins    associated   with  the   Helena  batholith, 
Montana.1 

5.  Cobalt-tourmaline  veins  of  San  Juan,  Chile.2 

Contact-Metamorphic  Deposits  (24-36).  —  These  include 
masses  of  metallic  minerals  and  silicates  which  are  found  in  some 
sedimentary  rocks,  chiefly  calcareous  ones,  near  their  contact  with 
igneous  intrusions,  specially  those  of  a  more  or  less  acidic  char- 
acter (Fig.  136). 

It  has  long  been  known  that  an  igneous  mass  may  often  exert 
considerable  effect  on  the  rocks  which  it  has  penetrated,  sandstone, 


FIG.  136.  —  Section  through  a  contact-metamorphic  zone;  showing  (a)  intrusive 
rock;  (6)  quartzite ;;(  (c)  limestone;  (d)  shale.  Contact-metamorphic  zone 
shown  in  stippled  area,  including  ore  in  black.  (From  Ries  and  Watson, 
Engineering  Geology.) 

for  example,  being  altered  to  quartzite,  clay  or  shale  to  hornstone, 
and  limestone  to  marble.  Moreover,  the  contact-metamorphism 
is  accompanied  by  the  development  of  new  minerals  in  the  wall 
rock. 

Thus  in  limestone  there  may  be  formed  garnet,  wollastonite, 
epidote,  diopside,  amphibole,  wernerite,  vesuvianite,  etc.;  while 
in  aluminous  rock  such  as  shale  and  slate  we  find  andalusite,  silli- 
manite,  biotite,  etc. 

It  was  formerly  believed  by  many  that  these  silicates,  as  in 
the  limestones,  must  be  segregated  and  recrystallized  impuri- 

1  Knopf,  Econ.  Geol.,  VIII:    105,  1913. 
2Stutzer,  Zeitschr.  prak.  Geol.,  XIV:   294,  1906. 


ORE   DEPOSITS  449 

ties,  and  hence  could  form  only  in  impure  rocks,  the  pure  lime- 
stones yielding  simply  a  marble. 

Investigation  of  these  contact  zones  has  shown  us,  however, 
that  they  contained  many  elements  which  were  not  found  in  the 
limestone  outside  of  this  belt  of  metamorphism,  and  we  are 
therefore  driven  to  the  conclusion  that  they  represent  substances 
which  have  been  given  off  by  the  magma  and  lodged  in  the  lime 
rock. 

The  theory  usually  advanced  to  explain  the  origin  of  these 
contact-metamorphic  deposits,  is  that  the  original  magma  con- 
tained various  volatile  substances  in  solution,  such  as  water, 
carbon  dioxide,  sulphur,  boron,  chlorine,  and  fluorine,  which  on 
the  cooling  and  solidification  of  the  magma  are  forced  out  into  the 
surrounding  rocks.  The  watery  vapor  was  evidently  heated 
above  its  critical  temperature  (365°  C.). 

The  metals  and  many  of  the  other  elements  found  in  contact 
metamorphic  deposits  are  supposed  to  have  been  carried  out  by 
these  vapors,  but  their  exact  form  of  combination  during  emission 
is  not  known,  although  it  has  been  suggested  that  some  were 
combined  with  fluorine  or  boron. 

These  were  forced  out  into  the  fissures  or  pores  of  the  lime- 
stone, and  replaced  the  latter  wholly  or  in  part,  the  silica,  alumina 
and  iron  combining  with  some  of  the  lime  to  form  different  sili- 
cates. 

While  contact-metamorphic  effects  may  extend  to  a  distance 
of  1  to  2  miles  from  the  eruptive,  ore  deposits  rarely  extend  more 
than  a  few  hundred  feet,  and  often  terminate  suddenly. 

Normal  granites  or  other  highly  acid  intrusives  may  produce 
contact  metamorphism,  but  do  not  as  a  rule  form  ore  deposits. 
Intrusives  like  monzonite,  quartz  monzonites  or  granodiorites 
are  important  associates  of  contact-metamorphic  ores,  as  can  be 
seen  by  the  numerous  occurrences  in  the  Cordilleran  region  of 
the  United  States.  The  more  basic  rocks  are  of  less  importance, 
although  they  sometimes  yield  contact-metamorphic  ores  in 
limestones  as  in  the  case  of  gabbro  at  Hedley,  British  Columbia, 
and  diabase  at  Cornwall,  Pennsylvania. 

Contact-metamorphic  deposits  were  probably  formed  at  depths 
of  several  thousand  feet,  and  possibly  in  most  cases  within  the 
zone  of  fracture.  The  temperature  according  to  Lindgren  was 
probably  high,  from  300°  C.  to  600°  C. 

Contact-metamorphic  deposits  are  usually  of  irregular  shape 


450  ECONOMIC   GEOLOGY 

and  somewhat  bunchy  in  character,  but  very  little  can  be  said 
regarding  the  depth  to  which  they  may  extend.  Where  the 
development  has  followed  certain  beds  a  tabular  structure  often 
results. 

The  common  ore  minerals  found  are  magnetite  and  specularite, 
together  with  such  sulphides  as  bornite,  chalcopyrite,  pyrite, 
pyrrhotite,  and  more  rarely  galena  and  zinc  blende.  Some  gold 
and  silver  may  be  present,  but  tellurides  are  probably  very  rare. 
Molybdenite  and  tetrahedrite  are  known. 

The  gangue  minerals  are  in  general  lime-alumina  silicates, 
and  include  garnet 1  (Fig.  137),  wollastonite,  epidote,  tremolite, 


FIG.  137.  —  Section  of  garnetiferous  limestone  from  Silver  Bell,  Ariz.     Dark  gray, 
garnet;   black,  sulphides. 

diopside,  hedenbergite,  zoisite,  vesuvianite,  ilvaite,  quartz  and 
calcite.  The  first  of  these  is  especially  abundant  and  may  form 
nearly  the  entire  mass  of  the  rock.  There  may  also  be  present 
minerals  containing  boron,  fluorine,  and  chlorine,  such  as  axinite, 
tourmaline,  fluorite,  scapolite  and  danburite. 

Some  difference  of  opinion  exists  regarding  the  details  of  the 
contact-metamorphic  process. 

Thus,  while  most  geologists  are  agreed  that  most  of  the  con- 
stituents of  the  ore  body  are  derived  from  the  magma,  others  like 

1  Mainly  andradite,  the  iron-lime  garnet,  and  less  often  grossularite,  the  lime- 
alumina  garnet. 


ORE  DEPOSITS  451 

Leith,  while  admitting  some  magmatic  emanations,  hold  that  the 
silicate  gangue  minerals  are  mainly  the  result  of  the  recrystalliza- 
tion  of  original  constituents  of  the  limestones.  This  means  the 
removal  of  an  excess  of  certain  constituents  and  a  consequent 
reduction  of  volume,  a  fact  which  is  said  not  to  be  proven  by  the 
field  evidence. 

In  strong  contrast  to  the  usually  accepted  theory  of  the  forma- 
tion of  contact-metamorphic  deposits,  is  that  advanced  and 
energetically  defended  by  A.  C.  Lawson  (30),  who  contends  that 
they  originate  by  the  action  of  meteoric  waters.  According  to 
him  any  circulation  of  groundwater  will  be  profoundly  disturbed 
by  igneous  injections  into  sedimentary  terranes.  As  a  result 
of  this  there  would  be  developed  an  upward  circulation  following 
along  the  periphery  of  the  heated  mass,  and  competent,  he  con- 
siders, to  form  the  characteristic  lime-silicate  zones.  Fractures 
in  the  country  rock  caused  by  the  igneous  intrusion,  or  shrinkage 
cracks  in  the  latter  due  to  crystallization  or  cooling,  would  afford 
channelways  for  the  rising  waters,  and  these  by  bringing  in 
material  leached  from  the  surrounding  region,  or  by  additional 
leaching  of  the  intrusive,  could  deposit  these  in  the  area  referred 
to  usually  as  the  contact-metamorphic  zone. 

W.  O.  Crosby  has  also  suggested  that  contact-metamorphic 
deposits  are  the  work  of  meteoric  waters  (26),  while  Klockman 
believes  that  they  represent  pre-existing  ore  bodies  altered  by 
intrusives  (29). 

Other  divergent  views  refer  to  the  question  of  whether  or  not 
the  magma  was  consolidated  before  mineralization  began.  Some 
writers  consider  that  the  metamorphism  of  the  limestone  occurred 
first,  followed  by  mineralization. 

The  order  of  succession  of  the  minerals  is  certainly  not  always 
the  same,  and  according  to  different  observers  the  sulphides  some- 
times follow  the  silicates,  or  at  other  times  are  contemporaneous 
with  them. 

Contact-metamorphic  deposits,  though  sometimes  rich  enough 
to  mine  where  not  secondarily  enriched,  need  this  process  in  many 
cases  to  make  the  ore  workable.  This  was  well  illustrated  in 
the  case  of  the  Morenci,  Arizona,  copper  ores. 

Although  this  class  of  deposits  was  recognized  by  von  Groddeck, 
as  early  as  1879,  he  failed  to  appreciate  the  true  importance  of 
the  associated  intrusive.  In  more  recent  years  the  writings  of 
Vogt,  Kemp,  Weed,  Lindgren,  and  Barrell  have  greatly  increased 


452  ECONOMIC   GEOLOGY 

our  knowledge  of  the  true  nature  of  these  interesting  deposits,  and 
we  now  know,  moreover,  that  they  form  a  very  important  and 
somewhat  common  type,  which  in  the  United  States  is  restricted 
mainly,  however,  to  the  Pacific  Cordilleras.  They  are  also 
known  in  Canada,  the  Yukon,  Alaska,  and  many  other  coun- 
tries. 

Contact  metamorphic  deposits  may  be  classified  as  follows  (13): — • 

1.  Magnetite  deposits. 

Examples:  Iron  Springs,  Utah,  l  Fierro,  N.  Mex.,2  and  Cornwall,  Pa.3 

2.  Chalcopyrite  deposits.     Chief  ore  minerals,  chalcopyrite,  pyrite,  pyr- 
rhotite,  sphalerite,  molybdenite  and  specularite. 

Examples:    Clifton,  Adz.,4  San  Pedro,  N.  Mex.,6  and  Cananea,  Mex.6 

3.  Galena-blende  deposits. 

Examples:   Magdalena  Mines,  N.  Mex.7 

4.  Arsenopyrite-gold  deposits.      Chief  minerals,    arsenopyrite    and    pyr- 
rhotite. 

Examples:  Hedley,  Brit.  Col.8 

5.  Gold  deposits. 

Examples:  Cable  Mine,  Mont.9 

6.  Cassiterite  deposits. 

Examples:  Pitkaranta,  Finland,10  Seward  Peninsula,  Alas.11 

Ore  Deposits  Formed  at  Intermediate  Depths. — Following  the 
succession  of  deposits  formed  under  conditions  of  gradually  de- 
creasing temperature  and  pressure,  there  has  been  recognized 
another  group  formed  presumably  at  intermediate  depths,  de- 
posited by  ascending  hot  waters,  and  evidently  genetically  con- 
nected with  intrusive  rocks. 

It  is,  of  course,  difficult  to  tell  the  exact  depth  of  their  forma- 
tion, which  Lindgren  has  estimated  within  a  somewhat  wide 
range  of  4000  to  12,000  feet;  but  it  can  sometimes  be  approxi- 
mately judged  by  determinating  the  thickness  of  overlying  rock 
removed  by  erosion.  An  important  character  of  these  deposits 
is  the  absence  of  high-temperature  minerals. 

1  Leith  and  Harder,  U.  S.  Geol.  Surv.,  Bull.  338,  1908. 

2  Graton,  Ibid.,  Prof.  Pap.  68:  313. 

3  Spencer,  Ibid.,  Bull.  430. 

4  Lindgren,  Ibid.,  Prof.  Pap.  43,  1905. 

5  Lindgren  and  Graton,  Ibid.,  Prof.  Pap.  68. 

6  Emmons,  S.  F.,  Econ.  Geol.,  IV:   312,  1910. 

7  Lindgren,  U.  S.  Geol.  Surv.,  Prof.  Pap.  68:   241. 

8  Camsell,  Can.  Geol.  Surv.,  Mem.  2,  1910. 

9  Emmons,  W.  H.,  U.  S.  Geol.  Surv.,  Bull.  315:  45,  1907. 

10  Vogt,  Krusch  and  Beyschlag.     Lagerstatten. 

11  Knopf,  U.  S.  Geol.  Surv.,  Bull.  358,  1908. 


ORE   DEPOSITS  453 

The  deposits  are  often  fissure  veins  or  a  related  type,  and  while 
the  minerals  frequently  fill  open  fissures,  replacement  deposits 
are  not  uncommon,  and  where  limestone  is  the  country  rock, 
may  be  of  considerable  extent. 

The  most  important  metals  in  these  deposits  are  gold,  silver, 
copper,  lead  and  zinc,  but  the  deeper-formed  members  of  the 
series  may  carry  molybdenum,  bismuth,  tungsten  and  arsenic. 
Sulphides,  arsenides,  sulpharsenides  and  sulphantimonides  are 
the  prominent  compounds,  while  oxides  are  rare.  Quartz  is 
the  chief  gangue  mineral,  but  carbonates  are  common. 

The  country  rock  usually  shows  intense  alteration  next  to  the 
ore,  feldspathic  and  ferromagnesian  rocks  yielding  sericite, 
carbonates  and  pyrite,  and  calcareous  rocks  often  showing  silici- 
fication.  The  last-named  process  may  also  be  accompanied*  by 
dolomitization. 

The  following  types,  with  examples  added,  may  be  enumerated  as  be- 
longing to  this  class: — 

1.  Gold  quartz  veins  of  California  and  Victoria  type.  Sierra  Nevada,1 
Inteiior  Cordilleran  region;1  Victoria,  Australia,1  and  Nova  Scotia.1 

2.  Gold-bearing  replacements  in  limestone.      Mercur,  Utah;1     siliceous 
gold  ores  of  Black  Hills,  S.  Dak.1 

3.  Gold-bearing  replacements  in  quartzite.     Delamar  Mine,  Nevada.2 

4.  Gold-bearing  replacements  in  porphyry.  '•  Cripple    Creek,  Colo,   (in 
part).     Little  Rocky  Mountains,  Montana.3 

5.  Silver-lead  veins,  including 

a.  Quartz-tetrahedrite-galena  veins.     Organ,  N.  Mex.4 

6.  Tetrahedrite-galena-siderite  veins.     Wood  River,  Idaho.5 

c.   Galena-siderite  veins.     Cceur  d'Alene,  Idaho.6 

6.  Lead-silver  veins  with  calcite,   siderite  and  barite.     Clausthal,  Ger- 
many and  Przibram,  Bohemia.6 

7.  Pyri tic-galena-quartz     veins.     Freiberg,7     Saxony;      Cerbat     range, 
Arizona.8 

8.  Silver-lead    replacements    in    limestones.     Aspen 6    and    Leadville, 
Colo.;7  Eureka,  Nev.;6  Lake  Valley,  N.  M.;  6  Park  City  and  Tintic,  Utah;« 
Sierra  Mojada,  N.  Mex.6 

9.  Tungsten  veins.     Boulder  County/,  Colo.9 

1  See  references  under  Gold. 

2  Emmons,  S.  F.,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXXI:  658, 1901. 
8  Emmons,  W.  H.,  U.  S.  Geol.  Surv.,  Bull.  340:   98,  1908. 

4  Lindgren  and  Graton,  U.  S.  Geol.  SurV.,  Prof.  Pap.  68:   209. 
6  Lindgren,  Ibid.,  20th  Ann.  Kept.,  Pt.  3:   190,  1900. 

8  See  under  Lead-Silver  ores. 
*  See  under  Lead-Silver  ores. 

«  Schrader,  U.  S.  Geol.  Surv.,  Bull.  397,  190Q. 

9  See  under  Tungsten. 


454  ECONOMIC   GEOLOGY 

10.  Native  silver  veins.     With  cobalt  and    nickel  as  at  Cobalt,  Ont.,1 
and  Annaberg,  Saxony;1  with  zeolites,  as  at  Kongsberg,  Sweden. 

11.  Copper  veins.     Butte,  Mont.,2  and  Virgilina,  Va.2 

12.  Pyritic    replacement    deposits.      Rammelsberg,    Harz;2     Mt.    Lyell, 
Tasmania;  2    Rio  Tinto,  Spain;2  Shasta  County,  Calif.;  2     Tyee,  Vancouver 
Island.2 

Ore  Deposits  Formed  at  Shallow  Depths  (13,  21) .  —  These  in- 
clude a  number  of  fissure-vein  deposits,  found  in  the  Cordilleran 
region,  and  carrying  gold  with  much  silver,  as  well  as  subordinate 
amounts  of  lead,  zinc,  and  copper.  The  fact  that  they  are  found 
in  flows  of  volcanic  origin  indicates  their  formation  at  compara- 
tively shallow  depths,  that  is,  from  a  few  hundred  to  four  or  five 
thousand  feet.  They  include  most  of  the  veins  of  western  Nevada, 
the  San  Juan  region  of  Colorado,  Cripple  Creek,  Colorado  dis- 
trict, etc. 

Gold  and  silver  are  prominent,  although  the  former  is  more 
abundant  and  the  native  gold  usually  more  finely  divided. 

Like  the  deeper  veins,  they  may  carry  pyrite,  galena,  and  sphal- 
erite, but  in  addition  chalcopyrite,  arsenopyrite,  argentite,  and 
stibnite  are  characteristic  ore  minerals.  Quartz  is  a  common 
gangue  mineral,  and  calcite,  dolomite,  siderite,  barite,  and  fluorite 
are  also  found.  Adularia  is  also  widespread  as  a  gangue  mineral. 

Metasomatism  varies  somewhat  with  the  different  rocks.  In 
moderately  acid  rocks  sericitization  and  even  pyritization  seem 
to  be  common  near  the  vein,  and  propylitization3  farther  away. 
In  basic  igneous  rocks,  propylitization  may  extend  close  to  the 
vein,  but  sericitization  occasionally  takes  its  place.  Silicification 
of  the  wall  rock  may  occur,  especially  in  rhyolites  and  sometimes 
in  calcareous  rocks. 

A  change  in  the  character  of  the  vein  mineralization  is  some- 
times shown,  as  when  earlier  calcite  gangue  is  replaced  by  quartz 
and  adularia. 

Since  these  ores  are  of  shallow  origin,  they  are  formed  in  the 
zone  of  fracture,  and  are  therefore  found  filling  cavities  of  varied 
origin  and  wide  distribution. 

Deposits  formed  at  shallow  depths  may  be  separated  into  different  types 
as  follows:- 

1  See  under  Nickel-Cobalt. 

2  See  under  Copper. 

*  This  consists  in  the  development  of  chlorite  and  epidote  as  well  as  pyrite,  from 
dark  silicates,  and  the  breaking  down  of  feldspar  to  quartz,  chlorite,  and  epidote, 
the  rock  assuming  a  dull  green  color. 


ORE  DEPOSITS  455 

1.  Quicksilver  deposits.1 

2.  Stibnite  deposits.2 

3.  Gold-quartz  veins.3 

a.  In  andesite,  Brad,  Transylvania;  Hauraki  Peninsula,  N.  Z. 
6.  In  rhyolite.     De  Lamar,  Ido. 

4.  Argentite-gold-quartz  veins.3     Tonopah  and  Comstock  Lode,  Nev. 

5.  Argentite  veins.3     Pachuca  and  Guanajuato,  Mexico. 

6.  Gold-telluride  veins.3    Cripple  Creek,  Colorado. 

7.  Gold-selenide  veins.3     Republic,  Washington. 

8.  Base-metal  veins.3    San  Juan  region,  Colorado. 

9.  Gold-alunite  veins.3     Goldfield,  Nevada. 

Deposits  Formed  at  the  Surface  by  Hot  Waters   (83).  —  At 

or  near  the  surface  mineral  deposits  may  be  formed  by  hot  springs, 
but  they  are  not  usually  of  economic  importance. 

Such  springs  may  deposit  earthy  carbonates  as  sinter,  and  silica 
as  opal  or  chalcedony.  Ore  minerals  developed  under  these  con- 
ditions in  crystallized  form  are  stibnite,  marcasite,  and  cinnabar, 
but  other  sulphides  have  been  detected  by  chemical  means.  Cal- 
cite,  fluorite,  barite,  and  celestite  may  also  develop. 

According  to  what  has  been  said  above  there  is  a  somewhat 
continuous  series  of  deposits  from  the  deepest  to  the  higher  and 
cooler  zones,  the  mineral  combinations  gradually  changing  from 
those  of  magmatic  and  contact-metamorphic  conditions,  to  those 
known  to  exist  in  surface  hot  springs. 

Formation  of  Cavities.  —  The  deposition  of  ores  in  the  rocks  is 
greatly  facilitated  by  the  presence  of  cavities  along  which  the 
ore-bearing  solutions  freely  pass,  and  consequently  a  great  many 
ore  deposits  occur  in  such  spaces.  There  are  a  number  of  different 
ways  in  which  cavities  may  be  formed  in  rocks.  The  percolation 
of  surface  water  through  certain  ones,  such  as  limestones,  often 
results  in  the  formation  of  solution  cavities,these  in  many  instances 
attaining  the  size  of  veritable  caverns ;  a  soluble  rock  may  contain 
more  or  less  insoluble  material,  such  as  clay  or  chert,  which  col- 
lapses when  the  surrounding  rock  is  dissolved,  and  partly  fills  the 
cave  thus  formed.  At  times  the  more  resistant  parts  are  so  bound 
together  that  they  remain  in  their  original  position,  forming  a 
porous  mass,  in  the  cavities  of  which  mineral  matter  is  later  de- 
posited. 

Dynamic  disturbances  produce  cavities  of  variable  extent  in 

1  See  under  Mercury. 

2  See  under  Antimony. 

3  See  under  Gold-silver. 


456  ECONOMIC  GEOLOGY 

many  different  rocks.  These  range  from  microscopic  cracks,  like 
the  rift  planes  of  granite,  to  enormous  faults  of  great  depth  and 
linear  extent,  and  include  the  joint  planes  so  common  in  the  rocks 
of  almost  all  regions.  Fault  fissures  form  one  of  the  most  important 
types  of  passageways  for  ore-bearing  solutions.  They  are  often 
irregular,  branching,  and  partly  filled  by  fault  breccia,  caused  by 
the  breaking  of  the  rock  during  the  movement  along  the  fault 
plane.  A  third  important  group  of  cavities  in  the  rocks  are  those 
resulting  from  shrinkage  of  the  mass,  which  may  be  due  to 
(1)  shrinkage  during  cooling,  as  in  igneous  rocks;  (2)  shrinkage 
during  certain  forms  of  replacement.  For  example,  the  change  of 
calcite  to  dolomite  may  be  accompanied  by  a  shrinkage  of  the 
mass,  which  renders  the  dolomite  more  porous  than  the  original 
rock ;  and  in  the  alteration  of  siderite  to  limonite  there  is  a  shrink- 
age of  fully  20  per  cent  (139).  A  fourth  type  of  channelway  for 
the  passage  of  underground  water  is  the  contact  plane  between 
two  quite  different  kinds  of  rock,  one  of  them  fairly  dense  and 
impervious.  Gas  cavities  of  lavas  and  the  pore  spaces  of  pyro- 
clastic  rocks  may  also  serve  as  openings  for  ore  deposition. 

Deposition  of  Ore  in  Open  Cavities.  —  Open  cavities  may,  ac- 
cording to  general  belief,  exist  to  a  depth  of  many  thousands  of 
feet  below  the  surface.  If  rock  pressure  alone  were  active,  they 
could  not  theoretically  exist  below  the  zone  of  fracture,  but  it 
seems  probable  that  hydrostatic  pressure  due  to  gravity  may  to 
some  extent  counteract  rock  pressure. 

There  is  evidence  to  show  that  some  large  cavities  must  have 
existed  at  great  depths,  and  here  it  is  supposed  that  the  force  of 
crystallization  has  been  sufficient  to  spread  the  walls  apart.  Becker 
and  Day  have  demonstrated  the  actual  existence  of  such  a  force,1 
but  Lindgren  points  out  that  it  seems  scarcely  possible  to  attribute 
such  power  to  it  as  would  be  necessary  to  open  deep-seated  crev- 
vices  sufficiently  to  form  room  for  the  crystals,  and  moreover  that  it 
would  "  seem  impossible  that  under  these  conditions  comb  struc- 
ture and  coarsely,  even-grained  quartz  could  be  produced/' 
Graton  2  suggests  the  crevices  formed  below  the  zone  of  fracture 
have  been  opened  by  the  pressure  of  solutions  forced  out  of  the 
cooling  magma. 

Precipitation  of  Metals  from  Solution. — In  some  cases  the 
metalliferous  and  other  minerals  found  in  ore  deposits  have  no 

1  Proc.  Wash.  Acad.  Sci.,  VII:   283. 
8  U.  S.  Geol.  Surv.,  Bulletin  293. 


ORE   DEPOSITS  457 

doubt  been  taken  into  solution  by  surface  waters,  and  precipitated 
at  no  great  depths;  but  in  the  majority  of  instances  the  metals 
were  taken  into  solntion  at  some  point  considerably  below  the 
point  of  precipitation,  where  heat  and  pressure  were  evidently 
high.  The  ascent  then  of  these  solutions  toward  the  surface 
where  temperature  and  pressure  were  low,  would  reduce  the 
solvent  capacity  of  the  liquid  and  cause  deposition. 

As  has  been  pointed  out  by  Lindgren  (83)  the  physical  con- 
ditions during  deposition,  especially  temperature  and  pressure, 
are  of  great  importance  in  determining  the  mineral  association 
in  ores  formed  by  deposition  from  solution. 

Certain  minerals,  for  example,  are  very  stable  under  high 
pressure  and  temperature,  and  could  not  therefore  exist  under 
conditions  prevailing  near  the  surface.  That  is  to  say,  that 
the  different  minerals  have  their  "  critical  level/'  above  or 
below  which  they  cannot  form  or  exist.  Other  minerals  are 
termed  "  persistent  minerals/7  because  they  have  a  large  interval 
of  existence.1 

The  conditions  under  which  different  ore  minerals,  as  well  as 
some  others,  may  exist  are  given  in  the  following  table  (pp.  458- 
461)  compiled  by  Emmons.2 

The  deposition  of  the  metals  may  have  been  due,  however,  to 
other  causes,  such  as  the  mingling  of  waters,  resulting  in  chemical 
reactions,  contact  of  the  solution  with  reducing  agents  such  as  car- 
bon, ferrous  sulphate,  or  hydrogen  sulphide;  or  where  the  pre- 
cipitation occurs  near  the  surface,  by  oxidation. 

Other  conditions  may,  however,  operate  to  cause  precipitation, 
for,  as  shown  by  Sullivan  (86),  the  natural  silicates  have  the 
power  of  precipitating  metals  from  solution  of  salts,  "  while  at  the 
same  time  the  bases  of  the  silicates  are  dissolved  in  quantities 
nearly  equivalent  to  the  precipitated  metals."  The  bases  which 
most  commonly  replace  metals  in  such  a  process  are  potassium, 
sodium,  magnesium,  and  calcium,  and  the  metals  are  precipitated 
as  hydroxides  or  basic  salts.  Cupric  sulphide,  for  example,  is 
precipitated  as  a  basic  cupric  sulphate  similar  to  brochantite  or 
langite. 

The  same  investigator  (87)  has  also  found  that  when  a  solution 
of  ferric  sulphate  is  passed  through  a  Pasteur  filter,  18  per  cent  of 
the  iron  is  held  in  the  tube.  Repeated  passage  of  the  same  solu- 


1  A.  Grubenmann,  Die  Kristallinen  Schiefer,  Berlin,  1904,  p.  55. 
aEcon.  Geol.,  III:   611,  1908. 


458 


ECONOMIC   GEOLOGY 


MINERALS. 

06 

M 

• 

g 

Z 
O 

1 

M  PEGMATITE  VEINS 

M  CONTACT-METAMORPHIC 
DEPOSITS 

4».  DEPOSITS  OF  DEEP  VEIN 
ZONE 

DEPOSITS  OF  MODERATE 
o<  AND  SHALLOW  DEPTH. 
IGNEOUS  ROCKS  NEAR  BY 

DEPOSITS  OF  MODERATE 
as  AND  SHALLOW  DEPTH.  No 
IGNEOUS  ROCKS  NEAR  BY 

SEC'Y  MINERALS  IN  ZONES 
M  OF  OXIDE  AND  SULPHIDE 
ENRICHMENT 

QQ  PRODUCTS  OF  DYNAMO  RE- 
GIONAL METAMORPHISM 

Acmite       
Actinolite        

+ 
+  ? 

+ 

+ 

+? 
4 

Adularia          ... 

? 

4 

4 

Aegerite     
Alum     

+ 

4 

4 

Alunite      
Albite   
Allanite 

+ 

+ 
-j- 

+ 
4. 

+ 

+ 

? 

+ 

+ 
4 

Amalgam        

4 

Amphiboles    .                 ... 

4 

4 

4- 

4 

4. 

4 

4 

Andalusite      

IT 

4 

-f 

4- 

4? 

? 

-j- 

4? 

4 

Anglesite   
Anhydrite       
Ankerite    

+ 

+ 
4 

4 

+ 
4 

+ 
4 

+ 
4 

Anorthite 

4 

4 

+ 

4 

.  j_ 

Antimony       

4 

4 

-j- 

4 

4 

4 

+ 

+" 

4. 

Aquamarine        

4 

4- 

Arfvedsonite  
Argentine  
Aragonite       

+ 

+ 

+  ? 

+ 

4 

Arsenic 

4 

Arsenopyrite       
Atacamite      

+ 

+ 

+ 

+ 

? 

4 

4. 

+9 

+ 

4 

Aurichalcite  
Azurite       
Barite 

4 

+ 
4 

+ 
+ 
4? 

Bauxite      
Beryl     

+ 

+ 

+ 

+ 
4 

+? 

4 

4? 

4 

Biotite       

+? 

+ 
4 

+ 
4 

+ 
4 

4 

4 

4 

+ 

Bort                  

4 

? 

Bromyrite      

4? 

4? 

+ 

Calamine              .                 . 

4 

4 

4 

4 

Calcite       .           

+? 

+? 

4 

4 

4 

4 

4 

4 

Caledonite      
Calomel     

+? 

+ 
4 

4 

4 

4 

4 

4 

Celestite    
Cerussite        
Cerargyrite     
Chalcanthite 

+ 
+ 

+ 
+ 

4 

+ 

+ 
4 

Chalcedony    
Chalcocite            

4 

+ 
? 

+ 
4 

+ 
4 

Chalcopyrite       
Chert    
Chlorite     

+ 
4 

+ 
+? 

+ 

+? 
4 

+ 
+? 

+ 
+? 

+ 
+ 

+ 

+ 

+ 

+ 

Chrysocolla    

4 

4 

4 

4 

? 

Cobaltite   

4 

ORE   DEPOSITS 


459 


MINERALS. 

•-*  IGNEOUS  ROCKS. 

w  PEGMATITE  VEINS 

M  CONTACT-METAMORPHIC 
DEPOSITS 

^  DEPOSITS  OF  DEEP  VEIN 
ZONE 

DEPOSITS  OF  MODERATE 
en  AND  SHALLOW  DEPTH. 
IGNEOUS  ROCKS  NEAR  BY 

DEPOSITS  OF  MODERATE 
05  AND  SHALLOW  DEPTH.  Wo 
IGNEOUS  ROCKS  NEARBY 

SEC'Y  MINERALS  IN  ZONES 
M  OF  OXIDE  AND  SULPHIDE 
ENRICHMENT 

jhj 

«! 

§5 

5  « 

i 

oS 

^ 
p 

i° 
£ 

8 

+ 

t 

+? 

+ 
+ 
+? 

+ 
+ 
? 
+ 

+ 
+? 

+ 

+ 

+ 

+? 
•    +? 

+ 
+ 

+ 

? 

Copper 

+ 

+ 

? 

+ 
+ 
+ 

+ 
+ 
+? 

++ 

+ 
Weat 
Forme 

+ 

+ 

+ 

+ 

1, 

+? 
+ 

+ 
+ 

-f 
+ 

+ 

+ 
+ 

+ 
+ 

+ 

+  ? 

hering 
d  with 

+ 
+ 

+ 
+ 

+ 
+? 

+ 
+ 

+ 
+ 

+ 

+ 

+ 

? 

+ 
? 

+? 

+ 
+ 

+ 
+ 

+ 
+ 
+ 
+ 
produc 
sedime 
+? 

+ 

| 

+ 
+? 

+ 

+ 
+ 

+? 
+ 

4- 

+ 
+ 

+ 
+ 

+ 
+ 
+ 
t. 

nts 

+ 

+ 

+ 

+ 

+ 
+ 

+ 
+ 

+ 

+ 

+  ? 

+ 

+ 
+ 

+ 

+ 
? 
? 

t! 

+ 
+? 

? 

+ 

+? 

+ 
+ 

+ 

+? 
+ 

+ 
+ 
+ 

+ 

+? 

+ 

+ 
+ 

+? 

+ 
+ 
+ 
? 

+? 

+ 

+ 
+ 

+ 
+? 

+ 

+ 

+ 

+ 
+? 

+ 

+ 
+ 

+ 

4- 

+? 
+ 
+ 
+ 
+ 

+ 
+ 
+ 

Corundum      

Cordierite       

Covellite    
Cryolite     

Cuprite      

Cyanite      
Diallage     

Diopside    

Dolomite  

Eleolite      . 

Emerald    

Enargite    

Epidote     

Fayalite     ....... 
Fluorite     

Forsterite 

Franklinite     

Gahnite     

Garnet       

Gibbsite"7 

Glauconite      
Glaucophane       
Gold  (native)      
Goslarite   

Greenockite 

Graphite    

Gypsum          .     .     .     . 

Hauynite 
Hematite  ... 
Hornblende    . 
Humite  group 
Hydrozincite 
Ilmenite    . 
Iron  (native) 
Jadeite    .   .     . 

Kaolinite  
Lead  (native) 

X,eadhillite      

Lepidolite       

Xiimonite   

Malachite       

Marcasite       

"Melaconite     

Melilite 

Mercury    

Millerite 

Molybdenite       
Molybdite      

Nepheline       

460 


ECONOMIC   GEOLOGY 


MINERALS. 

1-1  IGNEOUS  ROCKS 

10  PEGMATITE  VEINS 

M  CONTACT-METAMORPHIC 
DEPOSITS 

DEPOSITS  OF  DEEP  VEIN 
ZONE 

DEPOSITS  OF  MODERATE 
oi  AND  SHALLOW  DEPTH. 
IGNEOUS  ROCKS  NEARBY 

DEPOSITS  OF  MODERATE 
05  AND  SHALLOW  DEPTH.  No 
IGNEOUS  ROCKS  NEAR  BY 

SEC'Y  MINERALS  IN  ZONES 
•o  OF  OXIDE  AND  SULPHIDE 
ENRICHMENT 

PRODUCTS  OF  DYNAMO  RE- 
GIONAL METAMORPHISM 

f 

4- 

4 

? 

Noselite     
Octahedrite 

+ 

4 

4 

4. 

? 

4 

Opal 

+? 

4 

4 

4 

4 

Orthoclase      

+ 

+ 

+ 

+ 

+ 
4 

4. 

? 

4. 

4 

Petzite                   

4 

Picotite 

4 

4 

4 

4? 

? 

+? 

+? 

4 

4 

4 

4 

4 

Pyrargyrite    
Pyrite                          .... 

+ 

4 

4 

4 

+ 
4 

4 

4 
4 

4- 

4 

4 

4 

4 

Weat 

hering. 

Pyroxenes       

+ 

4- 

4 

4 

4 

4- 

4 

4 

4 

+ 

4. 

4 

4 

4 

4 

4 

4 

Realgar      
Rhodochrosite    
Rhodonite      

+ 

+ 
4 

4 

4 
+ 
4 

+ 

? 

+ 

Riebeckite      
Ruby 

4- 

+? 

Rutile   

+ 
J- 

+ 

4 

+ 

4? 

+ 

+ 

? 

+ 

4 

4 

+ 

Scheelite    
Selenite      

+ 

+? 

+ 

4 

4 

Sericite 

4 

4 

4 

+ 

Siderite      

4 

4 

+ 

+ 

+ 

+ 

+ 
4 

Silver  (native)     
Smithsonite    ...... 
Sodalite     

+? 

+ 

+ 

+ 

4 

? 

4 

+ 
4 

4 

Spinel   

4 
-j- 

+ 
4- 

+ 

+ 

+ 

4 

4- 

Steatite,  talc       

Surfa 

ce   alte 

ration 

4 

4- 

Stibnite      

? 

4 

4- 

Stilbite       
Stromeyerite       
Sulphur      

+? 

? 

4 

+ 
4 

+ 

Sylvanite             .          ... 

+? 

? 

+ 

Talc      
Tellurides       .     .           ... 
Tennantite     .     .           ... 
Tenorite 

Surfa 

ce  wea 

thering 
? 

+ 

+ 

+ 

+? 

Tetradymite        .           ... 
Tetrahedrite        .           ... 
Tin  (native) 

+ 
+ 

? 

+ 
4 

4 

Titanite     

4 

+ 

4 

_j_ 

Topaz              

-j- 

4. 

4 

4 

4 

ORE   DEPOSITS 


461 


H 

% 

M       '    ® 

W  ^  pj 

s  ^ 

w  S 

O 

S    W    PH 

^   K  ^ 

o  W 

•—  ^ 

Ea 

^ 

^    V   "^ 

PS  H  "^ 

N  ^ 

o  w 

MINERALS. 

00 

H 

§ 

gg 
g 
3 

METAMORPI 

'18 

O-i 

Q 

h 

o 

OF  MODEH 
ALLOW  DE] 

8  ROCKS  Ni 

OF  MODE 

ALLOW  DEP 

s  ROCKS  Ni 

NERAL8  IN 
DE  AND  SUI 
MENT 

i  OF  DYNAM 
METAMORP 

NEOUS  '. 

<! 

s 

i 

DNTACT- 

DEPOSI 

EP08IT8 

ZONE 

E  POSITS 

AND  SH 
IGNEOU 

EPO8IT8 
ANDSH. 

IGNEOU 

21  1 

IODUCT8 
GIONAL 

O 

OH 

U 

Q 

Q 

Q 

& 

An 

1 

2 

0 

4 

5 

6 

7 

8 

Tourmaline 

+ 

+ 

+ 

+ 

Tremolite 

-[- 

4- 

_|_ 

Tridymite 
Turgite  &  amorphous  hematite 
Turquoise 
Uralite       . 

+ 

+7 

+T 

+ 

+ 

I? 

Valencianite 

? 

-|- 

Vesuvianite 

_[- 

_|_ 

Willemite 

_j_? 

~f~? 

_j_ 

Witherite 

? 

? 

-(- 

Wolframite 

-j- 

-(- 

Wollastonite 

-f 

_j- 

Wurtzite    . 

-(- 

-(-? 

Xenotime 

-)- 

_[- 

Yttrialite  . 

-(- 

Zeolites      .                           .     . 

-)- 

Zincblcnci.6 

7 

j_ 

_L 

4- 

J_ 

-f 

j_7 

7 

Zincite        

_j_? 

f 

+ 

Zircon                    

-f 

Zoisitc 

1 

4- 

tion  caused  the  retention  of  additional  quantities  of  the  same 
metal.  The  explanation  advanced  is  that  hydrolysis  has  pro- 
duced a  colloid  form  of  the  iron  oxide,  which  is  caught  in  the 
pores  of  the  porcelain.  The  experiment  is  highly  suggestive  and 
indicates  that  metalliferous  solutions  in  passing  through  porous 
rocks  may  be  robbed  of  some  of  their  metallic  contents  by  a 
similar  process. 

And  this  brings  up  the  question  of  whether  the  minerals  are 
precipitated  in  ore  deposits  as  crystals  or  colloids.  In  the  case 
of  deposits  forjned  below  the  surface  and  above  surface  temper- 
atures, crystalline  precipitates  probably  prevail;  but  at  the  sur- 
face many  metallic  and  non-metallic  compounds  are  no  doubt 
thrown  down  in  colloidal  form,  even  though  they  may  later 
change  to  the  crystalline  condition  (79,  82). 

Some  fifty  years  ago  not  a  few  geologists,  prominent  among 
them  De  la  Beche,  advocated  the  theory  of  ore  precipitation  by 
galvanic  action  (72,  77,  91),  and  a  number  of  experiments  were 
made  attempting  to  prove  the  existence  of  such  action;  now  little 
weight  is  attached  to  this  theory. 


462 


ECONOMIC  GEOLOGY 


Replacement,  or  Metasomatism  (99-105). — It  is  a  well-known 
fact  that  under  favorable  conditions  mineral-bearing  solutions  may 
attack  the  minerals  of  the  rocks  which  they  penetrate,  dissolving 


FIG.  138.  —  Vein  breccia  from  Freiberg,  Germany. 

The  specimen  shows  fragments  of  altered  schist  (5),  which  are  in  some 
cases  surrounded,  and  in  others  more  or  less  completely  replaced  by  sphal- 
erite (Z),  and  cemented  by  quartz  (Q).  Scattered  grains  of  pyrite  (P)  are  also 
present.  (Specimen  in  Cornell  collection.) 


them  wholly  or  in  part,  and  depositing  some  of  the  original  burden 
in  place  of  the  material  removed.  This  replacement,  termed 
"  metasomatism/'  is  an  important  factor  in  the  formation  of  many 
ore  deposits,  and  may  involve  a  total  or  partial  loss  of  certain 
constituents  of  the  rock  attacked  and  a  gain  of  others,  even  to 
the  extent  of  introduction  of  entirely  new  compounds  and 
elements. 


ORE   DEPOSITS 


463 


While  some  (100)  believe  that  replacement  may  be  accom- 
panied by  a  volume  change,  others  (102)  assert  that  it  proceeds 
independent  of  molecular  weight, 
molecular  volume,  and  specific 
gravity. 

The  replacing  solutions  gain 
entrance  to  the  rock  mass,  along 
fractures  of  different  sorts,  and 
penetrate  the  rock  first  along  the 
smallest  cracks,  and  then  work 
their  way  into  the  individual  min- 
eral grains  along  their  cleavage 
planes  until  they  finally  permeate 

the  entire  mass  (Figs.  139,  140,  FlG  139._phot0.micrograph  of 
and  142).  The  reactions  between 
the  dissolved  mineral,  and  the 
original  rock  probably  take  place 
in  films  of  the  solution  coating  the 
grains. 

Metasomatic  processes  show  great  variety,  and  are  not  confined 


section  of  quartz  conglomerate, 
showing  replacement  of  quartz 
(white),  by  pyrite  (black),  X25 
diam.  (After  Smyth,  Amer.  Jour. 
Sci.,  XIX,  1905.) 


FIG.  140.  —  Pyrite   replacing   hornblende,    Mineral,  Louisa   County,  Va.     X35. 
Black,  pyrite;   gray,  hornblende;   white,  quartz. 

to  one  kind  of  rock  or  mineral.     In  its  simplest  form  the  result  of 
metasomatism  may  often  be  seen  in  fossiliferous  rocks,  where 


464 


ECONOMIC  GEOLOGY 


organic  remains  have  been  replaced  by  common  mineral  com- 
pounds, as  in  the  replacement  of  the  lime  carbonate  of  corals  by 
quartz,  or  the  replacement  of  molluscan  shells  by  pyrite.  From 
such  simple  conditions  there  is  every  gradation  to  the  com- 
plete replacement  of  extensive  areas  of  rock  by  ore,  or  to  the 
extensive  operation  of  metasomatism  along  the  walls  of  fissure 
veins. 

The  complexity  of  metasomatic  processes  referred  to  above 
may  be  due  to  variations  in  temperature,  character  of  rock,  and 

nature  of  solution.  Metasom- 
atism may  take  place  through  a 
wide  range  of  temperature,  but 
heat  greatly  aids  the  process,  and 
the  replacing  solutions  while  usu- 
ally liquid,  may  also  be  gaseous. 
Of  the  many  different  rocks  af- 
fected, limestones  are  most  favor- 
able to  replacements,  while  those 
high  in  alumina  are  least  easily 
attacked. 

The  original  structure  and  even 
the  texture  of  the  rock  may  be 
preserved,  although  its  mineral 
composition  is  completelyaltered, 
illustrations  of  the  former  being 
sometimes  seen  in  silicified  lime- 
stones, or  of  the  latter  in  replaced 
porphyritic  rocks,  in  which  the 
outlines  of  the  phenocrysts  are 
still  preserved/ 

The  replacing  mineral  is  referred  to  as  the  metasome,  while 
if  it  shows  crystal  outlines  it  is  called  a  metacryst,  and  some  min- 
erals in  replacement  show  a  greater  tendency  to  develop  crystals 
than  others. 

Replacement  at  high,  temperatures  is  usually  indicated  by 
complete  recrystallization,  the  development  of  silicate  minerals 
with  little  or  no  water,  and  coarse  texture.  That  performed  at 
lower  temperatures  commonly  results  in  a  much  finer-textured 
mass. 

To  definitely  decide  whether  replacement  has  occurred,  both 
field  and  laboratory  study  is  often  necessary.  In  hand  specimens 


FIG.  141.  —  Replacement  vein  in 
syenite  rock,  War  Eagle  Mine, 
Rossland,  B.C.  (a)  granular  ortho- 
clase  with  a  little  sericite;  (6)  sec- 
ondary biotite;  (q)  secondary 
quartz;  (c)  chlorite;  black,  second- 
ary pyrrhotite.  (After  Lindgren, 
Amer.  Inst.  Min.  Engrs.,  Trans. 
XXX.) 


ORE  DEPOSITS  465 

it  is  not  always  possible,  without  examination  of  a  thin  section 
under  the  microscope,  to  decide  whether  the  minerals  present  are 
due  to  replacement  or  to  simple  interstitial  filling. 

Certain  criteria  representing  both  field  and  laboratory  features 
have  been  suggested  (100),  although  all  are  rarely  applicable  to  a 
single  deposit.  These  are:  (1)  Presence  of  complete  crystals  in 
foreign  rock  masses;  (2)  Preservation  of  rock  structures;  (3) 
Intersection  of  rock  structures  by  replacing  mass;  (4)  Absence 
of  crustification;  (5)  Presence  of  unsupported  nuclei;  (6)  Rela- 


FIG.  142.  FIG.  143. 

FIGS.  142  and  143.  —  Photo-micrographs  of  thin  sections  of  ore  from  Austinville, 
Va.,  mines.  X  20  diam.  crossed  nicols.  Shows  crystalline  granular  dolomitic 
limestone,  and  the  filling  of  fine  cracks  accompanied  by  replacement  of  lime- 
stone grains  along  crystallographic  directions  by  the  sulphides.  Very  dark 
irregular  areas  in  center  represent  sulphides.  Reentrant  angles  along  mar- 
gins of  the  sulphides  and  the  spider-like  arrangement  of  the  sulphide  areas  as 
a  whole  are  well  shown.  (After  Watson,  Va.  Geol.  Sure.,  Bull.  I.) 

tion  of  replacement  to  fissures  and  other  cavities;  and  (7)  Form 
of  deposit. 

As  mentioned  before,  metasomatic  processes  show  endless 
variety.  Non-metallic  minerals  may  replace  each  other  as 
quartz  replacing  calcite,  or  metallics  may  replace  nonmetallics, 
as  galena  in  limestone  or  pyrite  in  hornblende  (Fig.  140);  and 
lastly  one  sulphide  may  be  replaced  by  another,  as  pyrite  by 
chalcocite  (Plate  XLII),  or  sphalerite  by  chalcocite. 

Although  the  process  of  metasomatism  was  recognized  by 
Charpentier  as  early  as  1778,  it  was  generally  disregarded,  and 
not  widely  accepted  or  recognized  until  many  years  later,  and 
geologists  continued  to  assume  that  ores  precipitated  from  solu- 
tion were  deposited  in  cavities.  Replacement  was,  however, 


466  ECONOMIC  GEOLOGY 

finally  recognized  in  the  United  States,  being  applied  by  Pum- 
pelly  to  the  Lake  Superior  copper  deposits  in  1873;  by  Emmons  to 
Leadville  in  1886,  and  by  Irving  and  Van  Hise  to  the  Gogebic 
Range  in  1887  to  1888. 

Ore  deposits  of  great  size,  as  those  of  Leadville,  Colorado, 
or  Bisbee,  Arizona,  may  be  formed  by  replacement,  and  a  fre- 
quent expression  of  it  is  seen  in  the  alteration  of  the  wall  rocks 
of  many  fissure  veins.  (See  Hydrothermal  alteration,  p.  486.) 

Forms  of  Ore  Bodies  (163) .  —  Ore  bodies  vary  greatly  in  their 
form,  and  this  character  has  at  times  been  used  as  a  basis  of  classi- 
fication by  some  writers:  but  the  more  modern  tendency  is  to  use 
genetic  characters  instead,  making  shape  of  secondary  importance 
in  the  grouping.  Certain  forms  of  ore  bodies  are  so  numerous  as  to 
deserve  special  mention. 

Fissure  Veins  (2,  21,  125,  127,  128,  131,  133,  135,  138,  163).  — A 
fissure  vein  may  be  defined  (103)  as  a  tabular  mineral  mass 
occupying  or  closely  associated  with  a  fracture  or  set  of  fractures 
in  the  inclosing  rock,  and  formed  either  by  filling  of  the  fissures 
as  well  as  pores  in  the  wall  rock,  or  by  replacement  of  the  latter 
(metasomatism).  When  the  vein  is  simply  the  result  of  fissure 
filling,  the  ore  and  gangue  minerals  are  often  deposited  in  successive 
layers  on  the  walls  of  the  fissure  (Rico,  Colorado),  the  width 
of  the  vein  depending  on  the  width  of  the  fissure  and  the  boundaries 
of  the  ore  mass  being  sharp.  In  most  cases,  however,  the  ore- 
bearing  solutions  have  entered  the  wall  rock  and  either  filled  its 
pores  or  replaced  it  to  some  extent,  thus  giving  the  vein  an 
indefinite  boundary.  Therefore  the  width  of  the  fissures  does 
not  necessarily  stand  in  any  direct  relation  to  the  width  of  the 
vein  (138)  (Butte,  Montana).  The  term  vein  material  is  best 
used  to  apply  to  the  aggregate  of  materials  which  make  up  the 
ore  body.  Vein  stone,  though  sometimes  used,  is  less  desirable 
(Emmons) . 

Veins  formed  by  the  simple  filling  of  a  fissure  often  show  a 
banded  structure  of  varying  regularity  termed  crustification  1  by 
Posepny  (Plate  XXXIX,  Fig.  1  and  Fig.  144),  which  may  some- 
times be  brecciated  by  later  movements  along  the  fissure.  Sec- 
ondary bands  may  be  formed  after  reopening  of  the  fissures  (Fig. 
144) ,  and  such  a  movement  may  cause  brecciation  of  the  vein  ma- 
terial. There  are  many  filled  fissure  veins  in  which  banding  is 

1  The  replacement  of  certain  layers  only  in  a  bed  of  stratified  rock  may  also 
produce  a  banded  structure. 


PLATE  XL 


FIG.  1. — Banded  vein  from  Clausthal,  Germany.  Sphalerite,  S;  Quartz,  Q; 
Argillite  wall  rock,  W,  fragments  of  which  have  been  separated  by  quartz 
crystallizing  in  the  cracks. 


FIG.  2. — Banded  vein,  same  locality.     Sphalerite,  S;    Galena,  G;    Chalcopyrite, 
C  (black);  Calcite,  C  (white);  streak  of  later  quartz,  Q. 

(467) 


468 


ECONOMIC   GEOLOGY 


absent,  the  ore  minerals  and  gangue  being  intermixed,  but  so  re- 
lated as  to  indicate  probably  simultaneous  deposition  of  the  two. 

Later  movement  along 
the  vein  wall  may 
sometimes  form  a 
layer  of  soft,  clayey 
material,  known  as 
gouge  or  selvage,  be- 
tween the  vein  and 
the  country  rock,  but 
where  the  vein  filling 
adheres  closely  to  the 
country  rock  it  is  said 
to  be  frozen  to  the  walls. 
Where  the  fissure  has 
not  been  completely 
filled,  thus  leaving  a 
central  space  into 
which  the  crystals  of 
gangue  project,  a 
comb  structure  is  form- 
ed. The  bands  in  a 
filled  fissure  may  con- 
sist of  gangue  and 
ore  alternating,  or  of 


FIG.  144.  —  Section  of  vein  in  Enterprise  mine,  Rico, 
Colo.  The  right  side  shows  later  banding  due  to 
reopening  of  the  fissure.  (After  Ransome,  U.  S. 
Geol.  Surv.,  22d  Ann.  Kept.,  //.) 


different  ores.  Among  the  commonest  ore  minerals  seen  in  these 
fissure  veins  are  pyrite,  chalcopyrite,  galena,  blende,  and  sulphides 
of  silver.  Some  regions  afford  especially  fine  examples  of  banded 
veins,  notably  those  of  Grass  Valley,  California,  and  Rico,  Colorado. 
Abroad  the  mines  of  Freiberg,  Saxony,  and  Clausthal,  Prussia,  also 
often  yield  magnificent  specimens.  Even  in  a  single  vein  the  ore 
may  follow  certain  streaks  which  are  termed  shoots  (q.v.)  or  again  it 
may  be  restricted  to  pockets  of  great  richness,  which  are  known  as 
bonanzas. 

In  some  veins  the  friction  breccia  or  dragged  in  fragments  of  the 
country  rock  form  a  considerable  portion  of  the  vein  filling,  and  the 
ore  has  been  deposited  in  layers  around  these  fragments. 

Fissure  veins  in  which  metasomatic  action  has  predominated 
show  great  irregularity  of  width  and  an  absence  of  well-defined 
boundaries ;  they  also  lack  as  a  rule  the  symmetrical  banding  and 
the  breccias  cemented  by  vein  material.  There  are  all  gradations 


FIG.  1. — Vein  specimen  from  Przibram,  Bohemia;  Galena,  G;  Stibnite  and 
quartz,  A;  Galena  and  quartz,  M;  Dolomite,  C;  Quartz,  Q;  Fragments  of 
graywacke  wall  rock,  W. 


FIG.  2. — Veinlets  of  tin  ore  in  granite,  Altenberg,  Saxony. 

(469) 


470 


ECONOMIC  GEOLOGY 


between  these  two  types  of  fissure  veins ;   and  even  in  a  single  vein 
simple  filling  may  occur  in  one  part  and  replacement  in  another. 

Veins  often  split  or  intersect,  and  at  the  point  of  intersection  or 
splitting  the  ore  is  apt  to  be  richer.     There  are  other  reasons  for 

variations  in  richness,  among  the 
most  important  being  the  char- 
acter of  the  wall  rocks,  some 
kinds  being  more  easily  replace- 
able or  more  porous  than  others. 
Their  physical  character  will 
moreover  exercise  considerable 
influence  on  the  shape  and  size 


FIG.  145.— Section  showing  change  in  of  the  fissure.  Tough  rocks  like 
character  of  vein  passing  from  gneiss  gneiss,  for  example,  give  a  clean- 
(</)  to  quartz  porphyry  (p).  (After  ,  fissnrp  but  in  brittle  rock 

r\      T         T     j  7  I-T      7  L*  L1L      llOoU.lt/*      U  U.  LI     111      LJ1 1  L  Llvj     IvJL/iv 

Beck,    Lehre   von   der   Erzlagerstatten :  '  t 

135.)  the  fissure  is  apt  to  split  fre- 

quently,   and   therefore  a  vein 

may  be  workable  in  one  kind  of  rock,  but  becomes  worthless  when 
passing  to  another,  since  the  profuse  branching  interferes  with  eco- 
nomical mining  (Fig.  145).  A  dike  may  also  cause  local  irregu- 
larities, and  in  a  given  region  the  fissures  not  uncommonly  show  great 
variation  in  their  direction.  Thus  at  Butte,  Montana  (q.v.),  east- 
west  veins  predominate, 
while  in  the  Silverton  dis- 
trict of  Colorado  they  cut 
the  rocks  in  all  directions, 
but  the  majority  show  a 
north  of  east  trend.  In  the 
Monte  Cristo,  Washington, 
district  the  veins  with  w 
northeast  trend  are  pre- 
dominant (Fig.  146). 

Fissure  veins  vary  con- 
siderably in  their  width, 
swelling  at  some  points  and 
pinching  or  narrowing  at 
others.  They  also  at  times  _ 

FIG.    146. —  Tabulation  of  strikes  of  principal 

show    lateral     enrichment        veins   in    Monte   Cristo,  Wash.,   district. 

(Ouray,  Colorado)  ;   for  in-  (After  Spurr,   U.  S.   Geol.   Surv.,   22d  Ann. 

stance,  where  the  ore  cuts        Rept''  n'^ 

through    stratified    beds,   into    which    the    ore-bearing    solutions 


ORE  DEPOSITS 


471 


have  spread  out  laterally  along  the  p.anes  of  stratification  or 
other  planes.  It  has  been  noticed  in  some  veins,  especially  those 
formed  by  replacement,  that  the  filling  varies  with  the  wall  rock, 
at  times  changing  suddenly;  but  where  the  vein  is  formed  wholly 
by  the  filling  of  an  open  fissure,  the  rock  exerts  no  influence  on 
the  character  of  the  ore  (138).  If  the  vein  is  inclined,  the  lower 
wall  is  spoken  of  as  the  foot  wall  and  the  upper  one  as  the  hanging 
wall. 

A  horse  is  a  mass  of  rock  broken  off  from  the  vein  wall,  and 
held  between  the  walls  of  the  fissure.  It  is  often  surrounded  by 
ore,  and  may  itself  sometimes  be  mineralized  to  a  varying 
degree. 

Parallel  fissures  are  not  uncommon,  but  the  several  veins  do  not 
necessarily  show  an  equal  degree  of  richness.  Where  the  vein  is  of 


FIG.  147.  —  Linked  veins.     (After  Ordonez.) 

composite  character, — that  is,  consisting  of  closely  spaced  parallel 
fissures  accompanied  sometimes  by  a  mineralization  of  the  inter- 
vening rock,  —  it  is  termed  a  lode. 

The  term  vein  systems  is  suggested  for  a  larger  assemblage  of  vein 
fissures,  which  may  include  several  lodes. 

Subordinate  fractures,  such  as  little  veins,  that  cross  the  material 
included  within  the  vein  walls,  are  called  veinlets  or  stringers. 

The  top  of  the  vein  is  called  the  apex,  and  is  occasionally  trace- 
able for  a  long  distance.  It  does  not  necessarily  outcrop  at  the 
surface. 

Linked  veins  represent  a  type  in  which  the  parallel  fissures  are 
connected  by  diagonal  ones  (Fig.  147),  giving  a  series  resembling 
the  links  of  a  chain. 


472  ECONOMIC   GEOLOGY 

Gash  veins  are  a  special  type  of  fissure  vein  of  limited  extent. 
Some  are  formed  by  the  enlargement  of  joint  planes  and  some- 
times bedding  planes. — They  are  characteristic  of  the  upper 

Mississippi  Valley  lead  and  zinc 
region,  but  are  usually  of  limited 
extent  and  local  importance. 

^__^_  In  ^e  simplest  form  they  are  a 

/-^  J_        x         \  vertical  fissure,  but  develop  into 

.V  .   —       — °       ^-     types  shown  in  Fig.  148.     Other 

FIG.  148.  -  Gash  vein  with  associated       Sash  veins  may  be  the  result  of 

"  flats  "    (a)  and   "  pitches  "  (6).     torsional  strain,  as  those  accom- 

Wisconsin      zinc     region.       (After       panymg    the     Catocthl    type    of 
Grant,    Wis.   Geol.   and   Nat.   Hist.  JP 

Sun.,  Bull.  IX.)  copper  ores. 

Bedded  Vein.  • —  This  term    is 

sometimes  applied  to  a  deposit  conforming  with  the  bedding. 
It  is  also  called  bedded  deposit.  Among  miners  the  term  blanket 
vein  is  commonly  applied  to  any  nearly  flat  deposit. 

Bedded  deposits,  found  parallel  with  the  stratification  of  sedi- 
mentary rocks,  and  sometimes  of  contemporaneous  origin  (Clin- 
ton iron  ore). 

Cross  veins  is  a  term  applied  to  those  which  cross  the  stratifica- 
tion. 

Lenticular  veins  are  short  lenses,  frequently  found  in  meta- 
morphic  rocks,  and  often  scattered  along  a  line,  or  lying  more 
or  less  parallel  in  a  zone. 

Filling  of  Fissure  Veins  (131).  —  The  manner  in  which  fissure  veins  have 
been  filled,  and  the  source  of  the  metals  which  they  contain,  formed  a  most 
fruitful  subject  of  discussion  among  the  earlier  geologists.  The  several 
theories  advanced  and  the  arguments  for  and  against  them  are  well  set 
forth  in  Kemp's  paper  (131),  and  it  may  simply  be  said  here  that  most 
geologists  now  believe  that  the  primary  deposition  of  ores  in  fissure-vein 
deposits  was  accomplished  by  solutions  ascending  along  the  fissures,  which 
sometimes  spread  out  into  the  wall  rocks,  to  a  variable  distance. 

Other  Forms  of  Ore  Deposits. — Chimney  is  a  term  applied  to  ore 
bodies  which  are  rudely  circular  or  elliptical  in  horizontal  cross-sec- 
tion, but  may  have  great  vertical  extent.  A  stock  is  a  somewhat 
similarly  shaped  ore  body,  but  of  greater  irregularity  of  outline. 
Fahlband  is  a  term  originally  used  by  German  miners  to  indicate 
certain  bands  of  schistose  rocks  impregnated  with  finely  divided 
sulphides,  but  not  always  rich  enough  to  work.  It  is  occasionally 
used  in  this  country.  Stockwork  is  the  term  applied  to  a  rock 


ORE   DEPOSITS 


473 


mass  broken  in  different  directions  by  short  fissures,  which  may 
be  mineralized.  Impregnation  is  a  term  indicating  the  occur- 
rence of  minerals  in  a  finely  disseminated  condition  in  rocks,  either 


FIG.    149.  —  Section   at   Bonne   Terre,  Mo.,  showing   ore   disseminated   through 

limestone. 

as  a  filling  of  open  spaces  or  as  a  replacement  of  certain  minerals. 
Disseminated  deposits  (Fig.  149)  is  regarded  as  a  better  term  by 
some.  Contact-metamorphic  deposits,  as  now  understood,  represent 
ore  bodies  formed  along  the  contact  of  a  mass  of  igneous  and 

LONGITUDINAL  SECTION 


illy 


FIG.  150. 


FIG.  151. 


FIGS.  150  and  151.  —  Sketch  showing  dimensions  of  an  ore  shoot. 

gren  and  Ransome.) 


(After  Lind- 


country  or  invaded  rock  (usually  calcareous),  the  ore  having  been 
derived  wholly  or  in  part  from  the  intrusive  mass  (Clifton,  Arizona, 
in  part).  If  the  term  contact-metamorphic  deposit  is  used  for  this 
type,  it  would  not  necessarily  conflict  with  the  term  contact 
deposit,  applied  to  any  ore  body  occurring  along  the  boundary 
between  two  formations  or  two  kinds  of  rock.  Ore  channels 
include  those  ore  bodies  formed  along  some  path  which  the  mineral 


474  ECONOMIC  GEOLOGY 

solutions  could  easily  follow,  as  the  boundary  between  two  differ- 
ent kinds  of  rock  (Mercur,  Utah). 

Shear  zones  or  sheeted  zones  represent  a  zone  of  rock  broken  by 
numerous  parallel  and  often  closely  spaced  fractures,  which  may 
be  mineralized  as  at  Cripple  Creek,  Colorado  (Fig.  262). 

Ore  shoots  (92-96) .  —  Few  ore  deposits  are  of  uniform  character 
throughout,  indeed  the  occurrence  of  pay  ore  is  apt  to  be  more 
or  less  irregular,  the  richer  material  being  often  somewhat  re- 
stricted in  its  occurrence.  These  richer  portions,  if  small,  may  be 
called  nests,  or  pockets,  but  if  large,  the  term  ore  shoot  is  commonly 
applied  to  them.  According  to  some  authors  the  ore  shoot 
includes  only  the  richer  portion  of  the  workable  ore.  (Van 
Hise.) 

Other  writers,  among  them  Emmons,  Lindgren  and  Ransome, 
employ  the  term  ore  shoot  or  pay  shoot  to  signify  the  workable 
part  of  a  lode  or  similar  deposit. 

Ore  shoots  are  commonly  of  irregular  shape,  and  usually  steep  dip, 
although  they  may  be  nearly  horizontal. 

According  to  Emmons  the  ore  shoot,  as  a  rule,  has  a  longer  axis 
that  forms  a  large  angle  with  a  horizontal  plane.  This  longer  axis 
may  be  called  the  pitch  length,1  and  the  horizontal  dimensions  along 
the  level  the  slope  length.  Ore  shoots  are  evidently  caused  by  vary- 
ing chemical  and  physical  conditions  in  different  parts  of  the  deposit, 
at  the  time  the  ore  was  formed,  thus  causing  a  more  abundant  pre- 
cipitation of  the  ore  minerals  in  certain  parts  of  the  deposit.  More 
abundant  fissuring,  or  brecciation,  in  certain  parts  of  the  rock  may 
operate  to  promote  deposition  in  those  parts  of  the  mass ;  clay  walls 
may  be  influencing  factors  in  guiding  the  ore  solutions  towards 
certain  spots ;  or  intersecting  fissures  may  permit  the  mingling  of 
reacting  solutions,  thereby  bringing  about  more  abundant  precipita- 
tion of  ore  at  these  crossing  points.  The  existence  of  fissures  in 
certain  parts  of  the  ore  body  might  produce  additional  deposition 
in  those  parts,  by  serving  as  a  guiding  channel  to  either  ascending 
or  descending  enriching  solutions. 

The  examples  cited  above  apply  especially  to  epigenetic  deposits; 
but  if  the  term  ore  shoot  is  used  in  its  broadest  sense,  one  might 
reasonably  include  ore  masses  formed  by  magmatic  segregation. 

Several  attempts  have  been  made  to  classify  ore  shoots,  all  of  them 
being  on  a  genetic  basis.  Thus  Van  Hise  2  divides  them  into  three 

1  Lindgren  and  Ransome. 

2  Amer.  Inst.  Min.  Engrs.,  Trans.  XXX:     27. 


ORE   DEPOSITS  475 

groups  as  f  ollows  :  (A)  those  explained  largely  by  structural  features; 
(B)  those  formed  by  the  influence  of  wall  rocks ;  and  (C)  those 
formed  by  secondary  concentration  by  descending  waters. 

Irving  (92)  has  classified  them  as  (1)  shoots  of  variation,  or  those 
which  vary  from  the  inclosing  material  only  in  relative  richness  of 
the  ore;  and  (2)  shoots  of  occurrence,  or  those  which  occur  in  iso- 
lated positions  with  no  other  ore  of  any  kind  about  them. 

Winchell 1  makes  a  division  into  (1)  paragenetic  shoots,  or  those 
developed  mostly  at  the  time  of  the  original  formation  of  the  ore 
deposit  inclosing  them;  and  (2)  postgenetic  shoots,  or  shoots  devel- 
oped mostly  after  the  original  formation  of  the  inclosing  ore  deposit. 

Secondary  Changes  in  Ore  Deposits  (106-122,  155-158).  —  Ore 
deposits  are  often  changed  in  their  upper  parts,  and  sometimes 
to  a  considerable  depth,  by  weathering  agents,  while  the  lower- 
lying  portions,  below  the  ground-water  level,  are  often  enriched  by 
secondary  processes. 

The  two  zones  each  show  a  somewhat  characteristic  set  of  com- 
pounds. Thus  in  the  weathered  zones  we  find  sulphates,  carbonates, 
silicates,  oxides,  chlorides,  arsenates  and  native  metals;  while  in  the 
lower  zone  the  compounds  are  sulphides,  tellurides,  arsenides,  and 
antimonides. 


^^v-.-VTv    ''       --' 


Baiter  Tunnel  Level 

Z. B.  Level 

61  Holbrook 
No.2  Level  Ca»r  and  Holbrook 


. No.3  Level  Czar  and  Holbrook 

No.4  Level  Czar  and  Holbrook 

No.5  Level  Holbrook 


FIG.  152. —  Section  through  Copper  Queen  Mine,  Bisbee,  Ariz.,  showing  variable 
depth  of  weathering.     (After  Douglas,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXIX.} 

Weathering  may  disguise  the  true  character  of  an  ore  body 
most  effectually.  For  example,  the  ore  found  in  the  outcrop  may 
be  a  gold  ore,  and  mills  are  sometimes  erected  and  operated  for  a 
period  on  such  ore,  without  any  suspicion  that  beneath  there  may 
be  great  bodies  of  copper  or  lead  sulphides.  Such  a  change  has 
been  found  at  Bingham,  Utah;  Butte,  Montana;  or  Mount 
Morgan,  Australia.  The  last  has  been  one  of  the  world's  greatest 
gold  mines,  but  is  now  producing  copper  from  its  lowest  levels. 

Geol.,  III:   425,  1908. 


476  ECONOMIC  GEOLOGY 

In  other  cases,  the  base  metals  may  all  have  been  leached  out  of  the 
upper  part  of  the  ore  body,  and  too  little  gold  remains  in  the  gossan 
to  make  it  profitable.  Butte,  Montana,  is  a  well-known  example 
of  this,  for  the  nearly  barren  outcrops  gave  little  clew  to  the  great 
sulphide  ore  bodies  lying  below,  and  which  might  never  have 
been  discovered  but  for  the  presence  of  another  system  of  closely 
associated  veins  carrying  silver. 

Weathering  or  Superficial  Alteration  (155-158).  —  Nearly  all 
minerals  are  attacked  by  the  weathering  agents,  but  the  metallic 
minerals  are  more  easily  and  more  profoundly  affected  than  the 
non-metallic  ones. 

This  weathering  process  involves  both  chemical  and  physical 
changes  similar  to  the  decay  and  disintegration  of  common  rocks, 
but  in  ore  bodies  the  great  number  of  minerals  involved,  includ- 
ing many  with  a  metallic  base,  give  rise  to  a  large  number  of  in- 
tricate chemical  reactions. 

As  a  result  of  weathering  worthless  minerals  may  be  removed, 
leaving  the  weathered  part  more  porous,  and  this  may  increase 
the  richness,  because  we  have  a  greater  quantity  of  metals  per 
ton  of  rock. 

The  character  of  the  outcrop  in  non-glaciated  areas  depends 
on  the  relative  resistance  to  weathering  of  the  ore  and  wall 
rock.  Hard  quartz  veins,  silicified  ledges  (Plate  LVIII,  Fig.  2), 
or  dense  fine-grained  garnet  rock  are  usually  more  resistant  than 
the  country  rock,  and  may  remain  standing  in  more  or  less  strong 
relief.  Pyritic  deposits  weather  more  easily  usually  than  the  wall 
rock,  and  hence  a  depression  may  be  developed. 

A  mixture  of  quartz  and  pyrite  will  yield  a  mass  of  rusty 
honeycombed  quartz,  or  a  hard  porous  limonite,  such  a  mass 
being  known  as  gossan  or  iron  hat  (French,  Chapeau  de  fer;  Ger- 
man, Eisener  Hut}.  Solid  sulphide  ore  bodies  also  are  often 
capped  by  a  gossan. 

'The  weathering  of  an  ore  body  is  a  comparatively  slow  process, 
so  that  in  glaciated  areas,  unweathered  ore  may  extend  close 
to  or  actually  up  to  the  surface,  because  since  the  retreat  of  the 
ice  the  time  has  been  too  short  to  permit  much  weathering. 

Oxidation  in  general  extends  to  the  water  level,  although 
there  may  be  a  number  of  exceptions  to  this  rule.  It  may  hence 
show  great  variation  in  depth  due  to  this  cause  alone,  but  aside 
from  this  other  factors  exert  an  influence,  such  as  topographic 
conditions,  rainfall,  nature  of  the  rock,  whether  fissured,  porous 


ORE   DEPOSITS  477 

or  dense,  kind  of  ore  minerals,  climate,  etc.  Even  in  the  same 
deposit  oxidation  may  extend  to  greater  depths  in  one  place  than 
another  (Fig.  152),  because  of  the  presence  of  fissures  which  per- 
mitted local  penetration  of  the  surface  waters. 

As  examples  of  the  maximum  depth  to  which  weathering 
may  extend  in  some  parts  of  an  ore  body  the  following  can  be 
mentioned : 

Bisbee,  Ariz.      .     .     .     .    V 1600  feet  in  places. 

Tin  tic,  Utah 2000 

Bingham,  Utah      . 1300 

Tonopah,  Nev.     ••'.     .     .     v 1200 

Ducktown,  Tenn 100 

Butte,  Mont 400 

As  a  result  of  oxygen-bearing  surface  waters  entering  the  ore 
body,  chemical  changes  begin,  oxidation  and  hydration  being 
important;  and  these  together  with  other  changes,  produce 
many  soluble  compounds. 

The  oxidation  of  pyrite,  for  example,  gives  sulphuric  acid, 
and  the  latter  is  active  in  the  formation  of  ferrous  and  ferric 
sulphates,  of  which  the  last-named  is  important  as  an  oxidizing 
agent. 

Not  all  of  the  sulphides  appear  to  be  attacked  with  equal  readi- 
ness, and  the  same  mineral  may  show  different  degrees  of  resist- 
ance under  different  conditions.  That  the  order  of  resistance 
does  not  seem  to  be  the  same  in  all  cases,  is  indicated  by  the 
first  table  on  page  478.  The  second  table  by  Emmons  (110), 
shows  in  an  interesting  manner  the  changes  that  have  taken  place 
in  the  weathering  of  the  copper  ores  at  Ducktown,  Tenn. 

Whatever  the  order  in  which  the  sulphides  succumb  to  the 
attacks  of  the  weathering  agents,  they  all  yield,  forming  new  com- 
pounds stable  under  surface  conditions,  and  sometimes  of  soluble 
character,  which  permits  their  removal. 

Among  the  compounds  found  in  the  oxidized  zone  are  the 
hydrous  oxides  of  iron,  hematite,  manganese  oxides,  free  gold  un- 
der favorable  conditions,  silver  chloride,  silicates,  carbonate  and 
sulphate  of  lead,  and  oxidized  compounds  of  zinc  and  copper. 

Tolman  (120)  claims  that  the  zone  of  weathering  can  be  divided 
into  three  subzones,  which  beginning  at  the  surface  are:  (1) 
Zone  of  complete  oxidation;  (2)  zone  of  complete  leaching;  and 
(3)  zone  of  oxide  enrichment  which  is  of  variable  thickness  and 
lying  immediately  above  the  sulphides. 


478 


ECONOMIC   GEOLOGY 


The  first  represents  complete  oxidation  and  includes  the  iron 
cap.     It   shows    limonite,    hematite,    residual   silica,    and   some- 


ORDER  OF  OXIDATION  OF  SULPHIDES,  ACCORDING  TO  SEVERAL  AUTHORITIES 


1 

2 

3 

4                      5 

6 

7 

8 

Iron 

Arsenopy- 
rite 

•  

.  .               



Pyrrhotite 

Marcasite 

Copper 

Pyrite 

Sphalerite 

Sphalerite 

Pyrite 

Chalcopy- 
rite 

i                       j 

Chalcocite 

Pyrrhotite 

Zinc 

Sphaleritv 

Chalcocite    Chalcocite 

Chalcocite 

Galena 

Galena 

Chalcopy- 
rite 

Bornite 

Lead 

Galena 

Bornite 

Silver 

Chalcocite 

Pyrrhotite 

Pyrrhotite 

Pyrite 

Millerite 





| 

Chalcopy- 
rite 

Chalcopy- 
rite 

Chalcopy- 
rite  and 
pyrite 

Chalcocite 





Pyrite 

Pyrite 

Pyrite 

Argentite 



Galena 
Sphalerite 

1.  Van  Hise,  Amer.  Inst.  Min.  Engrs.,  Trans., 'XXX:  101,  1901;  2.  Weed,  Ibid.,  XXX: 
429,1901;  3.  Lindgren,  U.  S.  Geol.  Surv.,  Prof.  Pap.,  43:  180,1905;  4.  Emmons  and 
Laney,  U.  S.  Geol.  Surv.,  Bull.  470:  151,  1911;  5.  Vogt,  Amer.  Inst.  Min.  Engrs., 
Trans.,  XXXI:  125,  1902;  6.  Gottschalk  and  Buehler,  Econ.  Geol.,  IV:  28,  1910; 
7.  Wells,  U.  S.  Geol.  Surv.,  Bull.  529:  76,  1913;  8.  Beck  (Weed),  Nature  of  Ore 
Deposits,  p.  337. 


CHEMICAL  CHANGES  BY  OXIDATION  PROCESSES  AT  DUCKTOWN,  TENN. 


la 

16 

2a 

26 

3 

SiO2                                   

22.44 

90.88 

9.95 

21.89 

-69 

Al2Os  

2.93 

11.87 

1.57 

3.45 

-   8.4 

Fe 

33.43 

135.39 

49.9 

109.78 

-25.6 

MgO 

3  15 

12.76 

(?) 

(?) 

-12.7 

CaO.  . 

8.28 

33  .  534 

.35 

77 

-32.7 

CO2 

2  85 

11.54 

-11.5 

S     

21.23 

85.98 

.65 

1.43 

-84.5 

MnO 

44 

1.78 

Cu  

2.45 

9.92 

.86 

1.89 

-  8 

Zn                                

2.79 

11.30 

-11.3 

H2O 

1  15.40 

22.88 

+33  .  88 

O  

i  21.38 

47.04 

+47.04 

Total  

99.99 

404  .  954 

100.06 

220.13 

-182.8 

1  HjO  and  O  are  estimated,  on  the  assumption  that  the  Fe  is  in  limonite. 

la,  Percentage  weight  of  constituents  of  primary  sulphide  ore,  Mary  mine;  1&,  percentage 
weight  times  specific  gravity  (4.05),  and  expresses  number  of  grams  in  100  cubic  centi- 
meters of  the  primary  ore;  2a,  chemical  composition  of  gossan,  26,  percentage  weight, 
times  its  specific  gravity  (2.2,  corresponding  to  39  per  cent  porosity) ;  3,  gain  and  loss 
of  the  several  constituents. 


ORE   DEPOSITS  479 

times  residual  gold,  as  well  as  silver  chloride.  Lead,  zinc,  and 
copper  oxidation  products  may  be  present.  The  second  is 
usually  somewhat  thoroughly  leached  of  its  metallic  contents,  but 
the  gold  and  less  often  silver  may  extend  down  into  it.  The 
third  may  contain  partly  oxidized  minerals,  and  include  native 
elements,  oxides,  carbonates  and  silicates  brought  from  above. 
Some  authors  do  not  agree  to  this  constant  zonal  division  of  the 
weathered  zone. 

Reactions  of  Oxidized  Zone.  —  The  reactions  that  take  place  in 
the  oxidized  zone  are  primarily  those  taking  place  between  the 
sulphides,  oxygen,  water,  carbon  dioxide  and  sulphuric  acid. 
These  may  be  followed  by  reactions  between  the  products  so 
formed  or  between  these  and  other  minerals,  the  result  in  some 
cases  being  the  formation  of  minerals  of  stable  and  slightly 
soluble  character,  which  are  evidence  of  weathering  reactions. 
Some  of  the  possible  reactions  follow : 

FeS2+4O  =  FeSO4+S, 

FeS2+7O.+H2O  =  FeSO4+H2SO4. 
FeS2+6O  =  FeSO4+SO2. 

Ferrous  sulphate,  however,  oxidizes  to  ferric  sulphate, 

2FeSO4+H2SO4+O  =  Fe2(SO4)3+H2O. 

But  the  ferric  sulphate  is  not  very  stable  near  the  surface, 
although  deeper  down  this  salt  together  with  ferric  chloride 
and  even  other  ferric  salts  may  remain  in  solution,  and  serve  as 
oxidizing  agents. 

Both  ferric  and  ferrous  sulphates  may  yield  limonite  as  follows: 

6FeSO4+3O+3H2O  =  2Fe2(SO4)3+Fe2(OH)6, 
Fe2  (SO4)  3 + 6H2O  =  2Fe  (OH)  3 + 3H2SO4} 
4Fe(OH)3  =  2Fe2O3+6H2O  =  2Fe2O3-3H2O+3H2O, 
2Fe2  (SO4)  3 + 9H2O  =  2Fe2O3  -  3H2O + 6H2SO4. 

As  evidence  of  the  oxidizing  effect  of  ferric  sulphate  we  have 

FeS2+Fe2(SO4)3  =  3FeSO4+2S  and 
2S+6Fe2(SO4)3+8H2O  =  12FeSO4+8H2S04. 

Again  the  ferric  sulphate  may  break  up  in  the  presence  of  water 
as  follows : 

Fe2(S04)3+H2O  =  2FeSO4+H2SO4+0. 


480  ECONOMIC  GEOLOGY 

the  atom  of  oxygen  liberated  being  free  to  attack  oxidizable  sub- 
stances. 

Another  important  role  played  by  ferrous  and  ferric  salts 
is  as  solvents  and  precipitants  of  gold  (Emmons). 

Gold  forms  no  insoluble  compound  in  the  oxidized  zone, 
and  it  is  not  soluble  in  sulphuric  acid;  nor  is  it  soluble  in  ferric 
sulphate  as  has  been  sometimes  stated. 

If  gold  is  in  solution  as  the  chloride,  it  is  precipitated  by  ferrous 
sulphate,  formed  in  manner  indicated  above,  but  if  much  man- 
ganese oxide  is  present,  the  ferrous  sulphate  is  oxidized  to  ferric 
sulphate,  which  does  not  precipitate  the  gold.  The  presence  of 
manganese  oxides  therefore  favors  the  dissolving  of  gold  in  acid 
solutions,  and  it  may  be  carried  downward.  On  meeting  a  reduc- 
ing environment,  however,  both  the  gold  and  manganese  are 
precipitated. 

Copper  sulphides  also  are  subject  to  oxidizing  action,  thus: 


=  CuSO4+FeSO4. 

At  times,  however,  a  reduction  may  occur,  as  shown  by  the  next 
equation  : 


The  copper  sulphate  may  be  held  in  the  oxidized  zone  as  a 
result  of  the  following  reactions: 

2CuSO4+2H2Ca(CO3)2 

=  CuC03(CuOH)2+3C02+2CaS04+H20, 
3CuSO4+3H2Ca(CO3)2 

=  2CuCO3(CuOH)2+3CaSO4+4CO2+2H2O, 


CuSO4+H2Ca(CO3)2+H4SiO4 

=  CuO-H4SiO4+CaSO4+H20+C02. 

If  zinc  sulphide  is  present  unaccompanied  by  pyrite  the  reaction 
will  be: 


If,  however,  pyrite  or  some  other  source  of  Fe2  (864)5  is  present, 
then  the  reactions  may  be  more  complicated,  as  shown  by  the 
following:1 

1  Wang,  Y.  T.,  Amer.  Inst.  Min.  Engrs.,  Bull.  Sept.,  1915,  1959. 


ORE   DEPOSITS  481 


=  2FeSO4+ZnSO4+S, 
3ZnSO4+3Na2CO3+4H2O  = 

=  ZnCO3-2Zn(OH)2H-3Na2SO4+2H2C03. 
ZnSO4+Ca(HC03)2  =  CaCO3+ZnCO3+H2SO4, 
ZnSO4  +  2NaHCO3  =  ZnCO3  +  Na2SO4  +  H2CO3  . 

Downward  Secondary  Sulphide  Enrichment  (106-122)  .  — 
In  many  ore  bodies  there  is  found  below  the  oxidized  zone  a 
second  one  in  which  the  ore  may  be  richer  than  that  above  or 
below  it.  This  zone,  known  as  the  secondary  sulphide  zone,  has 
been  enriched  by  the  deposition  of  secondary  sulphides,  is  of 
variable  thickness  and  richness,  and  represents  the  results  of 
important  processes  which  have  often  converted  a  non-workable 
ore  deposit  into  a  workable  one.1 

The  process  of  downward  sulphide  enrichment  briefly  stated 
is  as  follows  :  Ore  minerals  in  the  zone  of  weathering  become  con- 
verted into  soluble  compounds  (sulphates  chiefly),  as  explained 
above,  and  these,  on  being  carried  down  below  the  water  level, 
come  in  contact  with  unaltered  sulphides  or  other  reducing  agents 

1  There  is  likely  to  be  some  confusion  if,  in  the  future  different  investigators 
do  not  adhere  to  uniformity  in  usage  of  the  terms  primary  and  secondary.  In  this 
book,  the  term  secondary  sulphide  enrichment  is  applied  to  the  precipitation  of 
sulphides  below  the  oxidized  zone,  from  meteoric  waters,  penetrating  the  ore  body 
from  above,  and  taking  metallic  salts  from  the  oxidized  to  the  unoxidized  zone. 
Emmons  (HO)  applies  the  term  primary  to  al  1  ore  bodies  whose  chemical  and 
mineral  composition  have  remained  essentially  unchanged  by  superficial  agencies 
since  the  ores  were  deposited.  A  secondary  ore  he  classes  as  one  that  has  been 
altered  by  superficial  agencies. 

Tolman  (120)  classifies  the  minerals  of  an  ore  deposit  into  original  minerals  of 
the  rock;  primary  minerals  introduced  by  vapors  and  waters  of  deep-seated  or 
igneous  origin,  and  secondary  minerals  contributed  by  descending  surface  waters. 

Rogers  (117)  would  apply  the  name  secondary  to  a  mineral  formed  at  the 
expense,  or  by  the  replacement  of,  an  earlier  formed  mineral.  He  then  uses  the 
term  upward  secondary  enrichment  to  sulphides  deposited  from  rising  solutions, 
and  downward  secondary  enrichment  to  those  deposited  from  descending  solutions. 
These  two  terms  correspond  respectively  to  Ransome's  hypogene  and  supergene.* 

In  the  case  of  copper  ores  which  Rogers  has  studied  he  states  that  the  criteria 
of  downward  chalcocite  enrichment  may  be  summarized  as:  (1)  comparatively 
regular  replacement  along  anastomosing  channels;  (2)  the  presence  of  quartz 
veinlets  related  to  chalcocite  deposition;  (3)  the  association  of  melaconite  with 
chalcocite  along  veinlets.  Criteria  of  upward  chalcocite  enrichment  may  be 
summarized  as  follows:  (1)  Irregular  intricate  replacements;  (2)  the  presence 
of  so-called  graphic  intergrowths  of  bornite  and  chalcocite;  and  (3)  presence  of 
sericite  related  to  chalcocite  deposition.  Further  study  will  be  required  to  see 
whether  these  criteria  hold. 

*  U.  S.  Geol.  Surv.,  Bull.  540;  52,  1914. 


482  ECONOMIC  GEOLOGY 

which  reduce  them  again  to  insoluble  sulphides.  Thus  they 
bring  about  a  secondary  enrichment  of  the  ore  body. 

Important  as  this  process  is,  it  was  not  clearly  recognized  until 
a  comparatively  late  date,  when  the  writings  of  De  Launay  1  in 
France,  and  of  S.  F.  Emmons  (108),  Weed  (122),  and  Van  Hise 
(88),  in  the  United  States  did  much  to  increase  our  knowledge  of 
the  subject. 

All  ore  minerals  are  not  subject  to  the  process  of  secondary 
enrichment  as  outlined  above,  it  being  most  often  seen  in  ores  of 
copper,  gold,  and  silver,  and  to  lesser  extent  in  lead  and  zinc. 

Secondary-sulphide  enrichment  like  weathering  may  be  affected 
by  a  number  of,  and  sometimes  the  same  factors.  These  include 
climate,  altitude,  relief,  permeability,  geologic  history  of  the 
locality,  chemical  and  mineral  composition. 

Warm  climates  favor  chemical  reactions,  and  cold  climates  not  only 
retard  them,  but  freezing  temperatures  prevent  solution.  Secondary-enrich- 
ment zones  are  rare  in  north  latitudes  as  compared  with  southern  ones. 
If  formed  in  the  past  under  different  climatic  conditions  they  may  have  been 
removed  by  glaciation. 

Rainfall  in  abundance  may  be  favorable,  because  of  its  stimulating  effect 
on  groundwater  circulation,  but  scarcity  of  rainfall  does  not  preclude  the 
possibility  of  finding  secondary  ores,  as  a  moderate  supply  of  water  acting 
through  a  long  period  of  time  may  have  yielded  favorable  results. 

High  altitude  may  act  unfavorably  because  of  rapid  erosion  and  low 
temperatures,  but  under  favorable  conditions  enrichment  may  occur. 

Strong  relief  favors  deep  and  rapid  underground  circulation  and  hence 
may  cause  relatively  deep  enrichment,  while  in  a  base  leveled  area  the  cir- 
culation will  be  sluggish,  and  the  waters  will  not  descend  far  before  losing  the 
metals  dissolved  higher  up. 

Slow  erosion  means  a  longer  exposure  of  outcrop,  hence  long  weathering 
and  thorough  leaching,  but  if  the  process  continues  there  may  be  a  downward 
migration  of  both  the  oxidized  and  secondary  enrichment  zone;  the  products 
of  secondary  enrichment  may  therefore  be  derived  from  portions  of  the  ore 
body  long  since  removed. 

Permeability  is  an  essential  factor,  because  unless  the  solutions  can  pene- 
trate the  unweathered  part  of  the  ore  body,  secondary  enrichment  can  not 
occur.  The  permeability  may  be  due  to  original  porosity  of  the  ore,  or  to 
fractures  caused  by  post-mineral  movements.  Comparatively  small  openings 
sometimes  appear  sufficient  for  permeation. 

An  important  point  to  consider  is  the  past  topography,  for  the  enrich- 
ment may  have  taken  place  when  physiographic  conditions  were  quite  dif- 
ferent from  what  they  are  now,  and  hence  the  zone  of  secondary  sulphides 
shows  no  rational  relationship  to  the  present  land  surface. 

1  Les  variations  des  filons  metalliferes  en  profundeur,  Revue  g6nerale  des 
Sciences,  etc.,  Apr.  30,  1900,  No.  8. 


PLATE  XLII. — Photomicographs  of  polished  specimens  of  ore  from  Burro  Moun- 
tains, N.  Mex.,  showing  progressive  replacement  of  pyrite  (p)  by  chalcocite 
(cc.).  X40.  (R.  E.  Somers,  photo.) 

(483) 


484  ECONOMIC   GEOLOGY 

Under  normal  conditions  the  secondary  sulphides  would  be  deposited 
below  water  level,  but  subsequent  changes  in  the  lattei,  too  rapid  for  the 
chemical  changes  to  keep  pace  with,  may  result  in  secondary  sulphides 
extending  above  the  water  level. 

Criteria  of  Downward  Secondary  Sulphide  Enrichment  (ill,  116, 
117). — These  maybe  geologic,  mineralogic  and  textural.  Any 
one  alone  will  not  necessarily  afford  conclusive  evidence.  The 
geologic  criteria  include  suggestive  surface  conditions  such  as  a 
leached  ferruginous  gossan,  underlain  by  chalcocite  and  this  in 
turn  by  cupriferous  pyrite.  Or  the  weathered  zone  may  show 
argentiferous  galena,  more  or  less  altered  to  cerussite,  with 
deeper  down  the  appearance  in  increasing  quantities  of  sphalerite 
and  pyrite.  Assay  maps  of  an  ore  body  showing  a  lean  zone  above, 
passing  downward  into  one  of  relatively  greater  richness,  and 
this  in  turn  into  a  much  poorer  zone,  are  also  suggestive. 

It  is  difficult  to  name  any  mineral  as  distinctively  characteristic 
of  secondary  enrichment.  Even  chalcocite  which  at  one  time  was 
regarded  as  typical  of  this  process  is  now  known  to  be  formed  by 
primary  deposition. 

Textural  criteria  may  be  of  value.  Thus  we  find  veinlets  of 
rich  ore  in  leaner  material;  the  irregular  replacement  of  one  min- 
eral by  another  (Plate  XLII);  evidence  of  solution  followed 
by  deposition  of  fresh  material;  or  grains  of  primary  sulphide 
surrounded  by  secondary  ones,  as  chalcocite  surrounding  pyrite. 
No  one  of  these,  however,  should  be  used  alone. 

Chemistry  of  Secondary  Sulphide  Enrichment  (110,  119,  120).- 
The  exact  equations  of  secondary  sulphide  enrichment  are  not 
always  known.     Reference  has  already  been  made  to  some  of 
those  that  may  occur  in  the  zone  of  weathering,  resulting  in  the 
formation  of  soluble  sulphates,  chlorides  or  bicarbonates. 

Precipitation  below  the  water  level  may  be  due  to :  (1)  Reduc- 
tion of  sulphates  to  metallic  sulphides  by  carbonaceous  matter; 
(2)  Reduction  by  hydrogen  sulphide;  and  (3)  Reaction  of  salts 
with  sulphides. 

With  regard  to  the  precipitation  of  sulphates  by  sulphides,  it 
has  been  found  that  this  agrees  somewhat  closely  with  Schur- 
mann's  law  which  arranges  the  metallic  sulphides  in  a  series,  any 
member  of  which  will  be  precipitated  at  the  expense  of  any  sul- 
phide lower  in  the  series.1  His  series  was  Hg,  Ag,  Cu,  Bi,  Cd, 
Pb,  Zn,  Ni,  Co,  Fe,  Mn.  According  to  this  pyrite  for  example 

iLiebig's  Ann.  der  Chemie,  CCXLIX:  326,  1888. 


ORE   DEPOSITS  485 

would  precipitate,  copper,  lead,  zinc  or  others  in  the  series  above 
it.  Again  if  we  had  descending  solutions  carrying  copper,  lead 
and  silver,  the  order  of  precipitation  of  the  sulphides  of  these 
would  be  silver,  copper  and  lead  sulphides. 

The  order  of  precipitation  mentioned  above  may  not  hold 
under  all  conditions,  for  as  mentioned  by  Tolman  (120),  on 
account  of  mass  action,  a  strong  solution  of  a  metallic  salt, 
may  cause  a  precipitate  at  the  expense  of  a  member  of  the  series 
higher  up. 

Reactions  of  Secondary  Sulphide  Deposition  (110,  120).  —  Various 
reactions  have  been  written  to  explain  the  precipitation  of  metallic 
sulphides  in  the  zone  of  secondary  enrichment.  It  is  probable 
that  some  of  them  do  not  always  state  the  case  exactly,  and  that 
the  change  instead  of  being  a  simple  and  direct  one  may  involve 
several  intermediate  steps.  Thus,  for  example,  chalcocite  is 
found  as  a  secondary  mineral,  precipitated  by  pyrite,  but  careful 
work  by  Graton  and  Murdock  (ill),  corroborated  by  experi- 
mental work  performed  in  the  Carnegie  Geophysical  Laboratory 
at  Washington  1  has  shown  that  the  change  from  pyrite  to  chal- 
cocite is  not  a  direct  one,  but  that  there  may  be  intermediate 
stages  so  that  the  order  of  formation  in  some  cases  at  least  is: 
Pyrite—  »Chalcopyrite—>Bornite—>CoveHite—  ->  Chalcocite.  These 
changes  result  from  the  action  of  copper  sulphate  solutions  on 
sulphides,  and  at  low  temperatures  are  probably  exceedingly  slow. 

For  copper  some  of  the  enrichment  zone  reactions  published  are: 


=  Cu2S+2FeS04+3S,  or 
2O  =  7Cu2S+5FeSO4+12H2SO4, 
4CuSO4  +  FeS2  +  3SO2  +  6H2O  =  2Cu2S  +  FeSO4  +  6H2SO4, 

,  or 


=  CuFeS2-fFeSO4+SO2, 
CuS04+ZnS  =  CuS+ZnSO4, 
CuSO4+H2S  =  CuS+H2SCU. 


For  zinc  the  equations  may  be  :2 


,  or 
2ZnS04+FeS2+H2O  =  2ZnS+FeSO4+H2S04+O,   or 

1  Day,  Min.  and  Sci.  Pr.,  CX:   841,  1915. 

2  For  cases  of  secondary  sphalerite  see  Blow,  Amer.  Inst.  Min.  Engrs.,  Trans., 
XVIII:    172,  1890;    Graton,  13.  S.  G.  S.,  Bull.  430,  71:    1910;    Ransome,  Ibid., 
Prof.  Pap.  75:    169,  1911;   Finlayson,  Econ.  Geol.,  V:  417,  1910. 


486  ECONOMIC   GEOLOGY 

7ZnSO4+4FeS2+4H2O  =  7ZnS+4FeSO4+4H2SO4. 
For  lead  we  have 

PbSO4+FeS2+O2  =  9PbS+FeSO4+S02, 
PbSO4 + ZnS  =  PbS + ZnSO4 . 

It  is  difficult  to  distinguish  secondary  lead  and  zinc  minerals 
from  primary  ones,  because  they  are  the  same  in  each  case,  and 
while  they  no  doubt  occur,  few  well-defined  cases  have  been  de- 
scribed.1 

Secondary  silver  sulphides  undoubtedly  occur.  The  com- 
pounds said  by  Ransome  to  be  more  often  secondary  than  primary 
are  stephanite,  polybasite,  argentite,  pyrargyrite  and  proustite. 

Hydrothermal  Alteration  (13,  21,  103). — The  hot  ascending 
solutions  of  varying  composition  often  bring  about  a  most  pro- 
found alteration  of  the  rocks  which  they  traverse,  extracting  it 
may  be,  certain  elements  and  adding  others.  Indeed  in  some 
cases  the  alteration  is  so  extensive  that  the  rock  affected  bears 
no  resemblance  to  its  former  self. 

Alteration  is  usua]ly  most  intensive  along  the  fissures  which 
guided  the  solution,  but  if  the  rock  is  extensively  fractured  it 
may  be  affected  over  a  large  area. 

The  changes  produced  will  not  only  vary  with  the  composition 
of  the  solution,  but  also  with  the  temperature  and  pressure,  and 
in  some  cases  similar  changes  may  be  wrought  by  cold  solutions 
of  non-magmatic  character. 

The  types  of  hydrothermal  alteration  which  are  well  recognized 
are  propylitiaztion,  sericitization,  silitification,  alunitization  and 
greisenization. 

Two  of  these  may  sometimes  occur  in  tjhe  same  rock. 
.  Propylitization  (21,  103). — This  is  a  common  type  of  alteration, 
which  affects  chiefly  andesites  and  basalts,  but  rarely  rhyolites. 
It  results  in  a  change  of  the  silicates  to  abundant  chlorite,  and 
pyrite,  as  well  as  epidote  in  some  cases.  Carbonates  are  likewise 
formed,  and  in  some  cases  there  may  also  be  sericite.  The  rocks 
so  changed  are  usually  of  a  greenish-gray  color,  but  may  preserve 
their  original  texture.  The  process  may  involve  extraction  of 
soda  and  potash,  as  well  as  silica,  and  even  lime,  and  magnesia 
unless  carbonates  are  formed,  while  the  additions  consist  chiefly 
of  sulphur  and  water. 

1  See  Finlayson,  Econ.  GeoL,  V:  421,  1910;  Weed,  Amer.  Inst.  Min.  Engrs., 
XXX:  424,  1901;  Irving  and  Bancroft,  U.  S.  G.  S.f  Bull.  478:  97,  1911. 


ORE   DEPOSITS  487 

Propylitization  is  probably  a  somewhat  shallow  process,  and 
is  a  common  accompaniment  of  some  western  gold  and  silver 
veins.  It  is  found  in  the  rocks  bordering  the  veins  at  Virginia 
City  and  Tonopah,  Nev.,  Cripple  Creek,  Colo.,  and  other  places. 

Sericitization.  —  This  is  a  common  type  of  hydrothermal  altera- 
tion, which  is  often  seen  near  veins,  but  may  pass  outward  into 
propylitic  alteration.  The  rocks  so  altered  are  white  or  light 
yellow  in  color,  and  the  mass  often  appears  clay-like.  Indeed 
sericite  masses  are  sometimes  mistaken  for  kaolin,  and  it  is  diffi- 
cult to  distinguish  sericite  from  kaolinite,  under  the  microscope. 

Sericitization  involves  a  loss  of  soda  and  a  gain  of  potash. 
Silica  may  be  reduced  or  increased  in  amount,  and  carbonates 
may  be  formed,  while  pyrite  is  usually  added.  The  resultant 
product  is  a  fine-grained  mixture  of  sericite,  adularia  and  pyrite, 
with  sometimes  calcite  and  quartz,  the  first-named  of  these  being 
developed  from  both  quartz  and  feldspar.  Close  to  the  vein, 
silicification  sometimes  overshadows  Sericitization.  The  latter 
process  may  take  place  in  veins  of  both  shallow  and  intermediate 
depth;  moreover  although  chlorite  may  be  developed  first, 
sericite  may  crowd  it  out  later  (Butte,  Mont.). 

Silicification.  —  This  is  also  a  common  form  of  alteration  associ- 
ated with  the  deposition  of  ores,  being  more  often  noticed  in  acid 
than  in  basic  rocks.  Rhyolites  may  often  show  it,  both  the 
groundmass  and  phenocrysts  being  affected.  At  Goldfield,  Nev., 
the  silicified  ledges  so  prominently  associated  with  the  ore  bodies 
are  formed  by  the  alteration  of  andesite  (Plate  LXVIII,  Fig.  2). 
The  quartz  thus  formed  is  of  cherty  character,  but  the  original 
structure  of  the  rock  may  be  clearly  preserved.  Limestones  and 
other  calcareous  rocks  may  also  be  silicified,  as  in  some  contact 
metamorphic  deposits.  (See  Bisbee  and  Miami,  Arizona.) 

In  some  cases  silicification  may  be  brought  about  by  meteoric 
waters  (southwest  Missouri  zinc  district) . 

Alunitization.  —  This  type  of  alteration,  which  is  not  a  very 
common  one,  was  first  noticed  at  Goldfield,  Nev.,  where  the 
feldspars  have  been  somewhat  extensively  altered  to  alunite. 
It  is  a  change  that  takes  place  at  shallow  depths,  and  is  thought 
to  be  due  to  the  action  of  descending  sulphuric  waters,  meeting 
ascending  alkaline  ones. 

The  alunite  at  Goldfield  occurs  not  only  as  a  massive  crystalline 
constituent  of  the  altered  rocks,  but  also  intergrown  with  pyrite, 
gold,  tellurides,  and  other  minerals  of  the  ore. 


488  ECONOMIC  GEOLOGY 

Alunitization  has  since  been  noticed  at  a  number  of  other 
western  localities.  (See  references  under  Potash.) 

Greisenization.  —  The  granite  walls  of  many  tin  veins  show  a 
strong  and  characteristic  alteration,  the  feldspar  and  muscovite 
being  attacked  by  water  vapors  carrying  fluorine  and  boric  acid, 
resulting  in  the  development  of  a  mass  of  quartz,  topaz,  tour- 
maline and  lepidolite,  to  which  the  name  greisen  is  applied. 
Cassiterite  may  also  be  present  in  the  altered  wall  rock. 

Value  of  Ores.  —  The  terms  rich  and  poor,  as  applied  to  ores, 
are  used  with  great  frequency,  although  most  indefinite  and  often 
meaningless.  Under  very  favorable  conditions  it  is  possible  to 
profitably  work  an  ore  of  given  value  at  one  locality,  while  if  found 
under  other  less  favorable  conditions  at  another  point  it  might  be 
almost  worthless. 

Those  who  have  not  given  special  study  to  ore  deposits  often 
fail  to  realize  that  in  the  majority  of  ores  the  percentage  of  metal 
contained  in  the  ore  falls  considerably  below  the  theoretic  per- 
centage of  the  metallic  contents  in  the  ore-bearing  minerals,  due 
of  course  to  the  presence  of  a  greater  or  less  quantity  of  gangue 
minerals  which  tend  to  dilute  the  metallic  values  of  the  vein. 
Many  low-grade  lead  ores  are  profitably  mined  because  their  gold 
and  silver  contents  more  than  pay  the  cost  of  metallurgical  treat- 
ment. In  many  cases  the  metallic  contents  of  the  ore  is  increased 
by  mechanical  concentration  or  by  roasting  (in  the  case  of  sul- 
phides), or  both,  before  the  ore  is  smelted. 

Allowable  Minimum  of  Metal  in  an  Ore  (52).  —  Iron  ores  are  of  little 
value,  wherever  they  may  be  located,  unless  they  contain  at  least  30  per 
cent  of  iron  when  charged  into  the  furnace. 

Copper  has  an  average  minimum  of  about  2  per  cent,  but  the  Lake 
Superior  ores,  because  of  their  peculiar  characteristics,  can  be  operated  on  a 
lower  percentage.  Many  of  the  western  disseminated  copper  sulphides, 
which  are  worked  on  such  an  extensive  scale,  do  not  average  much  over 
2  per  cent.  In  the  case  of  these  low-grade  ores  the  metallic  contents  are 
raised  by  mechanical  concentration  or  roasting,  or  both,  before  entering  the 
furnace. 

Lead.  —  In  southeastern  Missouri  lead  ores  are  profitably  mined  when 
carrying  as  little  as  5  to  10  per  cent  metal,  but  the  concentration  raises  the 
rercentage  up  to  65  or  70  per  cent. 

Zinc  ores  on  entering  the  furnace  should  have  a  minimum  of  25  to  30  per 
cent  zinc,  but  the  contents  are  sometimes  raised  to  60  or  more  per  cent  by 
concentration,  the  concentrates  being  sold  on  a  percentage  basis.  Some  of 
the  Missouri  zinc  ores  as  mined  run  as  low  as  3  per  cent  zinc. 

Gold  and  Silver. — The  metallic  contents  of  these  ores  are  expressed,  not 


ORE  DEPOSITS  489 

in  percentages,  but  in  troy  ounces  per  ton,  a  troy  ounce  in  a  ton  being  -^ 
per  cent.  The  market  value  of  silver  is,  in  round  numbers,  50-60  cents  per 
ounce,  while  gold  in  round  numbers  is  figured  at  $20  per  ounce. 

Silver  rarely  occurs  alone,  and  the  ore  may  be  treated  primarily  for  its 
associated  lead  and  copper. 

In  the  base  ores  there  should  be  enough  silver  to  yield  a  minimum  of  $5 
or  10  ounces  in  the  resulting  ton  of  copper,  to  make  its  extraction  profitable. 
If  now  in  a  5  per  cent  copper  ore  20  tons  of  ore  are  concentrated  to  1  ton 
of  pig  copper  (or  21  tons,  allowing  for  losses),  it  follows  that  we  need  10 
ounces  of  silver,  in  21  tons  of  ore,  or  a  minimum  of  |  ounce  silver  per  ton, 
or  gio  per  cent. 

Under  favorable  conditions  gold  can  be  extracted  down  to  ^  ounce  per 
ton  or  -3^00  per  cent.  It  usually  runs  from  £  to  1  ounce. 

In  some  copper  or  lead  ores  the  saving  of  even  -^  ounce  gold  may  be  an 
object.  In  gravels,  a  gold  content  of  as  low  as  7  to  10  cents  per  cubic  yard 
(¥tro  to  3^-0  ounce)  may  be  saved. 

Tin.  —  For  this  metal  the  crude  ore  commonly  ranges  from  1.5  to  3  per 
cent,  but  by  concentration  it  can  be  raised  to  70  per  cent. 

Nickel  should  reach  2  to  5  per  cent  in  the  crude  ore. 

Platinum.  —  Owing  to  the  scarcity  of  this  metal,  few  figures  aie  avail- 
able, but  in  Russia  placers  are  worked  which  carry  -£$  ounce  per  cubic  yard, 
which  is  the  equivalent  of  -fa  ounce  per  ton  or  5.5  hundred- thousandth  per- 
cent. 

Manganese  to  be  considered  of  commercial  grade  must  contain  at  least 
35  per  cent  manganese  and  otherwise  conform  to  the  specifications  of  the 
trade  in  which  they  are  used. 

Chromium  ore  should  carry  40  per  cent  of  the  metal. 

Classification  of  Ore  Deposits. — Many  attempts  have  been 
made  to  develop  a  suitable  classification  of  ore  deposits,  and  many 
schemes  have  been  suggested  (46).  These  are  usually  based  either 
on  form,  mineral  contents,  or  mode  of  origin.  The  first  is  perhaps 
the  most  practical  from  the  miner's  standpoint,  the  second  is  un- 
desirable because  several  kinds  of  ore  may  often  be  found  in  the 
same  ore  body,  while  the  third  is  the  most  scientific,  and  is  of 
value  to  the  mining  geologist  and  engineer. 

Those  desiring  to  look  into  this  phase  of  the  subject  in  more 
detail  are  referred  to  the  bibliography  at  the  end  of  this  chapter, 
especially  the  papers  by  Kemp  (46),  Posepny  (68),  Van  Hise  (2), 
and  Vogt  (13). 

Two  classifications  are  given  here,  viz.,  those  of  W.  H.  Weed 
and  W.  Lindgren.  Both  are  based  in  part  at  least  on  genetic 
characters,  but  the  second  goes  a  little  farther,  and  attempts 
to  indicate  more  definitely  the  physical  conditions  of  deposition. 


490  ECONOMIC  GEOLOGY 

CLASSIFICATION  OF  ORE  DEPOSITS  (AFTER  WEED) 

A.  Igneous,  magmatic  segregation, 
(a)  Siliceous. 

1.  Masses,  Aplitic  masses.     Ehrenberg,  Shartash. 

2.  Dikes,  Beresite  or  Aplite.     Berezovsk. 

3.  Quartz  veins.     Alaska,  Randsburg,  Black  Hills. 
(6)  Basic. 

1.  Peripheral  masses.     Copper,  iron,  nickel.     (Sudbury,  Ont.) 

2.  Dikes,  titaniferous  iron.     Adirondacks,  Wyoming. 

B.  Igneous    emanations.     Deposits     formed     by    gases     above    or    near 

the  critical  point,  e.g.  365°  C.  and  200  atmospheres  for  H2O. 
(a)  Contact-metamorphic  deposits. 

1.  Deposits  confined  to  contact.     Magnetite  deposits   (Hanover, 

N.  Mex.),  chalcopyrite  deposits,  Kristiania  type,  gold  ores, 
Bannock,  Ido.,  type. 

2.  Deposits    impregnating    and    replacing  beds  of    contact    zone. 

Chalcopyrite  deposits,  pyrrhotite  ores,  magnetite  ores,  Can- 
anea    type,  gold  tellurium  ores,   Elkhorn  type,  arsenopyrite 
ores,  Similkameen  type. 
(6)  Veins  closely  allied  to  magmatic  veins  and  to  Division  D. 

1.  Cassiterite.     Cornwall. 

2.  Tourmaline  copper.     Sonora. 

3.  Tourmaline  gold.     Helena,  Mont.,  Minas  Geraes,  etc. 

4.  Augite  copper,  etc.     Tuscany. 

C.  Fumarolic  deposits. 

(a)  Metallic  oxides,  etc.,  in   clefts   in  lava.     No   commercial  impor- 
tance.    Copper,  iron,  etc. 

D.  Gas-aqueous   or   pneumato-hydato-genetic   deposits,   igneous   emana- 

tions, or  primitive  water  mingled  with  ground  water, 
(a)  Filling  deposits. 

1.  Fissure  veins. 

2.  Impregnation  of  porous  rock. 

3.  Cementation  deposits  of  breccia. 
(6)  Replacement  deposits. 

1.  Propylitic.     Comstock. 

2.  Sericitic   kaolinic,  calcitic,  Copper  silver,  Silver  lead.      Glaus- 

thai.     De  Lamar,  Ido. 

3.  Silicic  dolomitic,  silver  lead,  Aspen. 

4.  Silicic  calcitic.     Cinnabar,  California. 

5.  Sideritic  silver  lead.     Cceur  d'Alene,  Slocan,  Wood  River. 

6.  Biotitic  gold  copper.     Rossland,  Brit.  Col. 

7.  Fluoric  gold  tellurium.     Cripple  Creek,  Colo. 

8.  Zeolitic.     Michigan  copper  ores. 

Structure  Types  of  Above 

Fissure  veins.     (San  Juan,  Colo.) 
Volcanic  stocks,  Nagyag.     Cripple  Creek. 
Contact  chimneys.     Judith. 


ORE   DEPOSITS  491 

Dike  replacements  and  impregnations. 
Bedding  or  contact  planes.     Mercur. 

Axes   of  folds,    synclinal   basins,    anticlinal   saddles.     Bendigo, 
Elkhorn. 

E.  Meteoric  waters.     (Surface  derived.) 
(a)  Underground. 

1.  Veins.     (Wisconsin  lead  and  zinc.) 

2.  Replacements.     Iron  ores,  Michigan  ;  lead,  zinc. 

3.  Residual.      Gossan  iron  ores,  manganese  deposits.       (Virginia.) 
(6)  Surficial. 

1.  Chemical.     Bog  iron  ores,  sinters.     Some  bedded  iron  ores,  etc. 

(Clinton  ore.) 

2.  Mechanical.     Gold  and  tin  placers. 

F.  Metamorphic    deposits.     Ores     concentrated     from     older    rocks    by 

metamorphism,  dynamo  or  regional. 

CLASSIFICATION  OF  ORE  DEPOSITS  (AFTER  LINDGREN) 

I.  Deposits  produced  by  mechanical  processes  of  concentration.     (Tempera- 
ture and  pressure  moderate.) 
Ex.  Placers  of  gold,  platinum,  etc. 

II.  Deposits  produced  by  chemical  processes  of  concentration.     (Tempera- 
ture and  pressure  vary  between  wide  limits.) 

A.  In  bodies  of  surface  water. 

1.  By  interaction  of  solutions:  f    Temp., 

a.  Anorganic  reactions.     Clinton  iron  ore.  I    0°-70°rb. 

b.  Organic  reactions.     Ex.  Bog  iron  ore.  Pressure 

2.  By  evaporation  of  solvents.  (No  metallic  examples).  I  moderate. 

B.  In  bodies  of  rocks. 

1.  By  concentration  of  substances  contained  in  the  geological 
body  itself. 

a.  Concentration  by  rock  decay  and  residual     o°-100°it 

weathering  near  surface.     Ex.  Residual  j  pressure 
iron  and  manganese  ores.  [    moderate. 

b.  Concentration  by  ground  water  of  deeper     o°-100°± 

circulation.      Ex.    Lake   Superior   iron  1      pressure* 

ores  E    moderate. 

r  Temp,  up 

c.  Concentration    by    dynamic    and    regional       tQ  ^QQO 

metamorphism.       Ex.     Fahlbands     in  j  pressure 
some  schists?                                                [        ^igh 

t      Temp., 

d.  Zeolitization  of  surface  lavas.     Ex.  L.  Su-  I  50°-300°. 

perior  copper  ores.  Pressure 

I   moderate. 


492 


ECONOMIC   GEOLOGY 


Pressure 
moderate. 


2.  Concentration  effected  by  introduction  of  substances  foreign 
to  the  rock. 

a.  Origin  independent  of  igneous  activity. 

r      Temp., 
By  circulating    atmospheric    waters    at  [      fn  1()0o 

moderate  or  slight  depth.     Ex.  Miss, 
valley  lead  and  zinc  ores. 

b.  Origin  dependent  upon  the  eruption  of  igneous  rocks. 

a.  By  hot  ascending  waters  of  uncertain  origin,  but 
charged  with  igneous  emanations. 

Temp., 

1.  Deposition  and  concentration  at  5()°=fc- 
slight  depth.  Ex.  Goldfield,  j  150 °±. 
Nev.  Pressure 

moderate. 
Temp., 

300°±. 

Pressure 

high. 

Temp., 

300°±- 

500 °=fc. 

Pressure 

very  high. 

Temp., 
probably 

300°±- 

800°. 

Pressure 

very  high. 

Temp., 

400°=b. 


2.  Deposition  and  concentration  at 

intermediate  depth.  Ex. 
Leadville,  Colo.;  Cobalt, 
Ont. 

3.  Deposition  and  concentration  at 

great  depth  or  at  high  tem- 
perature and  pressure. 
Ex.  Tin  veins;   Ontario  quartz 

veins. 
b.   By  direct  igneous  emanations. 

1.  From  intrusive  bodies.  Contact 
metamorphic  deposits  and 
allied  veins. 


2.  From    effusive    bodies, 
mates,    fumaroles. 
deposits. 


Subli- 
No    ore 


Pressure 
atmos- 
pheric    to 
moderate. 
C.  In  magmas,  by  processes  of  differentiation. 

a.  Magmatic    deposits    proper.     Temp.,    700°-1500°.     Pressure 

high. 
Ex.  Titaniferous  iron  ore.     Chromite. 

b.  Pegmatites.     Temp,  about  575°.     Pressure  very  high. 

Ex.  Molybdenum  ore. 

Metallogenetic  Epochs. — The  term  metallogenetic  epoch  refers 
to  a  period  of  time  during  which  a  deposition  of  metals  was  taking 
place,  and  usually  accompanied  or  immediately  followed  periods 


ORE  DEPOSITS  493 

of  igneous  activity.  This  process  has  been  active,  during  a  number 
of  periods  in  the  past,  as  shown  by  the  geologic  records,  and  the 
available  data  for  North  America  have  been  summarized  by 
Lindgren  as  follows  (62). 

Pre-Cambrian  Period.  —  The  pre-Cambrian  rocks,  which  under- 
lie a  number  of  extensive  areas  in  the  United  States,  include  not 
only  metamorphosed  schists  and  gneisses,  but  also  various  types 
of  intrusives,  the  characteristic  metals  being  iron,  copper,  nickel, 
gold,  and  silver.  Lead  and  zinc  are  less  abundant  than  they  are 
in  the  later  periods,  while  quicksilver  and  antimony  are  rare. 

The  ilmenites  and  magnetites  of  the  eastern  states  are  chiefly 
of  igneous  origin,  while  the  hematites  of  Lake  Superior  are  partly 
igneous  and  partly  sedimentary,  but  subsequently  oxidized  and 
concentrated  by  surface  waters,  a  process  which  is  believed  to  have 
gone  on  in  pre-Cambrian  times,  The  copper  and  nickel  ores  are 
associated  with  basic  igneous  rocks,  some  of  these,  as  in  Michigan, 
being  of  effusive  nature.  This  copper  concentration  Lindgren 
suggests  must  have  gone  on  in  pre-Cambrian  times,  following  the 
close  of  Keeweenawan  (Algonkian)  volcanic  activity.  Of  similar 
age  are  the  cobalt-silver  veins  of  Ontario.  The  auriferous-quartz 
veins  of  the  southern  states,  whose  deposition  followed  that  of 
granitic  intrusions  in  schists,  are  also  to  be  placed  here,  although 
some  writers  would  date  them  later. 

In  the  Cordilleran  region  the  pre-Cambrian  was  productive  of 
gold  and  copper  deposits,  which  are  found  at  many  points  from 
South  Dakota  and  Wyoming  to  Arizona.  These  gold  ores  are 
usually  lenticular  quartz  veins  in  schists,  associated  with  such 
gangue  minerals  as  tourmaline,  garnet,  etc.  The  copper  ores  often 
contain  chalcopyrite,  and  form  veins  or  irregular  masses,  which 
are  probably  of  magmatic  origin,  and  have  been  modified  by 
dynamo-metamorphism.  Sphalerite  may  accompany  the  chal- 
copyrite, but  lead  is  almost  entirely  wanting. 

In  Ontario  a  careful  study  of  the  pre-Cambrian  rocks  by  Miller 
and  Knight 1  (66)  has  shown  the  possibility  of  recognizing  at 
least  five  metallogenetic  epochs  as  follows: 

1.  Grenville.  — Epoch  of  extensive  deposition  of  "  iron  forma- 
tion," as  a  chemical  precipitate  among  other  sediments. 

2.  Timiskanian.  —  Epoch  of  minor  deposition  of  "  iron  forma- 
tion "  as  a  chemical  precipitate. 

3.  Algoman.  —  Epoch  following  granite  intrusions,  of  gold  at 

1For  classification  used  here,  see  Geol.  Soc.  Amer.,  Bull.  XXVI:  87,  1915. 


494  ECONOMIC   GEOLOGY 

Porcupine  and  other  loca  ities,  and  of  auriferous  mispickel.  Pre- 
ceding granite  intrusions,  basic  intrusions  of  probable  post- 
Timiskanian  age,  gave  rise  to  nickel,  titaniferou;?  and  non-titanif- 
erous  magnetites  and  chromite. 

4.  Animikean.  —  Epoch  of  deposition  of  "  iron  formation  "  as  a 
chemical  precipitate. 

5.  Keweenawan.  —  Epoch  following  basic  intrusions  of:    a.  Sil- 
ver, cobalt,  nickel  and  arsenic  at  Cobalt  and  elsewhere;  b.  Nickel 
and  copper  at  Sudbury  and  copper  elsehwere. 

Paleozoic.  —  During  this  time  a  number  of  granitic  intrusions 
occurred  from  New  York  and  New  England  northward  to  Quebec 
and  Nova  Scotia,  and  these  were  accompanied  by  the  formation 
of  some  gold-quartz  veins;  but  little  metallization  occurred  in  the 
West  during  this  period. 

Two  periods  of  iron-ore  formation  occurred  during  Paleozoic 
time  in  the  East.  One  of  these  was  in  the  Silurian,  when  the  per- 
sistent beds  of  low-grade  Clinton  hematite  were  formed;  the  other 
was  during  the  Carboniferous,  when  the  layers  of  carbonate  black- 
band  ores  were  deposited. 

Mesozoic.  —  During  the  Triassic,  small  deposits  of  copper  and 
iron  ores  were  formed  in  the  eastern  states,  along  the  contact  of  the 
trap  sheets  and  sedimentary  rocks.  The  deposits  were  in  part 
veins  and  in  part  of  contact-metamorphic  character. 

In  the  West  important  accumulations  of  ores  were  beginning, 
for  during  the  Triassic  there  began  a  series  of  eruptions  which 
continued  through  the  Jurassic,  the  products  of  these  being  basic 
lavas  which  were  extruded  from  California  to  Alaska.  The  metal- 
lization accompanying  or  following  these  yielded  copper  deposits, 
which  include  some  of  those  found  in  California,  British  Columbia, 
and  those  of  the  Copper  River  region  in  Alaska. 

Another  important  metallization  epoch  followed  the  intrusion 
of  the  great  early  Cretaceous  quartz-monzonite  or  grano-diorite 
batholiths  of  the  Pacific  coast. 

These  injections  were  of  vast  extent,  one  batholith  extending 
through  California,  and  another  from  Washington  up  through 
British  Columbia  to  Alaska,  while  other  smaller  masses  occur  in 
several  of  the  -western  states.  These  intrusions  were  followed  by 
intense  metallization,  mineral  deposits  being  formed  in  abundance 
around  the  margin  of  the  batholiths,  as  in  the  gold  belt  of  Cali- 
fornia. Gold  was  the  chief  metal  formed,  with  copper  next.  Along 
the  Pacific  coast,  where  there  is  little  limestone  in  the  intruded 


ORE   DEPOSITS  495 

sediments,  lead  is  rarely  found,  but  in  the  interior  (Nevada  and 
Idaho)  where  limestones  were  present,  lead  and  zinc  both  occur. 
Silver  is  everywhere  present,  but  is  rarely  important  unless  asso- 
ciated with  lead;  arsenic  and  antimony  are  rare;  and  mercury  is 
wanting  in  commercial  quantities. 

Early  Tertiary.  —  About  this  time,  perhaps  a  little  earlier,  or 
a  little  later,  important  concentrations  of  lead  and  zinc  took  place 
in  the  Mississippi  Valley,  but  they  appear  to  have  been  independ- 
ent of  igneous  intrusions,  and  are  thought  by  most  geologists  to 
represent  the  work  of  surface  waters,  the  ultimate  source  of  the 
metals  being  the  pre-Cambrian  rocks. 

At  the  close  of  the  Cretaceous  violent  outbursts  began  along 
the  eastern  margin  of  the  Cordilleran  region,  the  magmas  being 
of  intermediate  character  and  laccolithic  form.  They  occur  from 
British  Columbia  through  Montana,  Colorado,  New  Mexico,  and 
eastern  Arizona  down  into  Mexico. 

There  ensued  then  another  or  third  epoch  of  Cordilleran  metal- 
lization, during  which  many  contact-metamorphic  deposits  and 
veins  were  formed  around  the  margins  of  the  laccoliths.  Gold  and 
silver  are  the  characteristic  metals,  with  abundant  lead  and  zinc, 
especially  where  the  intrusions  cut  limestones.  The  latter  may  also 
show  copper  and  iron  along  the  contact.  Arsenic  and  antimony 
are  more  common  than  they  were  in  the  earlier  epochs,  but  mercury 
is  still  rare. 

Late  Tertiary.  —  After  a  period  of  mountain-making  disturbances, 
uplift,  warping,  and  dislocations,  there  were  extruded  a  series  of 
lava  flows  which  spread  over  a  large  area  in  the  far  West,  and  are 
prominent  in  California,  Washington,  Oregon,  Idaho,  Colorado, 
Utah,  Nevada,  New  Mexico,  and  Arizona.  Andesites  and  rhyo- 
lites  predominate.  This  was  accompanied  by  a  fifth  metallization, 
whose  characteristic  metals  are  gold  and  silver,  forming  deposits 
often  of  great  richness ;  lead  and  zinc  are  not  abundant,  except 
in  limestone,  and  neither  is  copper.  Tellurium  and  antimony  are; 
not  that  they  are  absent  in  older  metallizations,  but  the  tellurium 
seems  to  be  especially  characteristic  of  this  epoch.  The  metallic 
deposits  seem  to  be  somewhat  restricted,  occurring  mainly  near 
the  foci  of  igneous  activity. 

Post- Pliocene.  —  There  came  finally  an  epoch  of  metallization 
at  a  late  date,  restricted,  however,  to  the  Pacific  coast  line,  and 
characterized  by  the  mercury  deposits  of  the  Pacific  coast  belt. 

Cretaceous  or  Later  Copper  Epochs.  —  These,  being  of  wide  time 


496 


ECONOMIC   GEOLOGY 


range,  cannot  be  included  in  the  previous  classes.  They  represent 
disseminations  of  copper  in  sandstones,  shales  or  conglomerates, 
and  carry  in  most  cases  primary  chalcocite  with  a  little  silver. 

Summary.  —  The  following  table  of  Lindgren  summarizes  the 
conditions  for  the  western  states : — 


PRINCIPAL 
METALS 

PRINCIPAL  ROCKS 
ASSOCIATED  WITH 
DEPOSITS 

1.  Deposits  of  the  pre-Cam- 
brian  period    .... 

Gold  and  copper  .     . 

Granites, 
{  diorites,  gabbro 

2.  Deposits     of     the     early 
Mesozoic  epoch  .     .     . 

Copper       I     .    '.     . 

Basalt,  diabase, 
{  gabbro 

3.  Deposits  of  the  late  Meso- 

Gold      .     .     . 

J  Granodiorite, 

zoic  epoch       .     .     .     . 

4.  Deposits  of  the  early  Ter- 
tiary epoch      .     .     .     . 

Gold,  silver     .     .     . 
Copper,  lead,  zinc    . 

['quartz-monzonite 
'  Granodiorite, 
quartz-monzonite, 
monzonite 

5.  Deposits  of  the  late  Ter- 
tiary epoch      .... 

Gold,  silver     .     .     . 

f  Andesite 
{  Rhyolite, 

6.  Deposits     of     the     Post- 
Pliocene  epoch     .     «-    . 

Quicksilver      .     .     . 

Basalt 

7.  Cretaceous  or  later  con- 
centrations in  sedimen- 
tary rocks  .     .     ... 

Copper  .     .     . 

f  Sandstone,  shale, 
[  conglomerate 

Metallographic  Study  of  Ores  (14). — Owing  to  the  opaque 
character  of  most  ore  minerals  these  cannot  be  examined  in  thin 
sections  by  transmitted  light,  as  is  done  with  non-metallic 
mineral?. 

Another  method  of  study  has  therefore  been  developed  in  recent 
years,  and  consists  in  examining  polished  surfaces  of  the  ore  under 
the  microscope  by  reflected  light.  By  this  means  the  relation- 
ships of  the  different  metallic  minerals  in  the  ore  can  be  quite 
satisfactorily  studied,  and  differentiated  by  means  of  their  color, 
microchemical  tests,  etc.  Plate  XLII,  shows  a  series  of  ore  speci- 
mens examined  and  photographed  in  the  manner  described  above. 
This  method  of  study  has  been  most  helpful  in  studying  genetic 
problems,  secondary  enrichment  processes,  etc. 


ORE  DEPOSITS  497 


REFERENCES  ON  ORE  DEPOSITS 

GENERAL  WORKS.  1.  Bain  and  Others,  Types  of  Ore  Deposits.  San  Fran- 
cisco, 1911.  2.  Beck,  Lehre  von  den  Erzlagerstatten.  Berlin,  3d  ed., 
1909.  Translation  by  Weed.  New  York,  1909.  3.  Berg,  Mikroskopische 
Untersuchung  der  Erzlagerstatten.  Berlin,  1915.  4.  Bergeat,  Die 
Erzlagerstatten.  Leipzig,  1904.  5.  Clarke,  U.  S.  Geol.  Surv.,  Bull. 
616:  626,  1916.  6.  v.  Cotta,  Die  Lehre  von  den  Erzlagerstatten.  Frei- 
berg, 1859.  7.  Farrell,  Practical  Field  Geology.  New  York,  1912. 
8.  Fuchs  et  De  Launay,  Traite  des  Gites  Mineraux  et  Metalliferes. 
Paris,  1893.  9.  Gunther,  Examination  of  Piospects.  New  York,  1912. 
10.  Hayes,  Handbook  for  Field  Geologists.  New  York,  1909.  11. 
Kemp,  Ore  Deposits  of  United  States  and  Canada.  New  York,  1906. 

12.  Krusch.  Die    Untersuchung   und   Bewertung   von   Erzlagerstatten. 
Stuttgart.     13.  Lindgren,    Mineral   Deposits.     New   York,    1913.     14. 
Murdock,  Microscopic  Examination  of  Opaque  Minerals.     New  York, 
1916.    15.  Parks,  A  Textbook  of  Mining  Geology.     London,  1914.     15a. 
Posepny,  Amer.  Inst.  Ming.  Engrs.,  Trans.,  XXIII:    197,  1894.     (Gen- 
esis of  ore  deposits.)     16.  Phillips,  Treatise  on  Ore  Deposits.     London, 
1884;    2d  edition  rewritten   and   enlarged  by  Henry  Louis,  1896.     17. 
Thomas  and  MacAlister,  The  Geology  of  Ore  Deposits,  London,  1909. 

18.  Sandberger,    Untersuchungen   liber    Erzgange.     Wiesbaden,    1882. 

19.  Spurr,  Geology  Applied  to  Mining.   New  York,  1904.  !  20.  Van  Hise, 
Treatise  on  Metamorphism,  U.  S.  Geol.  Surv.,  Mon.  XLVII,   1905. 
21.  Vogt,    Krusch   and   Beyschlag,    Die    Lagerstatten   der   Nutzbaren 
Mineralien  und  Gesteine.     Stuttgart,  1909.     Translation  by  Truscott, 
London,  1914.     22.  Whitney,  Metallic  Wealth  of  United  States.     Phil- 
adelphia, 1854. 

Papers  of  Special  Character 

CLASSIFICATIONS.     23.  For  a  statement  of  the  many  proposed  see  Refs.  2,  11, 

13,  21,  above. 

CONTACT-METAMORPHIC  DEPOSITS.     24.  Barrell,  A.  J.  S.,  XIII:   279,  1902. 

25.  Barrell,  U.  S.  Geol.  Surv.,  Prof.  Pap.  57,  1907.    (Marysville,  Mont.) 

26.  Crosby,   Amer.   Inst.   Min.  Engrs.,   Trans.,   XXXVI:    626,    1906. 
(Washington  Camp,   Ariz.)     27.  Kemp,    Econ.    Geol.,    II:     1,    1907. 
(Limestone    contacts.)      28.    Kemp,   Min.  and  Sci.   Pr.,  XCII:    220, 
1906.      (Garnet  zones.)     29.   Klockmann,  Zeitschr.  prak.  Geol.,  XII: 
73,  1904.     30.  Lawson,  Univ.  Calif.  Pub'ns,  Geology,  VIII:  219,  1914. 
(Meteoric  waters  as  agents  in  contact  met'm.)     31.  Leith,  Amer.  Inst. 
Min.  Engrs.,  Trans.,  XLVIII:    209,   1915,  and  Econ.  Geol.,  IX:    292, 
1914.     (Limestone  crystallization  at  igneous  contacts.)     32.  Lindgren, 
Amer.  Inst.  Min.   Engrs.,  XXXI:  226,   1902;   also  U.  S.  Geol.  Surv., 
Prof.   Pap.  43,  1905.      33.  Lindgren,  Ibid.,  XLVIII:    201,  1915;    also 
Econ.  Geol.,  IX:    283,  1914.     34.  Prescott,  Econ.  Geol.,  X:  55,  1915. 
35.  Stutzer,  Zeitschr.  prak.  Geol.,  XVII:    145,  1909.     36.  Uglow,  Econ. 
Geol.,  VIII:   19,   and  215,  1913.      (Emphasizes  segn.  of    elements  in 
rock.)     Discussions  by  Stewart  and  Kemp,  Econ.  Geol.,  VIII:  500  and 
597,  1913. 


498  ECONOMIC   GEOLOGY 

EMANATIONS  (GASEOUS).  37.  Brun,  Recherches  sur  L'Exhalaison  Vol- 
canique.  Geneva  and  Paris,  1911.  38.  Chamberlin,  R.  T.,  Jour.  Geol., 
XVII:  534,  1909  and  Carnegie  Inst.  Wash.,  Pub.  106,  1908.  39.  Day 
and  Shepherd,  Geol.  Soc.  Amer.,  Bull.,  XXIV:  573,  1913.  40.  Lincoln, 
Econ.  Geol.,  II:  258,  1907. 

FAULTS.  41.  Ransome,  Econ.  Geol.,  I:  777, 1906.  42.  Reid,  Geol.  Soc.  Amer., 
Bull.,  XX:  171,  1910.  (Geometry  of  faults.)  43.  Reid,  Davis,  Law- 
son  and  Ransome,  Ibid.,  XXIV:  163,  1913.  (Report  of  Committee  on 
fault  nomenclature.)  44.  Spurr,  U.  S.  Geol.  Surv.,  Prof.  Pap.  42:  144, 

1905.  (Tonopah.)     45.  Tolman,    Econ.    Geol.,    II:     506,    1907.     46. 
Tolman,  Min.  and  Sci.  Pr.,  CII:  810  and  CIII:   128,  1911.     (Graphical 
solution  of  fault  problems.) 

GANGUE  MINERALS.  See  this  topic  in  text  books  cited  on  p.  497,  also  follow- 
ing papers.  47.  Catlett,  Amer.  Inst.  Min.  Engrs.,  XXXVIII:  358, 
1908.  (Barite  in  Cuban  iron  ores.)  48.  Lindgren,  Econ.  Geol.,  I:  163, 

1906.  (Albite  in  Bendigo  veins.)     49.  Lindgren,  Amer.  Jour.  Sc.i,  V: 
418,  1898.     (Orthoclase  in  fissure  veins.)     50.  Lindgren,  Econ.  Geol., 
V:   522,  1910.     (Anhydrite.)     51.  Rogers,  Econ.  Geol.,  VI:   790,  1911. 
(Orthoclase    bearing   veins.) 

MAGMATIC  DIFFERENTIATION.  52.  Garrison,  Min.  and  Sci.  Pr.,  XCVIII: 
45,  1909.  53.  Gregory,  Smithson,  Inst.,  Ann.  Rept.,  1908:  311.  (Ig- 
neous ore.)  54.  Read,  Econ.  Geol.,  I:  111,  1906.  (Phase  rule  and  ig- 
%  neous  magma.)  55.  Spurr,  Amer.  Inst.  Min.  Engrs.,  XXXIII:  288, 
1903.  (Magmatic  segregation.)  56.  Spurr,  Econ.  Geol.,  II:  178,  1907. 
57.  Stutzer,  Iron  and  Steel  Inst.,  Jour.,  LXXIV:  106,  1907.  (Lap- 
land.) 58.  Vogt,  Zeitschr.  prak.  Geol.,  I:  4,  125  and  237,  1893.  59. 
Vogt,  Amer.  Inst.  Min.  Engrs.,  XXXI:  125,  1902.  (Problems  in  Geol- 
ogy of  Ore  Deposits.)  60.  Watson  and  Taber,  Va.  Geol.  Surv.,  Bull. 
II1-A.,  1913.  (Rutile  deposits.)  See  also  references  2,  13,  21,  p.  497. 

METALLOGENETIC  EPOCHS  AND  PROVINCES.  61.  Finlayson,  Quart.  Jour. 
Geol.  Soc.,  LXVI:  281,  1910.  (Metallogeny  British  Isles.)  62.  de 
Launay,  Traite"  de  Metallogenie.  Paris,  1913.  63.  de  Launay,  Ann. 
Mines,  10th  ser.,  XV:  220  and  303,  1909.  (Metallogeny  Asiatic  Russia.) 
64.  de  Launay,  Internat.  Geol.  Cong.,  10th  session,  1906.  (Metal- 
logeny Italy.)  65.  Lindgren,  Econ.  Geol.,  IV:  409,  1909  and  Can.  Min. 
Inst.  XII.  (Metallogenetic  epochs,  U.  S.)  66.  Miller  and  Knight,  Ont. 
Bur.  Mines,  XXIV,  Pt.  I:  243,  1915.  (Pre-Camb.  epochs  Ontario.) 
67.  Spurr,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXIII:  328,  1903,  and  U.  S. 
Geol.  Surv.,  Prof.  Pap.,  42:  276,  1905.  (Metalliferous  provinces.) 

METALLOGRAPHY.     68.  See  Refs.  3  and  14,  p.  497. 

METAMORPHISM.  69.  Clarke,  U.  S.  Geol.  Surv.,  Bull.,  616:  1916.  70. 
Leith  and  Mead,  Metamorphic  Geology.  New  York,  1915.  71.  Van 
Hise,  U.  S.  Geol.  Surv.,  Mon.,  XL VII,  1904.  (Treatise  on  Metamorph- 
ism.) 

ORE  DEPOSITION. — 72.  Bams,  Amer.  Inst.  Min.  Engrs.,  XIII:  417,  1885. 
(Electrical  activity  in  ore  bodies.)  73.  Butler,  Econ.  Geol.,  X:  101, 
1915.  (Rel'n  ore  deposits  to  different  intrusive  types.)  74.  Emmons, 
S.  F.,  Min.  and  Sci.  Pr.,  C:  739,  1910.  (Former  theories  ore  deposition.) 
75.  Emmons,  S.  F.,  Geol.  Soc.  Amer.,  Bull.,  XV:  1,  1904.  (Ore  dep'n 


ORE  DEPOSITS  499 

theories.)  76.  Emmons,  W.  H.,  Econ.  Geol.,  Ill:  611,  1908.  (Mineral 
class'n  according  to  depositional  conditions.)  77.  Fox,  Amer.  Jour. 
Sci.,  XXXVII:  199,  1839.  (Vein  form'n  by  galvanic  agencies.)  78. 
Gillette,  Amer.  Inst.  Min.  Engrs.,  XXXIV:  710,  1903.  (Osmosis  theory.) 
79.  Hatscheck  and  Simon,  Inst.  Min.  and  Met.,  Trans.,  XXI:  451,  1912. 
(Gels  in  rePn  to  ore  dep'n.)  80.  Kemp,  Amer.  Inst.  Min.  Engrs.,  Trans., 
XXXIII:  699,  1903.  (Rel'n  igneous  rocks  to  ore  dep'n.)  81.  Kohler, 
Zeitschr.  prak.  Geol.,  XI :  49, 1903.  (Adsorption  as  factor  in  ore  form'n.) 
82.  Krusch,  Min.  and  Sci.  Pr.,  CVII:  418, 1913.  (Gels.)  83.  Lindgren, 
Econ.  Geol.,  II:  105,  1907.  (Phys.  cond'ns  ore  dep'n.)  84.  Posepny, 
Amer.  Inst.  Min.  Engrs.,  Trans.,  XXIII:  197,  1894.  (Genesis  of  ore 
deposits.)  85.  Spurr,  Econ.  Geol.,  VII:  485,  1912.  (Theory  of  ore 
deposition.)  86.  Sullivan,  Econ.  Geol.,  I:  67,  1906^-and  U.  S.  Gcol. 
Surv.,  Bull.  312.  r87.  Sullivan,  Econ.  Geol.,  Ill:  750,  1908.  (Precipi- 
tation by  nitration.)  88.  Van  Hise,  Amer.  Inst.  Min.  Engrs.,  Trans., 
XXX:  27,  1901.  (Deposition  of  ores.)  89.  Weed,  Eng.  and  Min. 
Jour.,  LXXIX:  365,  1905.  (Adsorption.)  90.  Wells,  Econ.  Geol., 
V:  1,  1910,  and  U.  S.  Geol.  Surv.,  Bull.  609,  1915.  (Fractional  precipi- 
tation of  sulphides.)  91.  Wells,  Econ.  Geol.,  VIII:  571,  1913  and  U.  S. 
Geol.  Surv.,  Bull.  548,  1914.  (Electrochemical  activity.) 

ORE  SHOOTS.  92.  Irving,  Econ.  Geol.,  Ill:  143,  1908.  (Classification.) 
For  discussion  see  Ibid.,  Ill,  pp.  224,  326,  425,  534,  637,  1908.  93. 
Lindgren,  Econ.  Geol.,  IV:  56,  1909.  94.  Penrose,  Econ.  Geol.,  V:  97, 
1910.  (Causes  of.)  95.  Pope,  Econ.  Geol.,  VI:  503,  1911.  (Mag- 
matic  differentiation  as  cause  of.)  96.  Winchell,  Econ.  Geol.,  Ill: 
425,  1908. 

OUTCROPS.  97.  Emmons,  W.  H.,  Min.  and  Sci.  Pr.,  XCIX:  751,  782,  1909. 
98.  Storms,  Min.  and  Sci.  Pr.,  CI:  537,  1911. 

REPLACEMENT.  99.  Fenner,  Sch.  M.  Quart.,  XXXI:  235,  1910.  (Rhyolite 
by  stephanite  and  chalcopyrite.)  100.  Irving,  Econ.  Geol.,  VI:  527 
and  619,  1911.  (General.)  101.  Krusch,  Zeitschr.  prak.  Geol.,  XVIII: 
165,  1910.  (Primary  and  secondary  processes  in  ore  bodies.)  102. 
Lindgren,  Econ.  Geol.,  VII:  521,  1912.  (General.)  Discussion  by 
Stevens,  Ibid.,  VIII:  397,  1913.  103.  Lindgren,  Amer.  Inst.  Min. 
Engrs.,  Trans.,  XXX:  578,  1901.  (In  fissure  veins.)  104.  Smyth, 
Amer.  Jour.  Sci.,  XIX:  277,  1905.  (Quartz  by  pyrite.)  105.  Turner, 
Econ.  Geol.,  VII:  708,  1912.  (Siliceous  rock  by  pyrite.) 

SECONDARY  SULPHIDE  ENRICHMENT.  106.  Bastin,  Econ.  Geol.,  VIII:  51, 
1913.  (Metasomatism  in  downward  sulphide  enrichment.)  107. 
Cooke,  Jour.  Geol.,  XXI,  No.  1,  1913.  (Silver  ores.)  108.  Emmons, 
S.  F.,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXX:  177,  1901.  109.  Em- 
mons, W.  H.,  Econ.  Geol.,  X:  151,  1915.  (Temp,  chalcocite  zones.) 
110.  Emmons,  W.  H.,  U.  S.  GeoL  Surv.,  Bull.  529,  1913.  (General 
treatise.)  111.  Graton  and  Murdock,  Amer.  Inst.  Min.  Engrs.,  Trans., 
XLV:  26,  1914.  (Copper  ores.)  112.  Grout,  Econ.  Geol.,  VIII:  407, 
1913.  (Reaction  cold  acid  sulphate  solutions  copper,  silver,  gold,  and 
alk.  sol'n  met.  sulphides.)  113.  Kemp.  Econ.  Geol.,  I:  11,  1906. 
(Copper  ores.)  114.  Palmer  and  Bastin,  Econ.  Geol.,  VIII:  140,  1913. 
(Metallic  minerals  as  precipitants  of  silver  and  gold.)  Discussion  by 


500  ECONOMIC   GEOLOGY 

Elley,  Ibid.,  X:  580,  1915.  115.  Ravicz,  Econ.  Geol.,  X:  368, 
1915.  (Silver  ore  experiments.)  116.  Ransome,  Econ.  Geol.,  V:  205, 
1910.  (Criteria.)  117.  Rogers,  Min.  and  Sci.  Pr.,  CIX:  680.  1914. 
118.  Sales  and  Gregory,  Econ.  Geol.,  V:  678,  1910.  (Criteria.)  119. 
Spencer,  Econ.  Geol.,  VIII,  No.  7,  1913.  (Chalcocite  enrich' t.)  120. 
Tolman,  Min.  and  Sci.  Pr.,  CVI:  38,  141  and  178,  1913.  121.  Tolman, 
Amer.  Inst.  Min.  Engrs.,  Bull.,  Feb.  1916.  (Chalcocite  enrichment  and 
references.)  122.  Weed,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXX:  424, 
1901.  (Gold  and  silver.) 

VEINS,  ORIGIN,  STRUCTURE,  ETC.  123.  Bancroft,  Amer.  Inst.  Min.  Engrs., 
Trans.,  XXXVIII:  245,  1908:  and  XL:  809,  1910.  (Formation  and 
enrichment.)  124.  Beck,  Zeitschr.  prak.  Geol.,  XIV:  71,  1906;  and 
Geol.  Mag.,  Dec.  v,  III,  No.  1,  1906.  (Relation  between  ore  veins  and 
pegmatites.)  125.  Emmons,  S.  F.,  Col.  Sci.  Soc.,  Proc.,  II:  189,  1885. 
(Origin  of  fissure  veins.)  126.  Emmons,  W.  H.,  Econ.  Geol.,  IV:  755, 
1909.  (Segregated  veins.)  127.  Glenn,  Amer.  Inst.  Min.  Engrs., 
XXV:  499,  1896.  (Fissure  walls.)  128.  Kemp,  Econ.  Geol.,  VIII: 
543,  1913.  (Artificial  vein  form'n.)  129.  Kemp,  Econ.  Geol.  I:  207, 
1906.  (Problem  of  metalliferous  veins.)  130.  Kemp,  Amer.  Inst. 
Min.  Engrs.,  XXXI:  169,  1901.  (Igneous  rock  and  vein  formation.) 
*131.  Kemp,  Sch.  of  M.  Quart.,  XIII:  20,  1892.  (FillingJJ  132.  Rick- 
ard,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXXI:  198,  1902.  (Bonanzas  in 
gold  veins.)  133.  Rickard,  Ibid.,  XXVI:  193,  1897.  (Vein  walls.) 
134.  Stevens,  Ibid.,  XL:  475,  1909.  (Law  of  fissures.)  135.  Weed, 
Eng.  and  Min.  Jour.,  LXXXIII:  1145,  1907.  (Displacement  by  inter- 
secting fissures.)  136.  Weed,  Ibid.,  LXXIV:  545,  1903.  (Enrich' t  by 
ascending  alkaline  waters.)  137.  Weed,  Amer.  Inst.  Min.  Engrs., 
XXXIII:  747,  1903.  (Enrich' t  by  ascending  hot  waters.)  138.  Weed, 
Ibid.,  XXXI:  634,  1902.  (Effect  of  wall  rock.) 

WATERS,  MINE,  SPRING  AND  UNDERGROUND.  139.  Delkeskamp,  Zeitschr. 
prak.  Geol.,  XVI:  401,  1908.  (Mineral  Springs.)  140.  Emmons  and 
Harrington,  Econ.  Geol.,  VIII:  653,  1913.  (Comparison  of  mine  and 
hot  spring  waters.)  141.  Emmons  and  Larsen,  Econ.  Geol.,  VIII: 
235,  1913.  (Wagon  Wheel  Gap,  Colo.)  142.  Gautier,  Ann.  Min. 
6  ser.,  IX:  316,  1906.  Translated  Econ.  Geol.,  I:  688,  1906.  (Ther- 
mal waters  and  relation  to  vulcanism.)  143.  FincK  Proc.  Colo.  Sci.  Soc., 
VII:  193,  1904.  (Underground  water  and  ore  vp'n.)  144.  Hague, 
Geol.  Soc.  Amer.,  Bull.,  XXII:  103,  1911.  (Yellowstone  Park  waters.) 
145.  Hastings,  Amer.  Inst.  Min.  Engrs.,  Bull.,  Feb.  1908.  (Volcanic 
waters.)  146.  Hodge,  Econ.  Geol.,  X:  123,  1915.  (Mine  waters  in 
sulphides.)  147.  Kemp,  Amer.  Inst.  Min.  Engrs.,  Trans.  (Ground 
waters.)  148.  Lane,  Eng.  and  Min.  Jour.,  XII:  1909.  (Mine  waters.) 
149.  Lindgren,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXXVI:  27,  1905. 
(Steamboat  Springs,  Nev.)  150.  Lindgren,  Econ.  Geol.,  V:  22,  1910. 
(Ojo  Caliente.)  151.  Mendenhall,  Ibid.,  IV:  35,  1909.  (Ground water.) 
152.  Tolman,  Min.  and  Sci.  Pr.,  Mar.  16,  1912.  (Magmatic  origin  of 
ore  solutions.)  153.  Weed,  U.  S.  Geol.  Surv.,  Bull.  260,  1905.  (Hot 
spring  deposits.)  154.  Weed,  U.  S.  Geol.  Surv.,  21st  Ann.  Rept.,  II: 
227,  1900. 


ORE   DEPOSITS  501 

WEATHERING.  155.  Buehler  and  Gottschalk,  Econ.  Geol.,  V:  28,  1910. 
(Experimental  ox'n  of  sulphides.)  Also  Ibid.,  VII:  15,  1912.  156. 
Penrose,  Jour.  Geol.,  II:  288,  1894.  (Weathering  ore  deposits.)  157. 
Steidtman,  Econ.  Geol.,  Ill:  381,  1908.  (Graphic  comparison  of  alter- 
ation by  weathering  and  hot  solutions.)  158.  Winchell,  Econ.  Geol., 
II:  290,  1907.  (Ox'n  of  pyrite.)  The  best  general  discussions  are  in 
textbooks.  See  also  Ref.  110,  120. 

MISCELLANEOUS  TOPICS.  159.  Apgar,  Amer.  Inst.  Min.  Engrs.,  Trans., 
XLVII:  65,  1914.  (Use  of  microscope  in  mining  engineering.)  160. 
Becker  and  Day,  Wash.  Acad.  Sci.,  Proc.,  VII:  283,  1905.  (Linear 
force  of  growing  crystals.)  161.  Emmons,  S.  F.,  Amer.  Inst.  Min. 
Engrs.,  Trans.,  XXII:  53,  1894.  (Geol.  distrib'n  useful  metals.)  162. 
Emmons,  S.  F.,  Ibid.,  XVI:  804,  1888.  (Struct  rel'ns  of  ore  deposits.) 
163.  Emmons,  S.  F.,  Min.  and  Sci.  Pr.,  Sep.  22,  1906.  (Forms  of  ore 
deposits.)  164.  Hastings,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXXIX: 
104,  1909.  (Origin  pegmatites.)  165.  Irving,  Smith  and  Ferguson, 
Ore  Deposits,  pub'd  by  Amer.  Inst.  Min.  Engrs.,  1913.  (Many  mis- 
cellaneous references.)  166.  Kemp,  Can.  Min.  Inst.,  XII:  356,  1910; 
Min.  and  Sci.  Pr.,  Mar.  20,  1909.  (What  is  an  ore.)  167.  Lindgren, 
Econ.  Geol.,  I:  34,  1906.  (Ore  dep'n.  and  deep  mining.)  168.  Rick- 
ard,  Inst.  Min.  and  Met.,  Bull.  122,  Nov.  12,  1914.  (Persistence  of  ore 
in  depth.)  169.  Rogers,  Econ.  Geol.,  VII:  638,  1912.  (Paragenesis.) 
170.  Stevens,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XLVII:  91,  1914. 
(Laws  of  jointing.)  171.  Vogt,  Zeitschr.  prak.  Geol.,  VI:  225,  314,  377 
and  413,  1898;  VII:  10,  1899.  (Distribution  of  elements  and  conc'n 
of  metals  in  ore  bodies.)  172.  W7agoner,  Amer.  Inst.  Min.  Engrs., 
Trans.,  XXXI:  798,  1902.  (Gold  and  silver  in  sedimentary  rocks.) 
173.  Washington,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXXIX:  735,  1909. 
(Distrib'n  of  elements  in  igneous  rocks.)  174.  Wells,  Econ.  Geol.,  VI: 
211,  1911.  (Hydrolysis  in  geological  chemistry.)  175.  Wright  and 
Larsen,  Amer.  Jour.  Sci.,  4th  ser.,  XXVII:  421,  1909.  (Quartz  as 
geologic  thermometer.) 


CHAPTER    XV 


IRON    ORES 

IRON  is  an  abundant  constituent  of  the  earth's  crust,  and  yet  few 
minerals  are  capable  of  serving  as  ores  of  this  metal,  because  they 
do  not  contain  it  in  the  right  combination  or  in  sufficient  quantity 
to  make  its  extraction  possible  or  profitable. 

The  iron  ores  having  the  greatest  commercial  value  at  the  present 
day  are  usually  those  which  are  favorably  located,  of  high  quality, 
in  considerable  quantity,  and  possessing  a  structure  such  as  to  render 
their  extraction  easy.  These  four  requirements  have  been  met  to 
such  an  eminent  degree  by  the  deposits  located  in  the  Lake  Superior 
district  that  they  now  form  the  main  source  of  supply  for  furnaces 
in  the  eastern  and  central  states,  and  many  of  the  iron  mines  in 
the  eastern  part  of  the  United  States  have  found  it  difficult  to  com- 
pete with  them,  although  it  is  true  that  a  number  of  deposits  are 
worked  to  supply  local  demand,  owing  to  their  proximity  to  furnace, 
flux,  and  coal,  or  because  they  possess  certain  desirable  character- 
istics. 

Iron-ore  Minerals.  —  The  ore  minerals  of  iron,  together  with 
their  composition  and  theoretic  percentage  of  metallic  iron,  are':  — 


MAGNETITE.     Magnetic  iron  ore,  Fe3O4    .         .         .         . 
HEMATITE.        Specular  iron  ore,  red  hematite,  fossil  ore,  Clinton 

ore,  Fe2O3 

LiMONiTE.1       Brown  hematite,  bog  iron  ore,  ochre,  brown  ore 

2Fe2O3,  3H2O 

SIDERITE.          Spathic  ore,  blackband,  clay-iron  stone,  kidney 

ore,  FeCO3 

Of  subordinate  value:  — 

PYRITE.  FeS2 

FRANKLINITE.    (Fe,  Zn,  Mn)0,  (Fe,  Mn)203     .... 
PYRRHOTITE.     Chiefly  FeS 


72.4% 

70% 

59.89% 

48.27% 

46.6% 
±44.1% 
±61.6% 


Magnetite  is  black,  often  granular  with  a  metallic  luster.     It  has  a  black 
streak,  hardness  of  5.5-6.5,  specific  gravity  of  5.5-6.5,  and  is  strongly  magnetic. 

1  The  group  name   "  brown  ore  "   is  sometimes  used  to  include  several  hydrous 
oxides,  such  as  limonite,  turgite,  and  gothite. 

502 


IRON   ORES  503 

Some  occurrences  may  run  high  in  titanium,  especially  those  found  in  basic 
igneous  rocks.  Hematite  is  red  to  brownish  red,  steel-gray,  or  even  black. 
It  is  commonly  fine-grained,  but  the  specular  varieties  may  be  quite  coarse. 
It  ranges  from  massive  to  powdery,  and  has  a  specific  gravity  of  5.2.  Limonite 
is  never  crystalline,  and  varies  widely  in  appearance;  some  forms  are  powdery, 
others  massive,  and  these  may  be  porous,  vesicular,  stalactitic,  or  even, 
though  rarely,  solid.  The  specific  gravity  is  3.8.  The  color  is  brown  to 
brownish  yellow  on  the  fracture,  but  may  be  black  and  shiny  on  the  natural 
surface.  Gothite  (Fe2O3,  H2O)  and  other  hydrous  oxides  with  less  water  than 
limonite  are  sometimes  associated  with  it.  Indeed  much  of  the  commercial 
limonite  or  brown  ore  is  an  intimate  mixture  of  several  of  the  hydrous  oxides  of 
iron.  Siderite,  when  occurring  in  commercial  quantities,  is  rarely  in  cleavable 
form,  but  occurs  as  a  fine-grained  mass,  with  impurities.  Hematite  is  by 
far  the  most  valuable  of  the  iron-ore  minerals,  chiefly  on  account  of  its  easier 
reduction,  but  also  because  of  the  greater  richness  of  the  known  important 
deposits. 

The  deficiency  in  iron  content  shown  by  many  ores  is  due  to  the 
presence  of  common  rock-forming  minerals  in  t,he  gangue,  the  im- 
purities which  they  supply  being  alumina,  lime,  magnesia,  silica, 
and  also  metallic  minerals  which  have  titanium,  arsenic,  copper, 
phosphorus,  and  sulphur.  The  effect  of  the  last  four  is  in  general 
to  weaken  the  iron. 

Silica  is  objectionable  because  it  displaces  iron,  and  because  just  ^o  much 
lime  is  required  to  flux  it,  but  some  furnaces  turn  out  iron  for  foundry  pur- 
poses containing  10  or  more  per  cent.  Ores  carrying  as  high  as  40  per  cent 
SiO2  are  used  in  small  quantities.  Lime  in  small  amounts  does  no  harm, 
but  in  large  quantities  needs  to  be  fluxed  off.  It  is  not  present  in  any  quan- 
tity in  limonite,  but  may  run  high  in  the  Clinton  red  ores.  Alumina  m?  /•. 
run  somewhat  high  in  limonites,  because  of  admixed  clay.  Pyrite  is  the 
common  source  of  the  sulphur,  but  in  some  limonites  it  may  come  from 
gypsum  or  barite.  Titanium,  a  common  ingredient,  is  found  in  some  quantity 
in  many  magnetite  deposits  (see  Titaniferous  magnetites,  also  refs.  28,  30,  33a) 
and  up  to  the  present  time  has  rendered  them  practically  useless,  not  because 
it  interferes  with  the  quality  of  the  iron,  but  because  it  makes  the  ore  highly 
refractory,  and  drives  much  of  the  iron  into  the  slag.  Experiments  have  been 
made  looking  towards  the  utilization  of  these  titaniferous  magnetites  for  the 
manufacture  of  ferrotitanium;  indeed  these  have  been  used  for  several  years 
in  the  manufacture  of  this  alloy,  for  although  rutile  is  preferred  it  is  too 
expensive.  Manganese,  when  present,  is  found  mostly  in  the  limonite  ores 
and  for  certain  purposes  is  desirable.  It  is  also  prominent  in  some  of  the 
Lake  Superior  ores.  Apatite  yields  the  phosphorus.  As  this  cannot  he 
eliminated  in  either  the  blast  furnace  or  the  acid  converter  used  in  making 
Bessemer  steel,  and  as  the  allowable  limit  of  phosphorus  in  pig  iron  used  for 
this  purpose  is  ^.  per  cent,  a  distinction  is  usually  made  between  Bessemer 
and  non-Bessemer  ores,  the  maximum  amount  of  phosphorus  permissible  in 
iron  ore  to  be  used  for  this  purpose  being  TSTTO  of  the  percentage  of  metallic 


504  ECONOMIC   GEOLOGY 

iron  contents  of  the  ore.     The  phosphorus  contents  of  many  high-grade  ores 
falls  considerably  below  the  allowable  limit. 

Classification. — Iron-ore  deposits  have  originated  in  a  number 
of  different  ways,  including:  1.  Magmatic  segregation  deposits 
(Lake  Sanford,  New  York,  etc.)  2.  Contact-metamorphic  de- 
posits (Iron  Springs,  Utah;  etc.).  3.  Sedimentary  ores  (bedded 
hematite  and  limonite,  bog  ores,  etc.).  4.  Ores  concentrated  by 
meteoric  waters,  and  deposited  as  replacements  (some  Lake 
Superior  hematites,  Oriskany  limonites),  or  in  residual  materials 
(Virginia  Cambro-Silurian  limonites).  5.  Lenticular  masses  in 
metamorphic  rocks,  of  variable  origin  (some  magnetite  and  pyrite 
deposits).  6.  Gossan  ores  (limonite  capping  of  many  sulphide 
ore  bodies).  7.  Replacements  by  ascending  waters;  and  8. 
Placer  deposits  (magnetite  sands). 

Iron-ore  bodies  may  show  a  variety  of  form,  but  many  of  the 
important  deposits  known  in  this  country  are  lens-  or  basin-shaped 
in  outline.  Irregular  masses  and  beds  are  not  uncommon. 

Iron  ores  show  a  wide  geologic  distribution,  those  found  in  the 
United  States  for  example  ranging  from  pre-Cambrian  to  Recent. 
The  occurrences  of  the  different  kinds  of  ore  are  best  discussed 
separately,  and  for  practical  as  well  as  for  other  purposes  a 
mineralogic  and  geographic  grouping  seems  better  in  this  case 
than  a  genetic  one. 

MAGNETITE 

United  States. — Magnetite  occurs  (Fig.  153)  (1)  as  lenticular 
masses  commonly  in  metamorphic  rocks;  (2)  as  more  or  less  lens- 
shaped  and  tabular  bodies  in  igneous  rocks;  (3)  as  sands  on  the 
shores  of  lakes  and  seas;  (4)  as  contact-metamorphic  deposits; 
(5)  as  replacements  in  limestone,  not  of  contact-metamorphic 
character;  (6)  as  veins,  and  (7)  in  residual  clays. 

The  first  class  includes  the  most  important  deposits  now  worked 
in  this  country.  The  second  1  and  third  groups  run  too  high  in 
titanium  to  have  any  commercial  value  at  the  present  time,  but 
the  second  may  become  of  importance  in  the  future,  and  more- 
over some  of  its  representatives  are  of  large  size.  Examples  of 
the  fourth  class  are  known  at  a  number  of  points  in  the  West, 
and  while  few  of  them  are  worked,  they  may  some  day  become 
of  great  importance.  They  carry  hematite  in  addition  to  mag- 
netite. The  fifth,  sixth,  and  seventh  groups  are  unimportant. 

1  This  is  not  true  of  all  the  European  deposits,  see  p.  517. 


IRON   ORES 


505 


Distribution  of  Magnetites  in  the  United  States  1  (Fig.  153). 
Non-Titaniferous  Magnetites.  —  These  are  usually  found  in  the 
form  of  lenticular  deposits  in  metamorphic  rocks.  The  most 
important  series  of  occurrences  lies  in  the  crystalline  belt  of  rocks 
extending  from  New  York  into  Alabama,  deposits  being  known  in 
New  York,  New  Jersey,  Pennsylvania,  Virginia,  and  North  Caro- 
lina. 


FIG.  153.  —  Map  showing  distribution  of  hematite  and  magnetite  deposits  in  the 
United  States.     (After  Harder,  U.  S.  Geol.  Surv.,  Min.  Res.,  1907.) 

The  lenses,  which  are  interbedded  with  gneisses  of  either  acid  or 
basic  character  and  often  conform  with  the  latter  in  dip  and  strike, 
are  of  variable  size,  and  may  occur  either  singly  or  in  series,  the  ore 
body  commonly  showing  pinching  and  swelling,  or  even  faulting. 
Well-defined  boundaries  are  sometimes  wanting.  Feldspar,  horn- 
blende, and  quartz  are  common  gangue  minerals,  while  apatite  is 
prominent  in  some.  Although  the  ore  as  mined  is  frequently  of 
sufficient  purity  to  be  shipped  direct  to  the  blast  furnace,  in  some 
instances  it  is  so  lean  as  to  require  concentration  by  magnetic 
methods.  A  description  of  one  or  two  occurrences  will  serve  as  types : 

Adirondack  Region,  New  York  (27,  30)  —  The  rocks  of  the  Adiron- 
dack region  (Fig.  154)  are  almost  exclusively  of  pre-Cambrian  age, 
with  occasional  inliers  of  the  bordering  Paleozoic  strata,  whose  basal 

1  Magnetites  in  general  fall  into  two  classes  on  basis  of  titanium  content,  viz. 
the  non-titaniferous  and  titaniferous. 


506 


ECONOMIC  GEOLOGY 


Sediments 
i  ...  .. Granite  Sjcnite 
Kv>1l  ^a  Acidic  Gneiss 

gggAnorthosite.Gabbre    * 
Grenville.Senes 

•+•  Hematite  DepositB  cj 

OTltaniferous  Magnetites 


FIG.  154.  —  Geologic  map  of  Adirondack  Region,  New  York,  showing  location  of 
iron-ore  deposits.     (After  NGwland,  Econ,  Geol.,  II.) 

member,  the  Potsdam  sandstone,  rests  unconformably  on  the  older 
crystallines.  The  latter  have  in  most  cases  been  subjected  to  power- 
ful compression,  and  sometimes  greatly  changed  by  metamorphism, 
in  fact  so  much  so  that  their  original  character  is  determinabte  with 
difficulty. 

The  following  members  are  recognized,  beginning  with  the  oldest: 
I.  Metamorphic  rocks.  —  1 .  Sedimentary  or  Grenville  Series.  These 
consist  of  limestones  and  dolomites,  often  impregnated  with  pyrite, 
graphite,  and  silicates,  and  by  an  increase  in  the  latter  may  pass 
into  schists.  Both  rock  types  occur  in  long  narrow  belts,  bounded 
by  sedimentary  gneisses.  2.  Gneisses  of  acid  to  basic  character,  often 
showing  garnet,  sillimanite,  graphite,  cyanite,  pyrite,  etc.  3.  Am- 
phibolites,  composed  mainly  of  hornblende  and  feldspar,  and  which 
may  be  metamorphosed  dikes  or  magnesian  shale.  4.  Quartzites  of 
infrequent  occurrence.  5.  Gneisses  of  doubtful  relationships. 


IRON   ORES 


507 


II.  Igneous  Rocks. — These  include:  (1)  anorthosite  (the  earliest), 
gabbro,  syenite,  and  granite,  all  connected  by  intermediate  rock 
types  and  probably  representing  derivations  from  the  same  magma. 
(2)  Dikes,  mostly  diabases. 

Ores.— The  non-titaniferous  magnetites  are  the  most  widespread 
of  the  Adirondack  ores,  and  occur  on  both  the  eastern  and  western 
sides  of  the  mountains. 


MAP  OF  THE 
,  CHAMPLAIN  &  MORIAH 

RAILROAD 

Scale.!  inch = 1^  miles 

Datum  is  Sea  Level;  the  contour  interval  is  100  ft 


FIG.  155.  —  Map  of  Mineville,  N.  Y.,  iron-ore  district.     (After  Graribery,  Eng.  and 
Min.  Jour.,  LXXXL) 

The  ores  vary  from  impure  lean  varieties,  consisting  of  magnetite 
mixed  with  the  country-rock  minerals  (i.e.  quartz,  feldspar,  pyrox- 
ene, hornblende,  etc.),  to  pure  magnetite.  The  richest  ore  aver- 
ages 60  to  70  per  cent  iron,  and  comes  chiefly  from  Mineville,  while 
those  ores  carrying  under  50  per  cent  have  to  be  concentrated. 
The  phosphorus  content  is  variable,  but  seems  to  be  lower  in  the 
leaner  ones,  while  in  the  non-Bessemer  ores  it  may  exceed  2  per 
cent.  The  amount  of  sulphur  is  also  changeable,  but  is  highest 
in  those  ore  bodies  found  in  the  Grenville  gneiss. 


508  ECONOMIC   GEOLOGY 

While  the  ore  bodies  are  variable  in  shape  they  show  in  general  a 
somewhat  lenticular  cross-section,  with  the  tabulation  extending 
parallel  with  the  strike;  but  regularity  is  more  common  on  the 
north  and  west  sides  of  the  province,  for  in  the  eastern  districts 
there  is  the  greatest  irregularity  due  to  a  complexity  of  pinches, 
swells,  and  compressed  folds.  The  wall  rocks  include  gneisses 
of  granitic,  syenitic,  and  dioritic  composition,  as  well  as  schists 
and  occasionally  limestones. 

Minevitte,  New  York  (30). — The  ore  bodies  at  this  locality  are 
the  largest  and  most  productive  in  New  York  State  at  the  present 
time. 

They  are  of  lenticular  character,  but  in  some  cases  the  lenses 


FIG.    156.  —  Thin   section   of  magnetite   gneiss,  Lyon    Mountain,  N.  Y.     Mag- 
netite (black);    feldspar  (gray);    pyroxene  (crossed  cleavage).    X30. 

are  so  flat  and  of  such  extent  as  to  be  commonly  spoken  of  as  beds; 

moreover,  some  of  them  have  been  bent  over  into  a  southwesterly 

pitching  fold,  whose  crest  has  been  stretched  and  pinched,  while 

faulting  at  the  northern  end  of  this  has  complicated  the  structure. 
The  ores  occur  as  integral  members  of  the  syenite  series,  and  are 

in  the  form  of  layers  conformable  to  the  banding  or  foliation  of 

the  inclosing  rocks. 

There  are  at  least  three  large  ore  bodies  (Fig.  157),  viz.  :— 

1.  The  Barton  Hill  ore  body,  forming  a  practically  continuous 

bed,  whose  outcrop  is  approximately  3500  feet  long  in  a  direction 


PLATE  XLIII 


FIG.  1.  —  View  of  open  cut  in  magnetite  deposit,  Mineville,  N.  Y.  The  pillars  are 
left  to  support  the  gneiss  hanging  wall.  (After  Witherbee,  Iron  Age,  Dec.  17, 
1903.) 


FIG.  2.  —  General  view  of  magnetic  separating  plants  and  shaft  houses,  Mineville, 
N.  Y.     (After  Witherbee,  Iron  Age,  1903.) 


(509) 


510 


ECONOMIC   GEOLOGY 


a  little  east   of  north.     Iron   content,   30-35   per  cent;    concen- 
trates, 65  per  cent;    Fe,  .025  per  cent  P. 


la            sV       .«« 

.23                 o2          §J 

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Datum                                                                                            1 

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Datum            -4^'M'^^^^                       \ 

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—  ri    i    I    i    1    ,  T1*'8*!    —  ^ 

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Datum^ 

Longitudinal  Section-21"Mine  to"E"Shaft 
GEOLOGICAL  CROSS-SECTION 

TO  ACCOMPANY 

MAP  OF  THE  MINEVILLE  AREA 

EXPLANATION 

Drift             Gneiss          Gabbro        Trap  Dike     Ore  Velna 
Datum  is  level  of  Lake  Champlain 

FIG.  157.  —  Sections  of  the  old,  "  21  "-Bonanza-Joker  ore  beds,  Mineville,  N.  Y. 
(After  Granbery,  Eng.  and  Min.  Jour.,  LXXXI.) 


2.  The  Harmony  bed,    ying  to  the  southwestward  of  Barton 
Hill,  and  striking  northwest,  with  a  rather  flat  southwest  dip. 


IRON   ORES  511 

It  is   10  to  20  feet  thick  and  cut  by  several  narrow  trap  dikes 
which  occupy  fault  planes  of  10  to  50  feet  displacement. 

3.  A  large  ore  body  which  appears  to  be  made  up  of  three  principal 
and  separated  parts,  known  as  the  Miller,  the  Old  Bed  or  Mine  23, ; 
and  the  "  21' '-Bonanza-Joker.  This  is  the  chief  source  of  the  ore. 
There  is  some  doubt  whether  there  is  any  connection  between  the 
Joker  and  the  Harmony.  This  Old  Bed  group  extends  in  a  prac- 
tically unbroken  stretch  for  about  a  half  mile,  exhibiting  at  the  same 
time  a  most  complex  fold,  referred  to  above. 

The  ores  are  granular  masses  of  magnetite  which  in  the  Barton 
Hill  group  were  prevailingly  of  Bessemer  grade,  but  which  in  the  Old 
Bed  series  are  high  in  phosphorus. 

The  lean  ores  are  mixed  with  the  minerals  of  the  wall  rocks,  and 
among  these  the  basic  syenite  is  the  chief  one. 

At  Lyon  Mountain  (30)  the  ore  is  a  lean  magnetite  traceable  for  6  miles 
and  from  20  to  200  feet  wide,  and  occurs  in  a  rock  intermediate  between 
granite  and  syenite.  Most  of  the  ore  is  low  in  phosphorus,  the  concen- 
trates carrying  about  .008  per  cent  P  and  65  per  cent  Fe. 

New  Jersey.  —  In  northern  New  Jersey,  the  magnetite  deposits  form 
layers  or  bands  in  the  Franklin  (pre-Cambrian)  limestone,  or  as  flat  lenses 
in  the  associated  gneisses. 

The  ore  according  to  Bayley  (24a)  consists  mainly  of  magnetite,  horn- 
blende, pyroxene,  and  apatite,  sometimes  intimately  mixed.  Pyrite  and 
quartz  are  not  uncommon,  and  all  the  associated  minerals  occur  in  the 
country  gneiss. 

The  ore  bodies,  which  are  lens-shaped,  lie  with  their  longer  axes  conform- 
ing to  the  foliation  of  the  gneisses,  and  the  ore  usually  grades  into  the 
gneiss,  although  sharp  boundaries  are  in  some  cases  known.  Several 
lenses  may  overlie  each  other,  and  then  the  intervening  rock  may  be  either 
gneiss,  pegmatite  full  of  magnetite,  or  coarse-grained  hornblendic  rock, 
with  ore  veinlets  paralleling  the  foliation  of  the  gneiss.  This  series  of 
magnetites  extends  northeastward  into  the  Highland  region  of  New  York. 

Origin  of  Magnetites. —The  origin  of  the  magnetites  found  in  the 
gneisses  has  formed  a  puzzling  problem  to  geologists,  whose 
correct  solution  depends  in  part  at  least  on  the  correct  interpretation 
of  the  origin  of  the  inclosing  rocks. 

If  the  gneisses  are  of  sedimentary  origin,  then  it  is  possible  that  the 
ores  may  represent  metamorphosed  deposits  of  magnetite  sands, 
limonite,  or  siderite,  and  the  parallelism  of  the  ore  bodies  with  the 
foliation  of  the  gneisses  might  be  regarded  by  some  as  evidence  in 
favor  of  such  a  view. 


512  ECONOMIC  GEOLOGY 

But  even  if  the  gneisses  were  of  sedimentary  origin,  it  might  still 
be  possible  that  the  ores  were  of  later  introduction,  as  has  been 
suggested  by  some.  Thus  Keith  held  the  view  that  the  North  Caro- 
lina magnetites  were  replacement  deposits  (26),  while  Kemp  for- 
merly advanced  the  theory  that  the  ore  bodies  at  Mineville  (27)  have 
been  formed  by  iron-bearing  magmatic  waters,  which  were  given 
off  from  the  neighboring  gabbros  and  penetrated  the  gneisses  while 
the  latter  were  probably  still  at  great  depths,  and  before  their 
metamorphism  was  complete.  The  presence  of  apatite  and  fluorite 
was  thought  to  show  that  mineralizing  vapors  also  played  a  part. 
A  similar  origin  was  suggested  by  Spencer  for  the  New  Jersey  mag- 
netites (34). 

Later  studies  by  Kemp  and  Newland  in  the  Adirondacks  (30) 
seem,  however,  to  indicate  that  the  acid  gneisses  are  probably  of 
igneous  origin,  and  that  the  magnetites  themselves  are  products 
of  magmatic  differentiation.  That  there  is  no  obstacle  to  this 
theory  is  shown  by  Newland,  who  points  out  that  the  acid  igneous 
rocks  of  the  region  contain  a  large  excess  of  iron  over  the  amounts 
combined  with  the  lime  and  magnesia  to  form  silicates.  The  pe- 
culiar form  of  some  of  the  ore  bodies  is  likewise  perhaps  only 
explainable  by  this  theory.  A  fact  not  to  be  overlooked,  however, 
is  the  occurrence  of  fluorite,  apatite,  hornblende,  etc.,  intercrystal- 
lized  with  magnetite,  or  the  frequent  association  of  the  latter  with 
pegmatite  or  vein  quartz,  a  group  of  conditions  which  are  sugges- 
tive of  mineralizing  agents,  and  their  deposition  by  pneumatolytic 
or  aqueous  action. 

Cornwall,  Pennsylvania  (35).  —  A  somewhat  unique  deposit  occurs  at 
Cornwall,  Lebanon  County,  Pennsylvania,  and  at  several  other  localities 
in  southern  Pennsylvania.  The  ore  is  found  along  the  contact  of  Triassic 
diabase,  with  Cambro-Ordovician  limestones  or  more  rarely  Triassic  shales, 
and  consists  mainly  of  magnetite,  but  carries  sufficient  pyrite  to  require 
roasting,  and  occasionally  a  little  specular  hematite.  The  ore  forms  large 
and  small  masses  of  irregular  shape,  lying  either  within  the  sediments  or 
along  the  contact,  and  while  it  appears  to  be  a  true  contact  metamorphic 
deposit,  the  contact  silicates  are  not  prominent.  The  ore  averages  about 
45  per  cent  iron,  is  low  in  phosphorus,  but  high  in  sulphur,  silica,  lime,  and 
magnesia.  It  also  carries  some  copper. 

Iron  Springs,  Utah  (29).  —  Iron  deposits  are  widely  scattered 
over  the  western  states,  but  few  have  been  worked,  owing  to  the 
limited  demand  in  that  region.  They  can  be  regarded,  however, 
as  reserves  which  may  become  of  importance  in  the  future. 
Among  the  best  known  of  these  are  those  of  the  Iron  Springs 


IRON   ORES 


513 


district   of  southwestern  Utah,  which  belongs  to  the   contact- 
met  amorphic  type. 

At  this  locality  the  series  of  sedimentary  rocks  ranges  from  Car- 
boniferous to  Pleistocene  (Fig.  158),  and  is  intruded  by  three  lacco- 
liths of  biotite  andesite,  which  have  especially  affected  the  Home- 


Late  tuffaceous  rhyolite 
(4000 


Pyroxene  andesfte  Brec\ 
cia  and  agglomerate  f. 
(100') 

Hornblende  andesite  " 
breccia  and  agglomer->- 
ate  (150')  ), 

Later  trachyte  (50')''' 


•'.  7  *  -,•  v  ^Yg^^y°  Y  Y 

i/l^v^v 


<XXXXXXXXXyx 


Pleistocene  and  Recent  ~\  J-j 

lake,  stream  and  outwash  1-2  O 

deposits  f<tf«J 

P|eistocene(?>  conglomerated  00'JQ,C 

Biotite-  hornblende-  pyroxene 
andesite  (200') 


Biotite  dacite  (300') 


Latest  trachyte     1 50'-  3007 


Early  tuffaceous  rhyolite 
(300'-  400') 


Early  trachyte     50'-  600' 


Claron  limestone,  conglomerate 
and  sandstone    (1000'?) 


Pinto  sandstone,  shale,  conglom- 
' 


erate  and 
(1,500'; 


imestooe  lenses 


Homestake  limestone  (50'-  500' 


Biotite  andesite 


Ug 

9 


FIG.  158.  —  Geologic  column  of  the  Iron    Springs,    Utah    district.      (After   Leith 
and  Harder,  U.  S.  Geol.  Surv.,  Bull.  338.) 


514 


ECONOMIC   GEOLOGY 


stake  (Carboniferous)  limestone,  and  to  a  lesser  extent  the  Claron 
(Tertiary)  limestone. 

The  ore  bodies  are  of  three  types,  viz.:  (1)  fissure  veins  in 
andesite;  (2)  fissure  and  replacement  deposits  on  the  contact  of 
the  andesite  and  Carboniferous  limestone;  and  (3)  as  breccia  cement 
in  Cretaceous  quartzite. 


METAMORPHOSED 
HOMESTAKE 
LIMESTONE 


FIG.  159. —  Map  of  a  portion  of  the  Iron  Springs,  Utah  district,  showing  occurrence 
of  iron  ore  in  limestone  near  andesite  contact,  and  also  in  the  igneous  rock. 
(After  Leith  and  Harder,  U.  S.  Geol.  Surv.,  Bull.  338.) 


The  second  of  these  is  the  most  important,  and  while  the  ore 
bodies  are  roughly  lens-shaped,  with  their  longer  diameters  parallel 
to  the  contact,  still  there  are  numerous  irregularities,  due  to  faulting 
and  Bother  causes.  The  vertical  dimensions  are  unknown,  as  the 
deepest  test  shaft  is  down  only  130  feet,  and  has  not  reached  water 
level. 

The  ore  consists  of  magnetite  and  hematite  with  a  small  amount 
of  limonite,  the  first  two,  of  course,  being  characteristic  of  contact- 
rnetamorphic  deposits.  The  ore  shows  a  hard,  crystalline  texture 
at  the  surface,  but,  as  is  sometimes  found  in  arid  regions,  becomes 
softer  with  depth.  The  gangue  is  chiefly  quartz  or  chalcedony  near 
the  surface,  but  calcite  increases  with  depth.  The  contact  minerals, 


IRON  ORES 


515 


garnet,  diopside,  apatite,  mica,  hornblende,  and  other  silicates,  are 
minor  constituents. 


500  feet 


FIG.  160.  —  Cross  section  of  Desert  Mound  contact  deposit,  Iron  Springs,  Utah 
district,  a,  iron  ore  ;  6,  laccolithic  andesite  ;  c,  Homestake  limestone  ;  d,  altered 
Homestake  limestone  ;  e,  Pinto  sandstone.  (After  Leith  and  Harder,  U.  S.  Geol. 
Surv.,  Bull.  338.) 

While  much  of  the  ore  runs  above  60  per  cent  in  iron,  the  average 
is  about  56.  Phosphorus  is  uniformly  high,  but  sulphur,  copper,  and 
titanium  are  not  in  prohibitive  amounts. 

Leith  and  Harder  believe  that  the  ores  are  closely  related  in  origin 
to  the  andesite  laccolith  intrusions,  and  suggest  the  following : 

The  contact  metamorphism  first  produced  a  zone  of  about  60 
feet  width,  containing  varying  amounts  of  albite,  kaolinite,  actin- 
olite,  diopside,  quartz,  orthoclase,  serpentine,  phlogopite,  andra- 
dite,  iron  ores,  osteolite  (earthy  apatite),  andalusite,  wollastonite, 
calcite,  etc.  -  There  is  also  glassy  material  which  appears  to  repre- 
sent fused  wall  rock.  Solutions  given  off  by  the  andesite  dis- 
solved out  the  lime  and  magnesia  carbonates,  while  the  residue 
recrystallized  to  form  silicates.  Later  the  iron  was  brought  in  from 
the  eruptive,  probably  as  ferrous  chloride,  which  reacted  with  water 
(above  500°  C.),  yielding  magnetite  and  hydrochloric  acid,  thus:  — 
3  FeCl2  +  4  H2O  =  Fe3O4  +  6  HC1  +  H2  +  77  calories. 

The,  HC1  attacked  the  limestone,  which  was  replaced  by  the  mag- 
netite. 

This  view  that  the  eruptive  contributed  but  little  material  to  the 
contact  zone  is  disputed  by  Kemp,  who,  by  taking  the' author's 
analyses  and  recasting  them,  shows  that  the  reverse  may  be  true. 
Moreover,  if  Leith's  conclusions  are  correct,  then  a  contact  zone 
60  feet  thick  must  represent  a  shrunken  residue  of  a  limestone  belt 
300  feet  thick  which,  as  pointed  out  by  Kemp,  seems  hardly 
possible. 

Other  Occurrences  (16). — Small  deposits  of  magnetite  are  found  in  the 
limestones  of  the  Shenandoah  Group  and  their  residual  clays  in  southwestern 
Virginia  (16,  23a),  The  magnetite,  which  is  associated  with  hematite  and 


516 


ECONOMIC  GEOLOGY 


siderite,  is  of  high  grade  and  low  in  phosphorus  (23a).  Magnetite  occurs 
sparingly  in  the  Marquette  Range  of  Michigan,  where  it  is  found  in  the  schists. 
Contact-metamorphic  deposits  are  found  at  a  number  of  localities  in  the 
West,  but  the  chief  occurrences  are  in  Colorado,  New  Mexico,  Utah,  and 
California.  That  at  Fierro,  N.  Mex.  (25a)  occurs  in  Paleozoic  limestone, 
near  its  contact  with  a  Tertiary  monzonite  porphyry.  Another  found  at 
Heroult,  Calif.,  lies  chiefly  at  the  contact  of  diorite  and  Triassic  limestone 
(32). 

Analyses  of  Magnetites.  —  The  following  table  gives  the  com- 
position of  non-titaniferous  magnetites  from  a  number  of  localities. 
It  is  not  possible  in  all  cases  to  obtain  analyses  of  recent  date. 

ANALYSES  OF  MAGNETITES 


I 

II 

Ill 

IV 

V 

VI 

VII 

VIII 

IX 

Fe  .     . 

60.03 

60.91 

61.69 

59.93 

56.05 

64.9 

56.00 

61.85 

1  89.4  i 

)    7.52 

SiO2 

4.48 

4.49 

18.90 

7.72 

7.76 

3.98 

7. 

4.74 

2.4 

P    ? 

1.635 

1.548 

1.305 

.08 

.036 

.021 

.2 

.112 

.011 

s    . 

.021 

.027 

1.23 

.19 

.06 

.071 

.057 

.015 

.099 

Ti   . 

.12 

.03 

1.30 

— 

— 



— 



Cu  . 

.007 

— 

— 

.005 

.027 

— 

.  — 

Moist 

.28 

.25 

— 

— 

— 

— 

3. 

2.62 

— 

Mn 



.55« 

.17 

none 

.158 

.196 

2.423 

.18* 

Al,03 

— 

— 

12.48 

.324 

1. 

.74 

CaO 





4.45 

— 

— 

1.010  > 

4. 

|  .16 



MgO 

— 

— 

.86 

— 

— 

1.131  \ 

1.95 

.3 

I.  Sample  60  carloads.  IT.  Sample  35  carloads,  21  pit,  both  Mineville,  N.  Y.,  N.  Y.  State 
Museum,  Bull.  119  :  82.  III.  Warren  County,  N.  J.,  N.  J.  Geol.  Surv.,  Ann.  Kept.  1873  :  80. 
IV.  Philpot,  Patrick  County,  Va..  U.  S.  Geol.  Surv.,  Bull.  380  :  219.  V.  Limestone  magnetite. 
Abingdon,  Va.,  Ibid.  VI.  Cornwall,  Pa.,  Amer.  Inst.  Min.  Engrs.,  Trans.  XIV  :  892. 
VII.  Iron  Springs,  Utah,  U.  S.  Geol.  Surv.,  Bull.  338.  VIII.  Hanover,  N.  Mexico,  U.  S.  Geol. 
Surv.,  Bull.  380  :  212.  IX.  Shasta  County  Calif.,  Econ.  Geol.,  Ill  :  472. 


2Fe2O3.         3MnO2.         4  MnO.         6  P2O6. 


Canada.  —  Two  important  magnetite  occurrences  in  eastern 
Canada  are  those  at  Bathurst,  N.  B.,  and  Moose  Mountain,  Ont. 
Some  magnetite  is  obtained  at  Torbrook,  N.  S.,  and  north  of  Lake 
Superior,  but  both  of  these  are  better  discussed  under  Hematite. 

Bathurst,  N.  B.  (83,  86,  96).  —  The  magnetite  here  forms  three 
bodies  or  groups  of  bodies  striking  approximately  north  and 
south,  with  walls  of  quartz-porphyry  and  quartz-free  porphyry. 
Diabase  is  also  present,  but  its  exact  relation  to  the  ore  is  not 
known.  Both  the  igneous  rocks  and  ore  are  more  or  less  schistose 
or  banded.  The  ore,  which  consists  largely  of  magnetite  with  a 
variable  amount  of  hematite,  is  fine  grained,  fine  to  coarse  banded, 
and  with  sharply-defined  walls.  Considerable  pyrite  is  at  times 
present,  and  veins  and  stringers  of  quartz  are  relatively  abundant. 
The  iron  content  ranges  from  39.6-58.7  per  cent;  sulphur  .009- 
.27  per  cent;  and  phosphorus,  ,385-1,222  per  cent, 


IRON   ORES  517 

The  ore  is  believed  to  be  a  replacement  of  the  schistose  quartz 
porphyry  along  sharply  defined  zones,  and  the  banded  structure 
may  be  an  original  one.  . 

Moose  Mountain,  Out.  (97).  —  This  deposit,  which  is  situated 
north  of  the  Sudbury  nickel  basin  (page  796)  is  one  of  the  largest 
in  Canada.  The  magnetite  shows  a  more  or  less  strongly  banded 
structure,  due  to  alternations  of  iron  ore  and  silica,  while  epidote 
sometimes  fills  fissures  in  the  ore,  which  are  often  bordered  by 
hornblende  that  passes  outwards  into  magnetite.  The  iron 
formation  which  lies  in  Keewatin  schists  is  steeply  tilted.  Ordi- 
nary banded  ore  runs  about  36  per  cent  iron  and  is  concentrated 
to  55  per  cent,  but  much  of  the  good  ore  exceeds  the  first  figure. 

Texada  Inland,  B.  C.  (89). — Contact-metamorphic  deposits 
of  magnetite  with  some  copper,  occurring  in  limestone  near 
granite  and  diorite  contacts  are  found  on  Texada  Island,  north- 
west of  Vancouver,  but  they  have  not  been  steadily  worked. 


FIG.  161.  —  Photomicrograph  of  thin  section  of  ore  from  Kiruna,  Sweden.    Black 
magnetite;   white,  apatite. 

Other  Foreign  Deposits  (1).  —  Two  of  the  most  remarkable  deposits  of, 
magnetite  known  in  the  World  are  those  of  Kiruna  and  Gellivare  in  northern 
Sweden.1  That  at  Kiruna  occurs  as  a  great  steeply  dipping  tabular  or 
dike-like  mass,  traceable  for  about  8  kilometers  in  the  hills  of  Kirunavaara 
and  Luossavaara  (Plate  XLIV,  Fig.  1  and  Fig.  161),  and  has  a  width  of 

^jSgren,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXVIII:  766,  1907.  Stutzer, 
Zeitschr.  prak.  Geol.,  XIV:  65  and  137, 1906. 


518  ECONOMIC  GEOLOGY 

32  to  152  meters.  The  total  tonnage  as  determined  from  outcrops  and  bor- 
;ngs  is  estimated  at  480,000,000  tons.  The  footwall  is  an  orthoclase  porphyry 
or  syenite,  while  the  hanging  wall  is  quartz  porphyry,  which  in  turn  is  overlain 
by  quartzites,  clay  slates  and  conglomerates,  supposedly  of  pre-Cambrian  age. 

The  ore  is  a  fine-grained  mixture  consisting  chiefly  of  magnetite  and  apa- 
tite (Fig.  161). 

Much  discussion  has  been  aroused  over  the  origin  of  these  ores.  Hogbom 
in  1898  thought  them  to  be  due  to  magmatic  segregation,  while  de  Launay 
argued  for  a  sedimentary  origin,  assuming  that  the  footwall  was  a  submarine 
flow,,  from  which  iron  chlorides  and  sulphides  emanated  in  gaseous  form 
and  were  then  oxidized  to  ferric  oxide,  which  later  was  changed  to  magnetite 
by  a  covering  flow  of  quartz  porphyry.  Stutzer,  with  probably  more  reason, 

Luossavaara 


Doktorns 


FIG.  162.  —  Section  across  Luossavaara  near  Kiruna,  Sweden.    (After  Lundbohm.) 

has  regarded  the  ore  as  a  dike,  whose  intrusion  was  preceded  by  the  footwall 
syenite,  and  followed  by  the  hanging  wall  quartz  porphyry. 

At  Gellivare  (Plate  XLIV,  Fig.  2),  the  ore  is  similar  to  Kiruna  mineralogic- 
ally,  but  coarser  grained.  It  occurs  as  steeply  dipping  irregular  lenses,  in  a 
gray  or  red  gneiss,  often  surrounded  by  a  curious  hornblendic  zone  (skarn). 
The  ore  is  probably  similar  in  origin  to  that  at  Kiruna,  but  has  been  strongly 
altered  by  metamorphism.1 

Other  large  magnetite  deposits  are  known  in  the  Ural  Mountains  at  Wys- 
sokaia  Gora  and  Goroblagodat.2  Of  historic  and  scientific  interest  are  the 
contact  metamorphic  deposits  of  magnetite  with  some  sulphides  found  in  the 
province  of  Banat,  Hungary,  and  first  described  by  von  Cotta.3 

Most  interesting  are  the  Cuban  4  deposits  lying  in  a  belt  stretching  eastward 
from  Santiago,  and  supplying  ore  which  is  chiefly  magnetite,  but  carries  some 
hematite  and  pyrite,  especially  in  its  upper  parts.  Prominent  among  the 
sedimentary  and  igneous  rocks  of  the  district  is  a  large  area  of  intrusive 

1  Sjogren,  loc.  cit.,  and  Lundbohm,  Internat.  Geol.  Cong.,  Sweden,  Guidebook, 
1910. 

2  Beck,  Erzlagersttaten,  3rd  ed.,  I:   29. 

3  Beck,  loc.  cit. 

4  Kemp,  Amer.  Inst.  Min.  Engrs.,  Bull.  105:   1801,  1915;   Lindgren,  Ibid.,  Bull. 
106:  2171,  1915.     These  contain  additional  references- 


PLATE  XLIV 


FIG.  1.  —  View  of  iron  ore  mines  in  Kimnavaara,  Sweden.    Open  cuts  near  top  in 
iron  ore.     Lower  slopes  chiefly  hanging  wall.     (H.  Ries,  photo.} 


FIG.  2.  —  Iron  deposit  at  Gellivare,  Sweden.  Note  pit  in  floor  connecting  with 
lower  workings.  Walls  of  cut  are  country  gneiss  and  in  part  "  skarn."  (H. 
Ries,  photo.) 

(519) 


520  ECONOMIC   GEOLOGY 

diorite,  which  encloses  fragments  of  an  older,  bedded  limestone.  The  ore 
deposits  consist  of:  (1)  small  streaks  to  larger  ones  in  limestone,  with  quartz, 
garnet  and  epidote,  gangue,  and  evidently  of  contact-metamorphic  origin; 
(2)  Great  tabular  masses  in  diorite,  but  showing  the  same  gangue  minerals 
as  the  first.  Kemp  regards  the  latter  as  replacements  along  fracture  zones  in 
the  diorite,  while  Lindgren  is  inclined  to  the  view  that  the  ore  bodies  are  a 
product  of  contact  metamorphism  exerted  by  the  diorite  on  included  masses 
of  limestone. 

Titaniferous  Magnetites  (24,  28,  30,  33a).  —  These  form  a 
peculiar  class  by  themselves,  and  with  one  or  two  exceptions  are 
found  always  associated  with  rocks  of  the  gabbro  family.  The 
ore  bodies  usually  represent  products  of  magmatic  segregation, 
and  may  occur:  (1)  within  the  eruptive  mass  but  grading  off  into 
it;  (2)  as  irregular  bands  (schlieren);  or  (3)  as  dikes  which  have 
separated  from  the  magma  at  greater  depth,  and  then  forced 
their  way  upward. 

An  exception  to  any  of  the  above  is  the  deposit  at  Cebolla  Creek, 
Colo.,  which  is  in  part  of  the  contact  metamorphic  type  (336). 

Many  titaniferous  magnetites  are  granular  aggregates  of  mag- 
netite and  ilmenite,  the  relation  between  the  two  minerals  being 
usually  those  of  a  granular  igneous  rock.  The  ilmenite  is  highly 
lustrous  with  a  rougher  surface,  while  the  magnetite  shows  duller, 
black,  cleavage  surfaces.  The  grains  of  the  latter  sometimes  have 
minute  intergrowths  of  ilmenite,  which  show  most  commonly  as 
lines  and  dots,  the  former  representing  sections  of  very  small 
ilmenite  lamellae  oriented  parallel  to  the  octahedral  faces  of  the 
magnetite. 

The  gangue  minerals  may  be  pyroxene,  brown  hornblende, 
hypersthene,  enstatite,  olivine,  spinel,  garnet,  and  plagioclase. 
The  ores  are  usually  low  in  phosphorus  and  sulphur,  but  V,  Cr, 
Ni,  and  Co  are  almost  always  present. 

Titaniferous  magnetites  are  found  in  many  parts  of  the  world, 
the  deposits  being  often  of  large  size,  but  their  possibilities  have 
been  greatly  overestimated.  This  is  due  to  the  fact  that  it  is 
often  impossible  to  separate  the  ilmenite  (non-magnetic)  from  the 
magnetite  (magnetic)  to  a  sufficient  degree,  owing  to  the  fine 
intergrowths  of  the  two. 

United  States  (28,  33a) .  —  In  this  country  titaniferous  mag- 
netites are  found  in  New  York,  New  Jersey,  Wyoming,  Minne- 
sota, Virginia,  Colorado,  etc.,  but  are  not  worked.  The  two 
localities  of  greatest  importance  are  Sanford  Hill,  in  the  Adiron- 
dack region  of  New  York,  and  Iron  Mountain,  Wyo. 


IRON   ORES 

The  following  analyses  illustrate  their  composition :  — 
ANALYSES  OF  TITANIFEROUS  MAGNETITES 


521 


1 

2 

3 

4 

5 

6 

7 

8 

FeO     . 
FesOa  - 

70.50  / 

—  C 

80.78 

i  27.95  [ 
115.85} 

79.78 

70.80 

28.84 
14.05 

1  24.55) 

(48.971 

51.44  2 

TiO2    . 

14.00 

12.09 

15.66 

12.08 

19.52 

10.11 

23.18 

16.76 

sio2  .  ; 

8.60 

2.02 

17.90 

.75 

1.39 

22.35 

2.15 

— 

A1203  . 

4.00 

2.58 

10.23 

4.62 

4.00 

5.26 

— 

— 

Cr2O3  . 

— 

2.40 

.51 

.32 

— 

Tr. 

— 

— 

V205    . 

— 

— 

.55 

Tr. 

— 

.18 

— 

— 

MnO  . 

— 

— 

Tr. 

.28 

— 

.43 

— 

— 

CaO    . 

1.60 

— 

2.86 

.13 

—  '. 

1.17 

— 

— 

MgO  . 

2.30 

— 

6.04 

2.04 

16.10 

— 

— 

H20    . 

— 

— 

.04 

— 

— 

.42 

— 

— 

P205    . 

— 

.03 

.14 

— 

.022  1 

.02 

— 

.97  1 

S 

— 

— 

— 

— 

.028 

.38 

.03 

— 

Na20  . 

— 

— 

— 

— 

— 

.44 

— 

— 

K20    . 

— 

— 

— 

— 

— 

.10 

— 

— 

Zn       , 

— 

— 

— 

— 

— 

.71 

— 

— 

Cu       .   . 

— 

— 

— 

— 

— 

.08 

— 

— 

Co,  Ni. 

— 

— 

— 

— 

— 

7.08 

— 

— 

Pb      ..... 

— 

.    — 

— 

— 

— 

-  Tr. 

—  • 

1.  Grape  Creek,  Col.  2.  Mayhew  Range,  Minn.  3.  Split  Rock,  N.  Y. 
4.  Greensboro,  N.  Ca. ;  Nos.  1-4,  U.  S.  Geol.  Surv.,  10th  Ann. 
Rept.,  Ill  :  377,  1899.  5.  Lake  Sanford,  N.  Y.,  N.  Y.  State  Mus., 
Bull.  119  :  163.  6.  Cumberland  Hill,  R.  I.,  Amer.  Jour.  Sci.,  Jan., 
1908.  7.  Iron  Mountain,  Wyo.,  U.  S.  Geol.  Surv.,  Bull.  315  :  209. 
8.  Marksville,  Va.,  Min.  Res.  Va.,  1907  :  419. 

Descriptions  of  two  localities  will  serve  to  illustrate  the  mode  of 
occurrence  of  these  titaniferous  ores. 

New  York  (28,  30). — Titaniferous  magnetite  deposits  of  large 
size  occur  in  the  Adirondack  region,  and  while  they  carry  TiO2  as  an 
essential  ingredient,  the  percentage  of  this  element  may  vary  con- 
siderably. Thus  in  the  Adirondack  ores  it  is  at  least  8  to  9  per 
cent  (TiO2),  and  averages  15  per  cent. 

The  ores  are  closely  associated  with  gabbro-anorthosite  intrusions, 
and  are  found  chiefly  in  Essex  and  southern  Franklin  counties. 
At  Lake  Sanford,  where  the  most  important  ore  bodies  occur,  the 
small  deposits  are  found  in  gabbro  dikes  cutting  the  anorthosite  and 
having  a  tabular  form  conformable  with  the  strike  of  the  dikes,  but 

i  P.  2Fe. 


522 


ECONOMIC   GEOLOGY 


large  ones  occur  in  the  anorthosite  and  may  be  segregations  during 
cooling,  or  actual  intrusions  forced  into  the  anorthosite  after  partial 
consolidation. 

The  ores  are  essentially  magnetite  and  ilmenite,  the  richest  show- 
ing little  else  and  running  about  60  per  cent  Fe.  The  magnetite 
grains  are  recognizable  by  parting  planes  parallel  to  the  octahedron 
and  smooth  breaks,  while  the  ilmenite  grains  show  a  rough  fracture, 
brighter  luster,  and  but  slight  magnetism. 

Other  minerals  present  are  plagioclase,  pyroxene,  hornblende, 
biotite,  oli vine,  garnet,  pyrite,  apatite,  spinel,  and  quartz.  The 
usual  order  of  crystallization  is  reversed,  being  silicates,  pyrite, 
ilmenite,  magnetite.  Analyses  of  the  Sanford  deposits  show 
70.73-87.60  Fe3O4,  .87-2.46  Si02;  9.45-20.03  TiO2;  .53-4.00  ALA; 
.007-.022P;  .027-.028  S. 

The  following  results  were  obtained  by  magnetic  separation  after  crush- 
ing to  40  mesh.  Finer  crushing  would  probably  improve  the  product. 


1 

2 

3 

MAGNETITE 

CONCENTRATE 

ILMENITE  AND 
OTHER  MINERALS 

Fe2O3       *  -  .     .     .     .     . 

559 

54.39. 

14.28 

FeO 

275 

2866 

30.93 

TiO2    ....... 

14.0 

8.93 

45.23 

Wyoming  (24). — An  occurrence  of  titaniferous  magnetite  of  some 
importance  is  found  at  Iron  Mountain  in  southeastern  Wyoming.  Iron 
Mountain  is  a  ridge  300  to  600  feet  wide,  and  1|  miles  long,  which  rises 
sharply  from  the  anorthosite  hills  to  the  east  and  pre-Cambrian  uplands 
to  the  west.  The  pre-Cambrian  complex  near  the  iron  ore  dike  consists 
of  three  granular  igneous  rocks,  viz.  anorthosite,  iron  ore,  and  granite, 
the  anorthosite,  or  oldest,  being  cut  by  dikes  and  lenticular  masses  of  iron 
ore  and  granite. 

The  ore,  which  forms  a  dike  H  miles  long,  40  to  300  feet  wide,  and  has 
a  northerly  strike,  is  sharply  bounded  on  both  sides  by  anorthosite,  and 
paralleled  by  several  smaller  dikes.  It  is  a  black,  granular,  holocrystal- 
line  rock,  which  carries  as  impurities  biotite,  olivine,  and  feldspar.  The 
iron  content  averages  about  50  per  cent. 

It  is  suggested  (Ball)  that  the  ore  and  anorthosite  are  differentiation 
products  from  a  common  magma,  the  iron  having  been  intruded  after 
the  complete  solidification  of  the  anorthosite;  but  the  relationship  of  the 
two  is  shown  by  the  presence  in  each  of  similar  minerals,  although  their 
proportions  are  different. 


IRON   ORES 


523 


The  granite  is  probably  the  youngest  of  the  pre-Cambrian  rocks,  and 
grades  into,  as  well  as  being  cut  by,  a  biotite-pegmatite  which  carries  some 
magnetite. 

Fig.  164  shows  a  thin  section  of  a 
low  grade  titaniferous  ore  found  in 
gabbro  at  Cumberland,  Rhode  Island. 

Magnetite  Sands.  —  These  are 
found  in  those  regions  where  the 
beach  sands  are  composed  of 
weathering  products  of  rnetamorphic 
and  igneous  rocks.  The  sorting 
action  of  the  waves  serves  to  carry 
the  heavy  mineral  grains  high  up  on 
the  beaches,  where  they  form  black 
stieaks,  composed  mostly  of  mag- 
netite (usually  titaniferous),  mixed 
with  monazite,  apatite,  and  other 
heavy  minerals. 

Deposits  are  known  in  this 
country  on  the  shores  of  Lake 
Champlain,  Long  Island,  etc.,  but 
they  are  of  small  extent  as  well  as 
lacking  in  quality. 

New  Zealand  and  Brazil  are  said 
to  possess  magnetite  sands  of  com- 
mercial value. 

Sandstones  of  Upper  Cretaceous 
age,  and  carrying  titaniferous  magnet- 
ite are  known  in  Montana,  but  are  of 
no  commercial  value  (36a). 


a          be          d          e 

FIG.  163.  —  Map  of  Iron  Mountain, 
Wyo.,  titaniferous  magnetite  de- 
posit, a,  post-Devonian;  6,  anor- 
thosite;  c,  granite;  d,  gneiss;  e,  ore. 
(After  Kemp,  Zeitschr.  prak.  Geol., 
1905.) 


FIG.  164.  —  Section  of  Cumberlandite  (Rhodose)  from  Cumberland,  R.  I.     Black 
ilmenite  and  magnetite;  white,  olivine.     X30. 


524  ECONOMIC  GEOLOGY 

Canada  (85,  88) .  —  Titaniferous  magnetites  have  been  found 
at  a  number  of  localities  in  Ontario,  those  of  the  Chaffey  and 
Matthews  mines  being  well  known.  Another  large  deposit 
occurs  at  St.  Urbain,  Quebec  . 

Along  the  St.  Lawrence  River,  in  Saguenay  County,  Quebec 
(88),  magnetite  sands  are  somewhat  abundant.  Where  the  sands 
have  been  worked  over  by  the  waves,  the  magnetite  grains  have 
been  concentrated  into  lenses  distributed  through  the  ordinary 
sand.  Analyses  of  the  sand,  etc.,  are  given  below: 

INSOLU- 

Fei  TiOji         BLE  RES-  P  S 

IDUE 

Crude  sand 14.7         4.43         76.00         .006          .006 

First  concentrate     ...          67.2         3.51  7.45         .043          .012 

First  tailings 8.3         4.7 

1  Soluble  iron  only. 

Other  Foreign  Deposits. — A  number  of  titaniferous  magnetite  deposits 
are  found  in  Scandinavia.  The  best  known  is  that  of  the  Ekersund-Soggendal  l 
on  the  south  coast  of  Norway,  where  the  labradorite  rock  contains  some 
large  ore  bodies.  Routivare  in  northern  Sweden  has  a  large  mass  of  spinel- 
bearing  titaniferous  magnetite  in  altered  gabbro,  while  at  Taberg  in  southern 
Sweden  is  still  another  large  deposit,  which  occurs  in  olivine-gabbro  and  was 
recorded  as  early  as  1806. 

HEMATITE 

This  is  by  far  the  most  important  ore  of  iron  in  the  United  States, 
having  in  1914  formed  over  90  per  cent  of  the  total  production, 
and  about  85  per  cent  of  the  hematite  mined  came  from  the  Lake 
Superior  region.  It  is  also  an  important  ore  in  some  other  coun- 
tries. Hematite  may  occur  mixed  with  magnetite  in  magmatic 
segregations  (Kiruna,  Sweden,  page  517)  and  contact-metamorphic 
deposits  (29),  as  beds  in  sedimentary  rocks  (51-59),  as  replace- 
ments in  limestone  (page  548) ;  as  irregular  deposits  formed  by 
circulating  surface  waters  (page  525) ;  and  as  specular  hematites 
in  metamorphic  rocks  (page  525) . 

Distribution  of  Hematite  Ores  in  the  United  States  (Fig.  153).— 
At  the  present  day  there  are  but  two  very  important  hematite- 
producing  regions,  in  the  United  States,  viz.  the  Lake  Superior 
region  and  the  Birmingham,  Alabama,  district.  Other  areas 
which  are  worked  will  also  be  referred  to,  but  they  are  less  im- 
portant. 

1  Vogt,  Erusch  u.  Beyschlag,  Ore  Deposits,  Translation,  I:  250,  1914. 


IRON   ORES  525 

Lake  Superior  Region  (45,  47). — Under  this  head  are  included  a 
great  series  of  deposits  lying  in  the  region  surrounding  the  south 
and  west  sides  of  Lake  Superior  (47).  The  rocks  are  of  remote 
geologic  age,  and  the  age  and  names  of  the  iron-bearing  formations 
are  as  follows: 

Algonkian  system. 

Keweenawan  series:   Carries  titaniferous  gabbros  in  Minnesota  but  no 

hematite. 
Huronian  series: 

Upper  Huronian  (Animikie  group). 
Biwabik  formation  of  Mesabi. 
Animikie  group  of  Animikie  district,  Ontario. 
Ironwood    formation,    Penokee — Gogebic    district,    Michigan    and 

Wisconsin. 

Vulcan  formation,  Menominee  and  Calumet  districts,  Michigan. 
Vulcan  iron-bearing  member  of  Crystal  Falls,    Iron  River,   and 

Florence  districts.  Michigan  and  Wisconsin. 
Gunflint  formation,  Gunflint  Lake  district,  Canada,  and  Vermilion 

district,  Minnesota. 

Bijiki  schist,  Marquette  district,  Michigan. 
Deerwood  iron-bearing  member,  Cuyuna  district,  Minnesota. 
Middle  Huronian.1 

Negaunee  formation,  Marquette  district,  Michigan. 
Archaean  system.1 
Keewatin  series : 

Soudan  formation,  Vermilion  district,  Minnesota. 
Helen  formation,  Michipicoten  district,  Ontario. 
Unnamed  formation  of  Atikokan  district,  Ontario. 
Several  non-productive  formations  hi  Ontario. 

The  ore-bearing  districts  have  been  studied  in  considerable 
detail,  but  the  intervening  parts  are  less  well  known,  and  it  is 
therefore  difficult  to  correlate  the  major  geological  units  of  the 
several  districts. 

Character  of  formations.  —  The  Archaean  includes  a  complex  series 
of  acid  and  basic  igneous  rocks,  and  two  or  more  sedimentary  for- 
mations, including  the  iron  formations  and  slate  of  the  Keewatin. 
The  Algonkian  includes  four  unconformable  sedimentary  series,  all 
associated  with  igneous  rocks,  the  entire  succession  being  separated 
by  an  unconformity  from  the  Archaean  below  and'  the  Potsdam 
above. 

The  iron  ores  occur  as  concentrations  in  the  so-called  iron  forma- 

1  The  Lower  Huronian  and  Laurentian,  although  present  in  the  series  of  forma- 
tions found  in  this  region,  do  not  carry  any  ore  bodies. 


526  ECONOMIC   GEOLOGY 

tions,  which  range  in  thickness  from  a  few  hundred  to  a  thousand 
feet. 

In  their  present  form  these  iron  formations  represent  alterations 
of  chemically  deposited  sediments,  such  as  cherty  iron  carbonates, 
which  are  usually  interbedded  with  normal  clastic  sediments  such 
as  slate  and  quartzite. 

In  general  terms  the  iron  formations  may  be  described  as  consisting 
mainly  of  chert  or  quartz  and  ferric  oxide,  usually  segregated  into  bands, 
but  sometimes  irregularly  mixed.  Jasper  is  a  banded  rock  of  highly  crystal- 
line character  with  the  quartz  layers  colored  red.  Ferruginous  chert  differs 
from  it  in  being  less  crystalline,  and  with  the  quartz  either  banded  or  irreg- 
ularly mingled.  This  latter  type  is  known  as  taconite  in  the  Mesabi  district. 
Other  phases  of  the  iron  formation  are  clay  slates,  paint  rocks  (alterations  of 
preceding),  amphibole-magnetite  schists,  cherty  iron  carbonate,  hydrous 
ferrous  silicate  (greenalite),  and  iron  ores. 

The  original  iron  rocks  were  cherty  iron  carbonate,  ferrous 
silicate,  and  pyritic  iron  carbonate,  and  unaltered  remnants  of 
these  are  still  found.  . 

The  average  iron  content  of  all  the  original  phases  of  the  iron- 
bearing  formations  for  the  region,  excluding  interbedded  slates, 
is  24.8  per  cent,  and  the  iron  ores,  though  of  great  commercial 
importance,  form  but  a  small  percentage  of  the  rocks  of  the  iron- 
bearing  formations.  This  percentage  varies  from  .062  to  2.00 
per  cent. 

The  iron  ores  are  the  result  of  subsurface  alterations  of  richer 
layers  of  the  iron-bearing  rocks,  and  are  localized  both  where 
these  alterations  have  been  most  effective,  and  structural  features 
have  served  to  collect  the  underground  waters. 

The  existence  of  ore  then,  depends  largely  on  secondary  con- 
centration. Of  great  importance  in  determining  the  distribution 
of  the  ores  are  impervious  basements  and  fractures,  the  former 
often  shaped  like  pitching  troughs. 

The  ore  bodies  vary  widely  in  their  form,  although  steeply 
dipping  deposits  are  the  rule,  with  the  horizontally  tabular  ones 
of  the  Mesabi  range  forming  a  marked  exception. 

The  ores  of  the  Lake  Superior  region  vary  from  hard  blue  ores 
to  soft  earthy  ones.  They  are  mostly  hematite  with  small  quanti- 
ties of  limonite,  but  some  magnetite  is  known  in  the  Marquette 
district. 

The  following  tables,  taken  from  Van  H-ise  and  Leith,  show  the 
average  composition  and  range  of  Lake  Superior  ores.  Many 


IRON   ORES 


527 


additional  ones  can  be  found  in  the  report's  on  Mineral  Resources 
issued  annually  by  the  United  States  Geological  Survey. 


AVERAGE  COMPOSITION  OF  TOTAL  YEARLY  PRODUCTION  OF  LAKE  SUPERIOR 
IRON  ORE  FOR  1906  AND  1909 


1906 

1909 

Moisture        .....                    .   i»^  .     » 

11  28 

Analysis  of  ore  dried  at  212°  F.: 
Iron       .     .     .     .-    .  /  .     .     .     . 

59  80 

58  45 

Phosphorus 

081 

091 

Silica 

6  83 

7  67 

Alumina    

1  60 

2  23 

Manganese                         .          .... 

1        '  : 

71 

Lime          .     .     . 

54 

Magnesia  

„ 
•  2  .  70  • 

55 

Sulphur      

06 

Loss  by  ignition       

3.92 

4.12 

The  range  in  percentages  shown  by  the  analyses  from  which  the 
foregoing  averages  are  derived  is  as  follows: 

RANGE  OF  EACH  CONSTITUENT  OF  ORES  YIELDING  THE  ABOVE  AVERAGES 


1906 

1909 

Moisture  at  212°  F.                  ... 

50  to  17  40 

Range  of  ore  dried  at  212°  F. 

38  .  15  to  66  .  07 

35  .  74  to  65  .  34 

Phosphorus    

008  to      85 

008  to  1  .  28 

Silica 

3  21  to  40  97 

2  50  to  40  77 

M^  anganese 

00  to    7  20 

Alumina    

20  to    3  59 

.16  to    5.67 

Lime                         .          .... 

00  to    4.96 

Magnesia 

00  to    3  98 

Sulphur 

003  to  1  87 

Loss  on  ignition      

.00  to  10.0 

.40  to  11.40 

In  addition  there  is  given  below  two  other  tables  compiled  by 
Birkenbine. 


528 


ECONOMIC   GEOLOGY' 


TYPICAL  ANALYSES  OF  LAKE  SUPERIOR  IRON  ORES 


CONTENT 

MARQUETTE 
RANGE 

MENOMINEE 
RANGE 

GOGEBIC 

RANGE 

VERMILION 
RANGE 

MESABI 
RANGE 

Iron  . 

56.5 

55.2423 

56.308 

61.36 

56.0996 

Phosphorus      .     . 
Silica      .... 

.0353 
4.584 

.0594 
6.7693 

.0338 
3.3961 

.0373 
4.2545 

.0365 
3.4867 

Sulphur       .     .     . 
Moisture     .     .     . 

.0089 
11.85 

6.525 

10.828 

4.5649 

12.3158 

ANALYSES  OF  SILICEOUS  ORES 


CONTENT 

MARQUETTE 
RANGE 

.    MENOMINEE 
RANGE 

VERMILION 
RANGE 

Iron             

42.27 

42.129 

51.1938 

Phosphorus      .... 

.0316 
35.834 

.0244 
34.141 

.0498 
22.3642 

Sulphur       .     . 

.0099 

Moisture 

1  23 

2.2 

3.21 

The  Lake  Superior  region  includes  the  following  districts: 


DISTRICTS 

STATE 

AREA 
SQ.MI. 

Marquette    
Menominee             

Mich. 
Mich 

330 
112 

Crystal  Falls 

Mich 

540 

Iron  River    

Mich. 

210 

Florence                                 .... 

Wis 

75 

Calumet  and  Felch  IVItn 

Mich 

9QO 

Penokee-Gogetic  

Mich.-Wis. 

450 

Vermilion  1                                 ... 

JVlesabi      j 

Minn. 

1400 

Cuyuna                                  .... 

M  inn  . 

300 

IVlichipicoten 

Can 

140 

The  general  mode  of  occurrence  of  the  ore  in  several  of  these 
is  shown  in  Figs.  166  to  168,  and  the  more  important  ones  are 
referred  to  individually  below. 

Marquette  Range  (48).  —  This  occupies  a  rather  large  area  west  and 
southwest  of  Marquette,  Michigan,  and  carries  iron  formations  in  both  the 


IRON   ORES 


529 


Upper  and  Middle  Huronian,  the  latter  being  the  more  important.  That  of 
the  Upper  Huronian  is  underlain  by  quartzite  and  covered  by  slate,  while  the 
Middle  Huronian  iron  formation  is  underlain  by  slate  which  in  turn  rests  on 
quartzites.  Igneous  intrusions  of  Keweenawan  age  are  common.  The 
structure  of  the  range  is  that  of  a  great  east-west  synclinal  basin  containing 


FIG.  165.  —  Map  of  Lake  Superior  iron  regions,  shipping  ports,   and  transporta- 
tion lines.     (After   Van  Rise  and  Leith,    U.   S.   Geol.   Surv.,   Mon.  LII.) 


a  number  of  minor  folds,  and  while  the  ores  occur  on  both  limbs  of  the  basin, 
they  are  most  abundant  on  the  northern  one. 

The  ores  may  be  divided  into  three  classes,  namely,  (1)  ores  at  the 
base  of  the  iron-bearing  Negaunee  (Middle  Huronian)  formation,  (2)  the 
ores  within  the  Negaunee  formation,  (3)  detrital  ores  at  the  base  of  the 
Goodrich  (Upper  Huronian)  quartzite.  Ores  of  the  first  and  second 
class  are  mostly  soft  hydrated  hematite,  while  those  of  the  third  class  are 
hard  specular  ores  with  some  magnetite  from  metamorphism  due  to 
greater  movements  along  the  contact  of  the  Middle  and  Upper  Huronian 
during  the  faulting  within  these  rocks  themselves. 

Menominee  Range  (39).  —  While  this  carries  iron  formations  in  both 
the  Middle  and  Upper  Huronian,  only  the  former  are  commercially  im- 
portant and  are  confined  to  the  southern  part  of  the  district.  The  iron 
ores  are  mainly  gray,  finely  banded  hematite  with  lesser  amounts  of  a 
flinty  hematite  which  shows  local  banding. 


530 


ECONOMIC  GEOLOGY 


FIG.  166.  —  Sections  of  iron-ore  deposits  in  Marquette  range.     (After  Van  Hi. 


FIG.  167.  —  Generalized  vertical  section  through  Penokee-Gogebic  ore  deposit  and 
adjacent  rocks  ;    Colby  mine,  Bessemer,  Mich.     (After  Leiih,~) 


Penokee-Gogebic  Range  (42).  —  The  ores  occur  in  Upper  Huronian, 
the  iron  formation  being  overlain  by  slate  and  underlain  by  quartzite  and 


532 


ECONOMIC   GEOLOGY 


black  slate.  The  latter  is  covered  by  a  gabbro  of  Keweenawan  age, 
which  is  found  in  contact  with  the  iron  formation  in  places  and  has  altered 
it  to  jasper  and  amphibole-magnetite  rock.  Most  of  the  iron  formation, 
however,  is  ferruginous  chert.  The  steeply  dipping  sedimentary  rocks 
are  cut  by  dikes  of  basic  igneous  rocks,  thus  forming  troughs  in  which  the 
ores  are  concentrated.  Most  of  the  deposits  reached  depths  of  1000  feet 
and  upwards,  but  the  horizontal  extent  is  small.  While  soft  hydrated 
hematite  is  the  normal  type  of  ore,  still  the  hard  slaty  ore  is  not  uncom- 
mon. Manganese  is  found  in  a  few  deposits. 

Mesabi  Range  (44).  —  The  rocks  of  this  region  are  less  folded  and 
metamorphosed,  and  dip  slightly  to  the  southeast.  The  iron  formation, 
which  is  mainly  ferruginous  chert,  is  overlain  by  a  thick  slate  and  under- 
lain by  a  thin  quartzite,  which  in  turn  rests  on  granite,  or  graywacke  and 
slate  of  lower  Middle  Huronian.  At  the  eastern  en'd  of  the  range  the  iron 
formation  has  been  metamorphosed  to  amphibole-magnetite  rock  by  a 
gabbro  intrusion.  The  iron-ore  deposits  are  very  irregular  in  shape,  but 
their  horizontal  extent  is  great  as  compared  with  their  depth  (Fig.  168), 
most  of  them  being  less  than  200  feet.  The  mining  is  done  mainly  by  open 
pits  (PI.  XLV),  and  the  ore  is  a  rather  soft  hematite  of  high  grade.  It  pre- 
serves the  stratification  of  the  original  iron  formation  and  in  places  is  found 
grading  into  the  latter. 


FIG.  168. — Generalized  vertical  section  through  Mesabi  ore  deposit  and  adjacent 

rocks.     (After  Leith.) 

Vermilion  Range  (40).  —  The  chief  ore  deposits  occur  in  the  highly 
folded  and  metamorphosed  Keewatin  rocks,  and  the  iron  formation  is 
largely  altered  to  jasper.  The  country  rock  is  mostly  greenstones  in 
which  the  jasper  occurs  in  basins  or  troughs.  The  ores  associated  with 
the  jasper  in  these  troughs  usually  have  a  greenstone  footwall  and  con- 
sist of  dense  hard  red  or  blue  hematite,  which  is  sometimes  brecciated  but 
rarely  specular. 

Cuyuna  Range  (48).  —  This  range  lies  to  the  southwest  of  the  Mesabi 
range  and  shows  a  series  of  small  northeast-southwest  anticlines  in  a 
broad  synclinal  basin  on  whose  northern  limb  the  Mesabi  range  is  situ- 
ated, while  on  the  southern  limb  we  find  the  Penokee.  Owing  to  the 
limited  number  of  outcrops  and  lack  of  development  at  the  present  time, 
the  geology  is  not  yet  perfectly  known,  but  the  formations  seem  to  include 
quartzite  and  its  altered  equivalents,  iron  formations,  slate,  and  intrusive 
granite  and  diorite.  The  ores  form  the  altered  and  concentrated  upper 


PLATE  XLVI 


FIG.  1.  —  Iron  mine,  Soudan,  Minn.  Shows  old  open  pit  with  jasper  horse  in  middle. 


FIG.  2.  —  View  of  limonite  pit  near  Ironton,  Pa.     (H.  Ries,  photo.) 

(533) 


534  ECONOMIC  GEOLOGY 

parts  of  the  steeply  dipping  iron-formation  strata,  which  are  exposed  by 
the  erosion  of  the  anticlines.  The  hanging  wall  is  commonly  chloritic 
slate  and  iron  carbonate  in  varying  proportions  and  degrees  of  alterations, 
while  the  footwall  is  either  a  quartz  schist  or  amphibole-magnetite  schist. 
The  ore  bodies  thus  far  found  seem  to  be  in  the  form  of  lenses  100  to  250 
feet  thick,  with  their  longer  dimensions  parallel  to  the  highly  tilted  bed- 
ding of  the  series. 

Canada  (79,  80,  81).  —  On  the  Canadian  side  of  the  boundary  there  are 
a  number  of  iron-bearing  areas  (Fig.  165),  only  one  of  which  is  of  importance, 
viz.  the  Michipicoten  district.  Here  the  iron-bearing  formation  lies  in  the 
Keewatin,  the  geology  and  structure  being  similar  to  the  Vermilion  district  of 
Minnesota.  The  iron  formation  includes  sideritic  and  pyritic  cherts,  jaspers, 
siderite,  schists  and  iron  ore,  and  the  Helen  ore  body  lies  in  an  amphitheatre 
with  iron  carbonate  on  the  east,  ferruginous  chert  on  the  north,  and  tuffs  on 
the  south,  while  a  diabase  dike  crosses  the  basin. 

The  ore,  which  chemically  resembles  the  hydrous  Mesabi  ores,  dips  east- 
ward, apparently  under  the  carbonate,  but  exploration  below  the  latter  has 
developed  a  very  large  body  of  pyrite. 

Origin.  —  The  origin  of  these  ores  has  for  years  been  a  puzzling 
problem  to  geologists.  Foster  and  Whitney  considered  them 
eruptive,  while  Brooks  and  Pumpelly  looked  upon  them  as  altered 
limonite  beds. 

The  work  of  Van  Hise  and  Leith  has  shown  us  that  the  Lake 
Superior  ores  were  concentrated  in  certain  sedimentary  iron  forma- 
tions, and  it  was  at  first  believed  that  these  sediments  were  derived 
from  the  weathering  of  land  areas  containing  much  igneous  rock. 

Further  study  has  led  them  to  conclude,  however,  that  the  iron 
formations  have  not  only  been  derived  in  this  way,  but  that  the 
iron  has  actually  been  contributed  by  greenstone  magmas  directly 
to  the  water  in  magmatic  solutions  and  that  there  are  all  intermediate 
stages  between  the  two  processes  (41). 

The  iron  ore  as  first  deposited  consisted  essentially  of  chemically 
precipitated  iron  carbonate  or  ferrous  silicate  (greenalite)  with 
some  ferric  oxide,  all  finely  interlayered  with  chert. 

Later  on,  when  these  sediments  were  uplifted  to  form  the  land 
surface  and  exposed  to  weathering,  the  ferrous  compounds,  the 
siderite  and  greenalite,  were  oxidized  to  hematite  and  limonite. 
While  this  occurred  mainly  in  place,  some  of  the  iron  was  carried 
off  and  redeposited  elsewhere.  This  resulted  in  a  ferruginous  chert 
carrying  less  than  30  per  cent  of  iron. 

Further  concentration  of  the  iron  to  50  per  cent  or  over  was  accom- 
complished  mainly  by  the  silica  being  leached  from  the  bands  of 
ferruginous  chert. 


IllON   ORES  535 

Where  the  concentration  of  the  ore  has  occurred  in  troughs,  the 
chemistry  of  the  process  is  thought  to  be  as  follows :  — 

Part  of  the  ferric  oxide  was  deposited  as  an  original  sediment  contain- 
ing silica  and  other  impurities,  or  in  some  cases  as  sulphides  or  carbonates. 
This  was  later  enriched  by  the  addition  of  iron  carbonate.  These  were 
originally  contained  in  the  rocks  near  the  surface,  and  became  oxidized 
by  percolating  waters,  which  took  up  the  carbon  dioxide  liberated,  and 
were  thus  able  to  dissolve  iron  carbonates  or  silicates,  which  they  came 
in  contact  with  in  their  downward  course  toward  the  troughs  in  which  the 
ore  is  found. 

The  precipitation  of  the  ore  was  then  caused  by  these  solutions  meet- 
ing with  others  which  had  filtered  in  by  a  more  open  and  direct  path  from 
the  surface,  and  hence  contained  some  free  oxygen,  which  converted  the 
dissolved  iron  compounds  into  oxides. 

The  same  solutions,  carrying  carbon  dioxide,  dissolved  the  alkalies  out 
of  the  basic  igneous  rocks,  and  these  waters  were  then  able  to  dissolve 
silica.  In  some  cases  the  solution  of  silica  proceeded  faster  than  the 
deposition  of  the  iron  ore,  and  made  the  rock  quite  porous.  The  general 
result  was  therefore  a  concentration  of  the  iron  and  removal  of  silica. 

The  weathering  processes  have  yielded  mainly  soft  ores  and  ferru- 
ginous cherts,  while  metamorphism  has  formed  hard  red  and  blue 
specular  ores  and  brilliant  jaspers,  as  well  as  changed  the  iron  for- 
mation into  amphibole-magnetite  schists. 

Most  of  the  rich  ores  are  found  above  the  1000-foot  level,  except  in  the 
Mesabi  district,  where  the  deposits  are  shallow,  as  compared  with  their 
horizontal  extent,  some,  however,  being  over  400  feet  deep. 

In  the  early  period  of  mining  many  of  the  Lake  Superior  bodies  were 
worked  as  open  cuts,  but  with  depth  underground  working  has  been  re- 
sorted to.  There  are  many  deposits  in  the  Mesabi  district  which  are 
worked  as  open  pits  from  which  the  granular  ore  is  dug  with  a  steam 
shovel  and  loaded  directly  on  to  the  ore  cars,  which  are  run  along  the 
working  face  (PL  XLV). 

The  market  value  of  the  ores  is  based  on  the  iron  contents,  percentage 
of  water,  and  amount  of  phosphorus,  and  at  times  the  manganese  contents 
is  taken  into  consideration.  Some  objection  was  at  first  raised  to  the  fine 
character  of  the  Mesabi  ore  and  its  tendency  to  clog  the  blast  furnace, 
therefore  requiring  the  admixture  of  lump  ore  from  the  other  ranges ; 
but  this  objection  has  disappeared,  and  some  furnaces  now  use  over  75 
per  cent  of  Mesabi  ore  in  their  charge. 

The  Lake  Superior  iron  ore  region  is  not  only  the  most  important  in 
the  world,  but  the  production  of  some  of  the  individual  mines  is  startling. 
(See  production  of  individual  mines  at  end  of  this  chapter.)  The  Mar- 
quette  range  was  developed  as  early  as  1849,  the  Mesabi  as  late 
as  1892,  and  the  Cuyuna  some  years  after  this.  The  total  yield  of 
the  Lake  Superior  region  from  1854  to  the  end  of  1914  has  been  666,268,797 
long  tons.  While  the  output  has  been  phenomenal,  und  the  supply  large, 


536 


ECONOMIC   GEOLOGY 


high-grade  ore  is  no  longer  abundant,  and  much  ore  running  high  in  silica 
is  now  shipped. 

Wyoming  (60).  —  Important  deposits  of  hematite  are  found  in  the 
pre-Cambrian  schists  at  several  localities  in  Wyoming,  viz.  in  the  Hart- 
ville  District,  Laramie  County,  and  near  Rawlins,  in  Carbon  County. 

The  Hartville  deposits  form  a  portion  of  the  Hartville  uplift, 
which  is  a  broad,  low  dome  similar  to  that  formed  by  the  Black  Hills, 
and  while  the  iron  range  extends  from  Guernsey  to  Frederick,  a 
distance  of  8  miles,  the  productive  area  extends  only  from  a  point  2 
miles  northeast  and  1  mile  southeast  of  Sunrise. 

The  pre-Cambrian  sediments  have  been  folded  into  a  complex 
synclinorium,  and  faulting  has  been  a  common  phenomenon,  while 
the  brecciation  which  accompanied  both  the  folding  and  faulting 
was  an  important  structural  factor  in  the  ore  formation. 

The  most  important  ore  bodies  are  lenses  occurring  in  the  schist 
along  a  limestone  footwall,  the  ore  either  replacing  the  schist  or  to  a 
lesser  extent  filling  the  joint,  fault,  and  breccia  cavities.  These 
lenses  range  up  to  1000  feet  in  length,  and  conform  to  the  foliation  of 
the  schists.  Detrital  ores  derived  from  the  foregoing  are  also  found. 

The  following  geological  section  is  involved  :  — 


Pleistocene 

Terrace  gravels,  alluvium,  and  wash. 

Tertiary  (Arikaree) 

Sandstone. 

Jura-Trias  and  Cretaceous 

Carboniferous  nearly  flat 

Hartville   650'    thick.     White   or   gray   lime- 
stone.    Red  sandstone. 
Unconf  ormi  ty  . 
Guernsey  150'   thick.     Conglomeratic  quartz- 
ite  or  sandy  limestone. 

Pre-Cambrian  rocks,    the 
stratified      ones      with 
steep  dip. 

Quartzose  beds,  partly  conglomerate  and  asso- 
ciated jaspers. 
Unconformity. 
Interbedded  siliceous  limestones  and  musco- 
vite  and  biotite  schists  with  beds  and  lenses 
of  quartz  and  jasper  rock. 
Intrusives,  diabase,    aplites    and    pegmatites, 
biotite  granite,  gabbros,  diorites,  and  por- 
phyrites,  derivative  hornblende  and  chlorite 
schists. 

The  ores  are  high-grade  hematites  (chiefly  hydrated),  averaging 
over  60  per  cent  iron.  Sulphur  is  absent,  silica  may  be  high,  and 
much  of  the  ore  is  non-Bessemer.  Two  grades  of  ore  are  recognized, 


IRON   ORES  537 

viz.  a  hard   gray  hematite,  and  a  soft  greasy  one  of  brown-red 
color. 

Siderite  and  limonite  are  of  subordinate  importance,  while  the 
associated  minerals  are  calcite,  quartz,  gypsum,  chalcedony,  barite, 
chrysocolla,  etc.  The  copper  minerals  occur  in  the  fractures  in  the 
hematite.  Both  types  of  hematite  grade  into  the  schist,  but  much 
of  the  soft  ore  has  been  derived  from  the  hard  by  percolating  waters. 

Ball  assigns  an  epigenetic  origin  to  the  ore,  believing  that  it  was 
deposited  by  descending  waier,  because  (1)  the  ore  is  along  zones  of 
maximum  downward  circulation,  (2)  lenses  and  veins  are  found  along 
joints  at  a  distance  from  the  main  body,  and  (3)  the  associated  min- 
erals^ quartz,  calcite,  and  limonite,  are  all  water-formed  ones.  The 
magnetite  and  iron  pyrite  of  the  schist  lying  above  the  limestone  foot- 
wall  are  regarded  as  the  source  of  the  iron.  During  pre-Cambrian 
times  there  was  extensive  erosion  of  this  schist,  and  a  downward 
transferal  of  this  iron  by  carbonated  surface  waters  flowing  along 
the  impervious  limestone  footwall,  where  it  was  precipitated  by 
oxygen-bearing  waters  coming  by  a  more  direct  path. 

Clinton  Ore  (51-59).  —  This  ore,  which  is  also  called  fossil,  pea, 
or  dyestone  ore,  was  given  the  first  name  on  account  of  the  ore  bed 
having  been  originally  discovered  at  Clinton,  N.  Y.  It  is  one  of 
the  most  persistent  iron-ore  deposits  that  is  known  (Fig.  169),  for 
it  occurs  at  most  points  where  rocks  belonging  to  the  Clinton 
stage  of  the  Silurian  are  found. 

The  following  districts  may  be  enumerated  as  showing  the 
location  of  the  more  important  deposits:  (1)  west  central  New 
York;  (2)  several  narrow  belts  in  central  Pennsylvania;  (3)  Al- 
leghany  County,  Virginia;  (4)  a  belt  through  Lee  and  Wise 
counties,  Virginia,  extending  southwestward  into  the  La  Follette 
district  of  Tennessee;  (5)  narrow  belts  in  the  region  of  Chat- 
tanooga, Tennessee;  (6)  Birmingham,  Alabama;  (7)  Bath 
County,  Kentucky;  and  (8)  Dodge  County,  Wisconsin.1  Other 
known  occurrences  of  minor  importance  are  indicated  on  the 
map,  Fig.  169,  and  in  addition  the  ore  has  been  recently  discov- 
ered by  drilling  in  Missouri. 

Of  all  these  districts,  the  Birmingham,  Alabama,  one  is  the 
most  important,  with  Chattanooga,  Tennessee,  and  central  New 
York  ranking  respectively  second  and  third. 

1  It  has  been  recently  shown  that  this  area  is  not  of  Clinton  age,  but  is  older  and 
represents  deposition  in  local,  but  connected  basins  of  Maquoketa  (Richmond) 
time  (58a). 


Mines 


PLATE  XLVII.  —  Geologic  map  of  western  half  of  Birmingham,  Ala.,  district. 
(After  Burchard,  Amer.  Inst.  Min.  Engrs.,  Bull.  24,  1908.) 

(538) 


£§^ir^f a  \  (( 

._JHEL_BY__i._CO,_  _.2l \\ 


PLATE  XLVIII.  —  Geologic   map  of  eastern  half  of   Birmingham,    Ala.,   district. 
(After  Burchard,  Amer.  Inst.  Min.  Engrs.,  Bull.  24,  1908.) 

(539) 


540 


ECONOMIC   GEOLOGY 


The  Clinton  ore  deposits  occur  as  beds,  or  lenses,  interstrat- 
ified  with  shales  and  sandstones  at  different  horizons  in  the 
Clinton,  and  as  many  as  three  or  four  beds  may  be  present 
at  any  one  locality.  They  show  extremes  of  thickness,  rang- 


FOSSIL  IRON  ORES 

IN 
T.HE  UNITED  STATES 


FIG.  169.  —  Map  of  eastern  United  States,  showing  areas  of  outcrop  of  Clinton 
iron  ore.1     (After  McCallie,  Ga.  Geol.  Surv.,  Bull.  17.) 


ing  from  a  few  inches  to  40  feet,  but  rarely  exceeding  10  feet. 
The  thicker  beds  often  contain  sandstone  and  shale  partings, 
and  a  single  bed  is  sometimes  traceable  for  miles  along  the 
outcrop. 

The  dip  of  the  beds  depends  on  the  intensity  of  folding  that 
has  occurred    in  any  given  area.     Thus  the  ore  beds  in  New 

1  See  footnote,  page  537. 


IRON   ORES 


541 


LTONj  f3         7N 

, R        ^X*     XXockford  j 


Longitude  West  from  Greenwich 


Areas  containing 
•workable  iron-ore 


Areas  containing  possibly  Areas  probably  containing 

workable  iron-ore  little  or  no  workable  iron-ore 

Scale 
0      5     10      15     20     25     30  miles 


FIG.  170.  —  Map  showing  outcrop  of  Clinton  ore  in  Alabama.     (After  Burchard, 
Amer.  Inst.  Min.  Engrs.,  Bull.  24,  1908.) 


York  State  are  nearly  horizontal,  and  can  at  times  be  mined 
for  some  distance  from  the  outcrop  by  stripping;  while  those 
found  in  the  Appalachian  region  show  a  variable  and  sometimes 


542  ECONOMIC   GEOLOGY 

steep  dip,  and  hence  require  to  be  worked  by  underground 
methods. 

Two  textural  varieties  of  Clinton  ore  are  recognized,  viz.  (1)  fossil 
ore,  and  (2)  oolitic  ore. 

The  former  is  made  up  almost  entirely  of  a  mass  of  fossil  fragments, 
while  the  latter  consists  of  small,  rounded  grains  of  concretionary 
character.  These  two  varieties  may  occur  in  the  same  or  separate 
beds. 


FIG.  171. —  Outcrop  of  Clinton  iron  ore,  Red  Mountain,  near  Birmingham,  Ala. 
(Photo,  from  Tennessee  Coal  and  Iron  Company.) 

A  second  classification,  based  on  grade,  includes  (1)  soft  ore,  and 
(2)  hard  ore.  The  former  is  found  in  the  outcropping  portion  of  the 
seam  and  may  extend  to  variable  depths,  sometimes  as  much  as 
400  feet,  while  the  latter,  which  is  usually  sharply  separated 
from  the  former,  occurs  lower  down.  The  soft  ore  runs  high  in  iron 
and  silica,  but  low  in  lime,  because  this  has  been  removed  by  weath- 
ering. The  hard  ore  runs  high  in  lime,  but  low  in  silica  and  iron. 
Both  varieties  are  high  in  phosphorus  and  hence  of  non-Bessemer 
grade. 

Birmingham,  Alabama  (5l).  —  The  great  development  of  the  Bir- 
mingham district  is  due  to  peculiar  local  conditions^  for  we  find  the 
iron  ores,  flux,  and  fuel  all  in  close  proximity  to  each  other  (Fls. 
XL VII,  XL VIII). 


IRON   ORES 


543 


The  Clinton  ore  beds  are  found  in  Red  Mountain  (Figs.  170, 
171)  on  the  east  side  of  the  valley  in  which  the  city  of  Birming- 
ham lies.  There  the  Clinton  formation,  which  is  200  to  500 
feet  thick  and  dips  southeastward  from  29°  to  50°,  is  composed 
cf  beds  of  shale  and  sandstone  and  includes  four  well-marked 
iron-ore  horizons,  generally  in  the  middle  third  of  the  forma- 
tion. 

These  beds  are  known  as  the  Hickory,  Ida,  Big,  and  Irondale  seams, 
but  there  is  difficulty  in  correlating  them  in  different  parts  of  the  field. 

Of  these  four  beds  the  Big  and  Irondale  are  the  most  important.  The 
thickness  of  the  former  is  estimated  at  from  16  to  30  feet,  but  the  good 
ore  is  rarely  more  than  10-12  feet  thick,  and  at  most  places  only  7  to  10 
feet  are  mined.  In  the  middle  of  the  district,  the  bed  is  separated  into 
two  benches  by  a  parting  along  the  bedding  plane,  or  by  a  shale  bed. 
Either  bench,  though  producing  in  one  part  of  the  district,  may  grade 
into  shaly  low-grade  ore  in  another  part. 

The  following  analyses  are  given  by  Harder  (Min.  Res.  1908),  to  show 
the  gradation  from  hard  ore  to  soft  ore. 


ANALYSES  OF  CLINTON  IRON  ORE  FROM  ALABAMA 


1 

2  " 

3 

4 

Fe  .  --.'••„ 

3700 

45  70 

50  44 

54  70 

SiO->  

7.14 

12.76 

12.10 

13.70 

A1-O3 

381 

4  74 

606 

5  66 

CaO  

19  20 

8.70 

4.65 

.50 

Mn  

23 

19 

21 

.23 

S  .  .  . 

08 

08 

07 

08 

P 

30 

49 

46 

10 

The  unweathered  ore  is  said  by  Burchard  to  range  fi  om  a  richly  ferru- 
ginous sandstone  to  a  ferruginous- siliceous  limestone. 

New  York  (55).  —  In  this  state  the  outcrop  of  the  ore  extends 
across  the  central  and  western  part  of  the  state  (Fig.  172).  The 
whole  formation  dips  gently  southward,  with  a  gentle  north-south 
synclinal  trough  in  Cayuga  and  Wayne  counties.  Both  oolitic  and 
fossiliferous  ore  are  found,  and  at  least  two  beds,  and  sometimes 
four,  may  be  present  at  any  given  locality.  The  ore  varies  in  its 
richness,  and  while  the  deposits  are  very  extensive,  they  have  been 
but  little  developed. 


544 


ECONOMIC   GEOLOGY 


FIG.  172.  —  Map  showing  outcrop  of  Clinton  ore  formation  in  New  York  State. 

(After  Newland.) 

Analyses-  of  Clinton  Ore.  —  The  following  are  analyses  of  the 
Clinton  ore  from  several  localities,  which  serve  more  to  show  its 
variation  in  character,  than  as  types.  Others  are  given  above  under 
Alabama. 


I 

II 

in 

IV 

V 

Fe  

31.3 

31.07 

54.3 

33.341 

57.00 

p 

24 

.69 

.462 

1.2023 

.678 

SiO2 

2398 

856 

15.64 

1.143 

7  12 

TiO2    

.225 

A12O3  

7.26 

5.04 

.89 

5.468 

MnO 

Tr. 

.28 

.154 

CaO    
MgO  

9.15 
2.92 

13.71 
7.37 

1.09 
.13 

16.56  1 
9.974  2 

1.46 

SO3 

987 

072 

C02     
H2O     

9.6 
.26 

18.8 
Undet. 

None 
3.07 

10.865 

— 

s 

.03 

I,  II,  N.  Y.  State  Mus.,  Bull.  123  :  33,   1908.  III.   Ga.  Geol.  Surv., 

Bull.  17 :  130.     IV.   U.  S.  Geol.  Surv.,  Bull.  385.  V.   U.  S.  Geol.  Surv., 
Bull.  285  :  188,  Alleghany  Co.,  Va. 

i  CaC03.  !  MgCOs.  3  P2O6.  *  Mn. 


IRON   ORES 


545 


Origin  of  Clinton  Ore.  —  The  origin  of  this  ore  has  created  con- 
siderable discussion,  and  whatever  theory  is  advanced,  it  must 
explain  the  following  features :  (1)  the  fossiliferous  character  of 
some  beds,  (2)  the  oolitic  character  of  others,  (3)  the  bedded 
structure,  (4)  the  soft  non-calcareous  ore  at  the  surface,  and  the 
hard  or  more  calcareous  ore  at  lower  levels. 

The  three  theories  which  have  been  advanced  are  the  following  : 
(1)  original  deposition,  (2)  residual  enrichment,  (3)  replacement. 
As  can  be  easily  seen,  the  correct  solution  of  the  problem  is  of  practi- 
cal value,  since  it  indicates  the  possible  extent  of  the  ore  body. 

Residual  Enrichment.  —  This  theory  supposes  that  the  ore  beds  rep- 
resent the  weathered  outcrops  of  ferruginous  limestones.  That  is  to  say, 
the  lime  carbonate  was  leached  out  by  surface  waters  down  to  the  water 
level,  leaving  the  insoluble  portion  carrying  the  iron,  in  a  more  concen- 
trated form.  If  this  theory  is  correct,  then  the  ore  should  pass  into  lime- 
stone below  the  water  level. 

Russell  (57),  who  was  an  earnest  advocate  of  this  theory,  noted  that 

at  Attalla,  Alabama,  the 
Clinton  limestone  at  a 
depth  of  250  feet  from  the 
surface  carried  only  7.75 
per  cent  of  iron,  while 
at  the  outcrop  it  had  57 
per  cent  of  iron.  These 
figures  would  seem  to 
bear  out  this  theory,  but 
Eckel  (51)  has  rocently 
claimed  that  they  must 
be  incorrect,  as  the  hard 


FIG.  173.  —  Typical  profile  of  slope  on  Red  Mountain, 
starting  on  the  iron-ore  out-crop.  Shows  bedded 
character  of  ore.  (After  Burchard,  Amer.  Inst. 
Min.  Engrs.,  Bull.  24,  1908.) 


ore  at  the  depth  men- 
tioned above  carries  38 
to  42  per  cent  of  iron. 
Moreover,  in  none  of  the  many  fairly  deep  mines  in  Clinton  ore  has  any 
change  to  limestone  been  noted. 

Sedimentary  Origin.  —  This  supposes  that  the  ores  are  of  contem- 
poraneous origin  with  the  inclosing  rocks,  having  been  deposited  on  the 
sea  bottom  as  chemical  precipitates. 

This  view  was  advocated  at  an  early  date  by  James  Hall,  who  believed 
that  the  iron  came  from  the  old  crystalline  rocks,  which  were  leached  of 
their  iron  content,  the  oolitic  ore  being  a  chemical  precipitate  on  the 
ocean  floor. 

Smyth  (59)  in  amplifying  this  theory  agrees  with  Hall  as  to  the  source  of 
the  ore.  He  points  out  that  during  Clinton  times  the  drainage  from  the  crys- 
talline area  was  carried  into  a  shallow  sea  or  basin.  When  the  iron  was 
carried  into  these  inclosed  basins,  it  was  slowly  oxidized  and  precipitated, 
gathering  layer  upon  layer  about  the  sand  grains,  thus  forming  oolitic  ore. 


546  ECONOMIC   GEOLOGY 

Where  the  ferruginous  waters  came  in  contact  with  shell  fragments 
the  iron  was  precipitated  around  these,  either  due  to  a  reaction  with  the 
carbonate  of  lime  in  the  shells,  or  more  often  by  oxidation.  Later  both 
types  of  deposit  became  covered  by  ordinary  sediments  such  as  shales, 
sandstones,  or  even  limestones. 

Additional  evidence  favoring  a  sedimentary  origin  is  the  continuation 
of  the  ore  with  depth,  some  mines  in  Alabama  being.  2000  feet  from  the 
outcrop.  Moreover  some  borings  in  Alabama  have  struck  the  ore  |  to  1 
mile  from  the  outcrop  and  400  to  800  feet  below  the  surface.  The  occur- 
rence of  fragments  of  ore  in  the  overlying  limestone  also  points  to  the 
ore  being  laid  down  before  the  lime  rock. 

McCallie  (54),  after  studying  the  Georgia  ores,  while  admitting  their 
sedimentary  origin,  believes  that  the  original  iron  mineral  was  greenalite 
or  glauconite. 

Replacement  Theory.  —  This  theory  assumes  that  the  ores  were  of 
much  later  origin  than  the  inclosing  rock,  and  were  formed  by  the  replace- 
ment of  the  lime  carbonate  by  iron,  brought  in  by  percolating  waters, 
which  had  leached  the  ferruginous  constituents  from  the  overlying  strata. 

The  structure  of  the  formations,  the  comparative  absence  of  iron  in 
the  limestone  overlying  the  ore,  and  restricted  vertical  range  of  the  ores 
have  been  advanced  as  arguments  against  this  theory. 

Rutledge  (58),  however,  as  a  result  of  his  studies  of  the  Clinton  ores  of 
Stone  Valley,  Pennsylvania,  concludes  that  they  represent  replacement  de- 
posits, and  that  the  only  part  of  the  iron  content  which  is  of  sedimentary 
character  is  that  contained  in  the  siliceous  concretions,  most  of  the  iron  hav- 
ing come  from  the  shale  overlying  the  ore  beds  ;  the  hematite  deposits  have 
thus  been  formed  by  replacement  of  limestone  and  concentration  of  the 
ore.  The  evidence  presented  in  favor  of  this  view  is:  (1)  the  invariable 
association  of  the  soft,  rich  ore  with  the  leached  decolorized  shales,  and  of 
the  hard,  lean  ores  with  unweathered  bright  shales ;  (2)  the  relations  of 
the  ores  to  the  shattered  sandstones  and  to  the  topographic  situation  of 
the  ores ;  (3)  the  fact  that  analogous  replacements  are  now  taking  place 
in  the  Medina ;  (4)  the  observed  progressive  steps  in  the  transformation 
of  the  limestone  to  an  ore,  which  may  be  followed  in  the  field,  in  thin 
sections,  and  in  chemical  analyses,  and  (5)  the  absence  of  conditions, 
such  as  a  local  crumpling,  including  a  shrinking  of  the  strata,  pointing  to 
a  relative  rather  than  an  absolute  enrichment  of  the  ores. 

In  view  of  the  fact  that  the  advocates  of  the  several  theories  often 
bring  apparently  good  evidence  to  support  their  case,  one  may  perhaps 
question  whether  several  different  methods  of  concentration  have  not 
been  operative.  To  the  author,  it  seems  that  the  sedimentary  mode  of 
accumulation  has  probably  been  the  dominant  one  in  most  cases. 

Canada.  —  Wabana,  Newofundland  (84).  —  The  ores  found 
here  are  of  a  distinctly  bedded  character,  being  part  of  a  series 
of  northwesterly  dipping  Ordovician  sediments  exposed  for  about 
three  miles  along  the  north  shore  of  Bell  Island  in  Conception 
Bay.  The  whole  series  extending  from  Lower  Cambrian  to  Lower 


IRON   ORES 


547 


Ordovician  is  several  thousand  feet  thick,  and  consists  of  un- 
metamorphosed  sandstones  and  shales,  but  in  the  upper  thousand 
feet  there  has  been  a  concentration  of  ferruginous  minerals. 

Within  the  Lower  Ordovician  series,  considered  as  equivalent 
to  the  British  beds  of  Arenig  to  Llandeilo  age,  there  are  six  zones, 
containing  beds  of  shale  and  sandstone  alternating  with  oolitic 
iron  ore,  and  in  one  zone  oolitic  pyrite.  The  iron  ore  is  red  brown, 
massive,  and  breaks  up  readily  into  parallelopiped-shaped  blocks, 
the  breaks  being  marked  by  minute  veinlets  of  calcite  and  quartz. 
Texturally  the  ore  shows  a  number  of  concretions  from  ^V  to  \ 
inch  diameter.  These  spherules  are  composed  of  alternating  con- 
centric layers  of  hematite  and  chamosite,  which  were  pierced  by 
living  boring  algae.  Siderite  is  locally  abundant  and  may  replace 
hematite,  chamosite  or  even  quartz. 

The  ore,  which  is  of  shallow-water  orgin,  and  shows  ripple- 
marked  surfaces,  is  thought  to  represent  a  chemical  precipitate. 

Iron  brought  into  the  sea  from  crystalline  rocks  on  the  land, 
was  precipitated  by  the  oxidizing  action  of  the  algae,  as  ferric 
oxide,  some  of  which  may  have  reacted  with  aluminous  sediment 
to  form  chamosite.  The  siderite  was  possibly  formed  by  am- 
monium carbonate  given  off  as  a  decomposition  product,  below 
the  sediment  surface. 

The  oolitic  pyrite  represents  a  deeper  water  formation,  formed 
presumably  in  the  same  way  as  the  pyrite  nodules  now  originating 
in  the  Black  Sea,  viz.  due  to  the  action  of  hydrogen  sulphide 
liberated  by  bacterial  action,  reacting  with  iron  salts.  The 


ANALYSES  OF  CANADIAN  IRON  ORES 


, 

II 

Ill 

IV 

V 

VI 

VII 

VIII 

Fe     . 

52.58 

47.5 

36.70 

55.77 

31.35 

53.89 

40.36 

59.57 

SiO2 

12.59 

222.7 

45.20 

12.78 

2  46  .  70 

12.52 

12.12 

8.33 

Al2Os 

5.71 



.25 

1.58 

.92 

3.17 

4.33 

1.71 

P 

1  1.63 

.65 

.057 

.107 

.81 

1.032 

1.19 

.057 

S 



.05 

.019 

.074 

.006 

.091 



.137 

CaO 

1.49 

1.06 

3.77 

2.11 

2.07 

15.26 

3.82 

MgO 

.42 



1.59 

3.52 

.31 

.41 



1.05 

MnO 

.06 

31.2 

3    .04 

3    .09 



1.9 



97 

Ignition    loss 

2.17 













1  As  P2O5. 


2  Insoluble. 


Mn. 


I.  Hematite,  Dominion  Bed,  Wabana,  N.  F.;  II.  Bathurst,  N.  B.,  Magnetite;  III. 
Crude  magnetite,  Moose  Mountain,  Ont. ;  IV.  Concentrates,  same  place;  V.  Magnetite 
Nictaux-Torbrook  basin,  N.  S.;  VI.  Hematite,  Leckie  vein,  same  district;  VII.  Hematite^ 
shell  vein,  same  district;  VIII.  Magnetite,  Texada  Island,  B.  C. 


548  ECONOMIC   GEOLOGY 

Wabana  deposits  are  of  great  economic  importance,  the  under- 
ground workings  extending  out  under  the  sea. 

Nictaux-Torbrook  Basin,  Nova  Scotia  (94) .  —  An  interesting 
series  of  bedded  Silurian  ores  is  found  in  this  belt  lying  between 
the  Devonian  granites,  and  the  Triassic  area,  of  southwestern 
Nova  Scotia.  The  ore,  which  is  interbedded  with  shales  and 
sandstones,  dips  steeply,  and  while  it  is  chiefly  hematite,  it  may 
be  locally  changed  to  magnetite.  Other  bedded  hematites  of 
similar  age  occur  at  Arisaig  on  the  north  shore. 

Other  Foreign  Deposits.  —  The  hematite  deposits  of  the  Minas  Geraes 
district  of  Brazil,1  located  some  300  miles  from  the  coast,  are  among  the  largest 
known  iron  deposits  of  the  world.  The  iron  series  includes  clay  slates,  sub- 
ordinate limestone  beds,  and  most  important,  quartzites  (itabirite),  the  last 
ranging  from  a  nearly  pure  quartz  rock  with  scattered  flakes  of  hematite, 
to  massive  quartz-free  hematite.  The  ore  forms  lenses,  often  of  tremendous 
size,  interbedded  with  the  quartzite.  The  following  analyses  show  the  com- 
position of:  (I),  hard  blue  massive  ore,  and  (II)  thin-bedded  ore. 

Fe  P  Si          Mn          Al         CaO       MgO          S  Ign 

I 69.35       .010          .13         .15  .33          tr  .03          .01  .31 

II     .....       63.01      .184       1.79         .16        1.53        .08         .01         .03        6.00 

The  iron-bearing  formation  is  supposed  to  represent  a  sedimentary  series, 
the  iron  having  been  deposited  originally  as  ferric  hydrate,  or  possibly  ferrous 
carbonate.  Subsequent  metamorphism  changed  the  iron  to  crystalline 
herratite,  while  later  surface  weathering  gave  some  detrital  deposits. 

Other  interesting  and  to  some  extent  important  hematite  deposits  are,  the 
replacements  of  hematite  in  limestone  of  Bilbao,  Spain,2  the  contact  meta- 
morphic  deposits  on  the  island  of  Elba,3  the  replacement  deposits  of  Erzberg 
in  Styria,4  and  similarly  formed  hematites  in  Carboniferous  and  Silurian 
limestones  of  Cumberland  and  Lancashire,  Eng.5 

LIMONITE  6 

Limonite  (23,  23a,  62-73) ,  or  brown  hematite,  is,  like  magnetite, 
of  little  importance  in  the  United  States  as  compared  with  hema- 
tite, having  yielded  but  3.7  per  cent  of  the  total  domestic  iron-ore 
production  in  1914,  but  in  other  countries  of  the  world  it  may 
sometimes  be  of  great  commercial  importance. 

1  Leith  and  Harder,  Econ.  Geol.,  VI:    670,  1911;  Derby,  Iron  Ore  Resources  of 
World,  Stockholm,  1910:  817;  Harder,  Econ.  Geoh,  IX:   101,  1914. 

2  Vogt,  Krusch  u.  Beyschlag,  Lagerstatten  II:  319,  1912. 

3  Vogt,  Krusch  u.  Beyschlag,  Ore  Deposits,  Translation  I:   369,  1914. 

4  Vogt,  Krusch  u.  Beyschlag,  II:  311,  1912. 

5  Ibid.  p.  317. 

6  The  name  limonite  is  used  here  in  a  broad  sense  to  include  the  different  hydrous 
iron  oxides. 


IRON   ORES  549 

Limonites  are  rarely  of  high  purity,  mainly  because  of  the  fact 
that  they  are  frequently  associated  with  clayey  or  siliceous  matter, 
but  this  can  sometimes  be  separated  to  a  large  extent  by  washing. 

Types  of  Deposits  (233,  626,  63a).  —  Limonite  ores  may  occur  under  a 
variety  of  conditions,  and  associated  with  different  kinds  of  rocks,  the  more 
important  types  being  as  follows: 

1 .  Residual  deposits,  consisting  of  residual  clay  derived  from  different  kinds 
of  rocks  by  weathering  processes,  through  which  the  limonite  is  scattered  in 
pieces  ranging  from  small  grains  to  large  masses.     The  deposits  are  usually 
siliceous,  except  in  those  of  a  lateritic  character  (Cuba). 

2.  Gossan  deposits,  derived  usually  from  the  weathering  of  suk>hide  ore 
bodies.     These  may  cap  pyrite  masses,  or  sulphides  of  other  metals  (many 
western  ones). 

3.  Replacement  deposits. 

4.  Bedded  deposits,  usually  of  oolitic  character,  and  marine  origin  (Luxem- 
bourg).    Here  the  limonite  may  have  been  precipitated  as  such  on  the  ocean 
bottom,  or  it  was  possibly  precipitated  as  siderite  or  glauconite  and  later 
changed  to  the  ferric  hydroxide. 

5.  Bog-iron  ores,  representing  deposits  of  ferric  hydroxide  precipitated  in 
bogs  or  ponds,  the  iron  having  been  brought  to  the  pond  in  solution.     Fer- 
rous compounds  are  more  easily  soluble  than  ferric  ones,  and  the  iron  may 
go  into  solution  as  sulphate,  as  bicarbonate  in  presence  of  an  excess  of  CO2,  or 
as  soluble  salts  of  organic  acids. 

The  precipitation  may  be  due  to:  1.  Certain  bacteria,  which  deposit  ferric 
hydroxide  in  thejr  cells;  2.  By  oxidation  of  ferrous  carbonate;  3.  By  pre- 
cipitation of  ferrous  carbonate  first  as  such  due  to  loss  of  CO2,  and  presence 
of  organic  matter,  the  carbonate  sometimes  changing  over  later  to  the  hydrox- 
ide. 4.  By  change  of  ferrous  sulphate  to  ferric  hydroxide  in  presence  of  oxy- 
gen, but  the  former  might  react  with  calcium  carbonate,  and  yield  siderite 
with  gypsum;  or  the  sulphide  may  be  derived  from  sulphate  in  presence  of 
decaying  vegetable  matter. 

The  ferric  hydroxide  is  possibly  precipitated  first  in  colloidal  form,  and 
changes  later  to  a  crystalline  condition.  Its  precipitation  in  some  localities 
has  been  sufficiently  rapid  to  permit  gathering  a  supply  from  the  pond  bottom 
every  few  years. 

Distribution  of  Limonite  in  the  United  States  (13,  22a,  62-73).  — 
Although  deposits  of  limonite  are  widely  scattered  over  the  United 
States  (Fig.  174),  about  nine-tenths  of  the  quantity  produced  cones 
from  five  states,  viz.,  Alabama,  Virginia,  Tennessee,  Georgia,  and 
Pennsylvania;  indeed,  the  first  supplied  over  60  per  cent  of  the 
total  output  in  1914. 

Residual  Limonites. — The  residual  limonites  supply  a  large  per- 
centage of  the  domestic  production,  and  have  been  formed  (1)  by 
the  weathering  of  pyritiferous  sulphide  bodies  (see  gossan),  or 
(2)  more  often  by  the  weathering  of  ferruginous  rocks. 


550 


ECONOMIC   GEOLOGY 


B551  Limanite  (Brown  Ore) 
Sider-ite  (Carbonate  Ore) 


FIG.  174.  —  Map  showing  distribution  of  linionite  and  siderite  in  the  United  States. 

(After  Harder.) 

Gossan  deposits  (16,  23a).  —  Limonite  gossan  ores  derived  from 
the  oxidation  of  pyrite,  chalcopyrite,  and  pyrrhotite  deposits 
are  found  at  a  number  of  localities  in  the  crystalline  belt  of 
New  England  and  the  southern  Atlantic  states,  but  they  are  of 
limited  importance  at  the  present  time.  One  belt  of  historic 
and  former  commercial  importance  is  the  "  Great  Gossan 
Lead  ".found  mainly  in  southwestern  Virginia  (23a),  and  trace- 
able for  over  20  miles,  its  contents  averaging  40  to  41  per  cent 


E3 

Brown  ore  deposits      Hematite  deposits     Magnetite  deposits 
I         x7!  I         ^7~\ 

IX  I  I  / I 

Contact  of  crystalline  rocks      Contact  of  crystalline  m 
and  Paleozoic  sediments  and  coastal  plain  deposits 

so  o  so  too  Miles 


^v~kx*L.sg 

cs=i — k_i^^ 


FIG.  175.  —  Map  showing  location  of  iron-ore  deposits  in  Virginia.      (After  Harder, 
U.  S.  GeoL  Surv.,  Bull.  380.) 


PLATE  XLIX 


FIG.  1.  —  Pit  of  residual  limonite,  Shelby,  Ala.     (After  McC  alley,  Ala.  Geol.  Sum., 
Re-pi,  on  Valley  Regions,  Pt.  II.) 


FIG  2.  —  Old  limonite  pit,  Ivanhoe,  Va.,  showing  pinnacled  surface  of  limestone 
which  underlies  the  ore-bearing  clay.  The  level  of  surface  before  mining  began 
is  seen  on  either  side  of  excavation.  (H.  Ries,  photo.) 


(551) 


552 


ECONOMIC   GEOLOGY 


metallic   iron.     (See  also  Ducktown,  Tennessee,  and  Copper  in 
Virginia.) 

Limonite  gossan  ores  are  not  uncommon  in  many  of  the  western 
sulphide  deposits,  and  many  of  them  carry  more  or  less  manganese 


Romnej  Shale 


•''Monterey"  (Oriskany)  sandstone 
Lewistown  limestone 


Clinton  (Rockwood)  formation 

Toscarora-  -\MM8anuttenrClraoh-i 
-  - i  t  Bays  / 


Martinsburg 


liberty  Hall  limestone1)  f  DC 

Cblck.rn.uga    C 
Murat  Limestone J  U 


Oriskanj  brown  ore 
Clinton  fossil  bematHa 


Limestone  aagnetlta 


run    .. 
Natural  Bridge  ••MhMHaBAwMr 

•-Honaker-l 


FIG.  176.  —  Geologic  section  showing  position  of  iron-ore  deposits  in  Virginia. 
(After  Watson,  Min.  Res.  Va.,  1907.) 

oxide,  some,  as  those  at  Leadville,  having  sufficient  to  be  used  in 
the  manufacture  of  spiegeleisen.  Their  main  use,  however,  is  as  a 
flux  in  copper  and  silver  smelting  in  the  western  states.  The  most 
important  ones  are  in  the  Black  Hills,  South  Dakota;  Leadville, 
Colorado;  Neihart,  Monarch,  and  Elkhorn,  Montana;  the  Tintic 
district,  Utah;  Tombstone,  Arizona;  and  Pioche  and  Eureka, 
Nevada. 

Limonites   in  Residual   Clays.  —  The    other    class  of  residual 


IRON   ORES 


553 


limonites  has  many  scattered  representatives,  but  the  most  im- 
portant ones  form  a  belt  extending  from  Vermont  to  Alabama 
(51,  71)  and  divisible  into  two  groups,  viz.,  the  mountain  and 
the  valley  ores.  In  these  the  iron  occurs  as  grains,  lumps,  or 
masses  scattered  through  residual  clays,  associated  'with  Cambro- 
Silurian  limestones,  shales,  and  quartzites. 


' 


g  r  .  \^~^ 


FIG.  177.  —  Vertical  section  showing  the  structure  of  the  valley  brown  ore  deposits 
at  the  Rich  Hill  mine,  near  Reed  Island,  Va.  (After  Harder,  U.  S.  Geol.  Surv., 
Bull.  380.) 

The  mountain  ores  are  located  in  the  eastern  part  of  the  Appala- 
chian limonite  belt,  generally  in  the  Blue  Ridge  or  Appalachian 
Mountains,  or  at  least  near  their  western  edge. 

The  valley  ores  are  closely  associated  with  them  on  the  west,  and 
there  is  no  sharp  line  of  separation  between  the  two.  The  two  t3^pes, 
however,  present  certain  important  differences. 

Thus  the  mountain  ores  usually  form  relatively  small,  discon- 
nected pockets  in  the  residual  material  over  the  Lower  Cambrian 
quartzite,  at  or  near  its  contact  with  the  overlying  formation, 
usually  a  limestone,  while  other  types  of  less  common  occurrence 
are  known.  The  valley  ores,  on  the  other  hand,  form  more  extensive 
though  shallower  deposits  in  residual  clay  overlying  limestones 
(Fig.  177)  above  the  quartzite. 

In  either  case,  however,  the  ore  is  not  uniformly  distributed 
through  the  clay,  so  that  individual  pockets  soon  become  worked  out, 
necessitating  the  finding  of  a  new  one. 

Mountain  ores  may  extend  to  a  depth  of  several  hundred  feet, 
but  the  valley  ores  rarely  exceed  fifty  feet  in  depth,  and  in  neither 
case  do  the  deposits  as  a  rule  exceed  500,000  tons,  the  average  being 


554 


ECONOMIC  GEOLOGY 


FIG.  178.  —  Section  of  fractured  quartzite  from  residual  limonite  deposit,  Pittsville, 
Va.     Iron  oxide  deposited  in  part  between  grains  and  m  part  by  replacement? 

100,000  to  200,000.  The  ore  may  form  from  5  to  20  per  cent  of 
the  clay  and  sand  in  different  deposits  or  different  parts  of  the 
same  deposit.  Limonite  and  gothite  are  the  two  iron-ore  minerals, 
the  higher  grades  carrying  as  much  as  55  per  cent  metallic  iron, 
but  the  average  shipments  run  about  45  per  cent.  The  mountain 
ores  are  usually  poorer  than  the  valley  ones,  and  phosphorus  is 
generally  high  enough  to  make  the  ore  non-Bessemer. 

The  following  tables  show  the  percentage  range  of  the  chief  constituents 
(Harder)  of  I,  mountain  ore,  and  II,  valley  ore:  — 


I 
PEB  CENT 

II 
PER  CENT 

Fe    . 

35.00-50  00 

40.00-56.00 

Si02      

10.00-30  00 

5.00-20.00 

P     

.10-2  20 

.05-     .50 

Mn 

50-10  00 

30-  200 

While  Virginia  (23a)  is  the  main  producer  of  residual  limonites, 
still  Alabama's  output  is  of  importance,  and  some  is  also  obtained 
from  Georgia  (67,  72)  and  Pennsylvania  (69). 

Origin  of  the  Cambro-Silurian  Limonites.  —  Both  the  valley 
and  mountain  ores  are  believed  to  have  been  formed  by  the 
action  of  weathering. 


IRON   ORES 


555 


FIG.  179.  —  Section  illustrating  formation  of  residual  limonite  in  limestone.     (After 
Hopkins,  Geol.  Soc.  Amer.,  Bull.  XI.) 

As  the  shale  and  limestones  overlying  the  Cambrian  quartzite 
weathered,  the  iron  oxide  was  set  free,  either  by  the  decomposition 
of  ferruginous  silicates,  or  of  pyrite  or  siderite  in  the  limestones. 
This  was  then  carried  downward  and  concentrated  first  in  the  resid- 
ual clays  of  the  limestone,  forming  the  valley  ores.  If  weathering 
continued  still  deeper,  the  downward  percolating  iron  solutions 
reached  the  impervious  quartzite,  the  ores  (mountain  type)  becom- 
ing concentrated  in  the  clay  overlying  this,  although  some  was 
deposited  in  crevices  in  the  quartzite. 

Oriskany  Limonites  (23a).  —  These  are  so  called  because  of  their 
association  with  the  Oriskany  sandstone.  To  be  more  exact,  they 
are  found  in  the  Lewistown  (Silurian)  limestone,  under  the 
Monterey  (Oriskany)  sandstone,  or  the  Romney  (Devonian) 

shale.  The  main  pro- 


ducing districts  are 
in  Alleghany  County, 
Virginia,  and  central 
Pennsylvania,  but  local 
deposits  are  found  at 
the  same  horizon  in 
West  Virginia,  Ken- 
tucky, and  Ohio. 

The  deposits  (Fig. 
180)  form  replacements 
in  the  upper  portion 
of  the  Lewistown  lime- 
stone, and  may  extend 
along  the  strike  for  a 
distance  of  several 
miles.  The  thickness 
and  depth  are  variable, 
but  in  some  cases  may 


FIG.  180.  —  Section  of  Oriskany  limonite  deposit. 
(After  Holden,  Min.  Res.  Va.,  1907.) 


556  ECONOMIC   GEOLOGY 

reach  75  feet  and  600  feet  respectively.  The  formations  in  which 
the  ore  occurs  have  been  folded  and  the  Oriskany  removed  from 
the  crests  of  the  folds  by  erosion,  so  that  the  ore  is  found  along 
the  outcrops  on  the  flanks  of  the  ridges. 

The  Oriskany  ore  resembles  the  mountain  ore  in  texture,  grade, 
and  impurities,  but  differs  from  it  in  forming  larger  and  more  con- 
tinous  deposits.  It  grades  into  limestone  with  depth. 

Other  Limonite  Deposits.  —  In  northwestern  Alabama,  western  Ken- 
tucky, and  Tennessee,  limonite  occurs  in  residual  and  sedimentary  clays 
overlying  the  Mississippian  limestone.1  Brown  ore  also  occurs  in  the 
Claiborne  (Tertiary)  formation  of  northeastern  Texas  (Q2b,  65,  70),  and  ad- 
joining parts  of  Louisiana  (62a)  and  Arkansas.  The  ore  forms  horizontal  beds 
of  slight  thickness  but  some  extent.  It  is  of  little  value. 

In  the  Ozark  region  of  Missouri  and  Arkansas  (73),  limonites  are  found 
in  residual  clays  over  Cambrian  limestone,  but  are  of  little  economic 
value. 

Small  deposits  are  known  in  Iowa  (63),  Wisconsin  (62),  Minnesota,  and 
Oregon  (16). 

The  brown  ores  of  the  Appalachian  belt  are  much  used  by  pig  iron  manu- 
facturers because,  owing  to  their  siliceous  character,  they  can  be  mixed  with 
high-grade  Lake  Superior  ores  which  are  deficient  in  silica.  They  are  also 
cheaper,  and  their  mixture  with  other  ores  seems  to  facilitate  the  reduction 
of  the  iron  in  the  furnace. 

The  analyses  on  page  557  give  the  composition  of  limonites 
from  a  number  of  different  localities. 

Canada  (4,  92).  —  Bog  iron  ore  has  been  obtained  from  deposits 
in  the  Three  Rivers  District  of  Quebec,  but  its  importance  is 
decreasing.  Some  of  the  ore  obtained  at  the  Helen  Mine  (p.  534) 
is  quite  strongly  hydra  ted,  but  otherwise  comparatively  little 
limonite  is  mined  in  Canada. 

Other  Foreign  Deposits.  —  Limonite  is  obtained  at  a  number  of  localities 
in  other  countries  (1),  but  only  a  few  need  mentioning. 

The  so-called  minettes  2  of  Lorraine,  Luxembourg,  and  Germany  are  of 
great  importance  to  the  European  iron  industry.  They  represent  great  flat 
lenses  associated  with  shales,  sandstones  and  marls  of  middle  Jurassic  age. 
The  ore,  which  is  chiefly  limonite,  with  some  admixture  of  calcite,  is  low 
grade,  its  iron  content  ranging  from  30  to  40  per  cent.  Other  constituents 
include:  P,  1.3-1.8  per  cent;  SiO2,  7.5-33.6  per  cent;  CaO,  5.3-12.3  per  cent. 

iBurchard,  U.  S.  Geol.  Surv.,  Bull.  315:  154,  1907;  and  Hayes  and  Ulrich, 
Geol.  Atlas  Folio,  95,  1903. 

2  Cayeux,  Minerals  de  fer  oolitique  de  France,  Paris,  1909;  Iron  Ore  Resources 
of  the  World,  Stockholm,  1910. 


IRON   ORES 


557 


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558  ECONOMIC  GEOLOGY 

The  theory  of  their  origin  is  that  the  ore  has  been  precipitated  in  sea  water 
directly  as  limonite,  or  first  as  siderite  or  glauconite  and  then  oxidized. 

Other  oolitic  bedded  deposits  may  carry  chamosite  and  thuringite,  as  those 
of  Thuringia  and  Bohemia,  or  hematite  as  some  European  ones  found  in 
Paleozoic  rocks. 


FIG.  181.  —  Section  of  oolitic  iron  ore  (minette)  from  Luxembourg.      X33. 

Eastern  Cuba  l  contains  three  important  districts  of  residual  iron  ore,  two 
of  these — Moa  and  Mayari  in  Oriente  province,  and  a  third,  San  Felipe  in 
Camaguey  province.  The  ore  is  in  residual  clay  derived  from  serpentine, 
and  shows  a  dark  red,  earthy,  surface  zone  occasionally  containing  shots 
and  lumps  of  solid  brown  ore  and  hematite,  below  which  is  yellowish  or  yellow- 
ish brown  ore  changing  rather  suddenly  to  serpentine.  The  average  depth 
at  Mayari  is  15  feet.  The  analyses  indicate  appreciable  hematite  and  baux- 
ite in  the  upper  zone,  while  farther  down  hydrous  iron  oxides  predominate. 
We  have  here  then  a  case  of  lateritic  alteration. 

Analyses  of  the  surface  ore  I,  and  bottom  layer  II  indicate  the  high  grade 
of  these  ores. 

SiO2       AUOa      Fe2O3     Cr2O3      FeO       NiO        MgO       H^O 

comb. 

I 2.26       14.90     68.75      1.89          .77          .74        11.15 

II  ........        7.54        4.97     64.81      3.66       1.49       2.75       1.50      12.75 

SIDERITE 

United  States.  —  Siderite  (74-78)  is  of  little  importance  in  the  United 
States,  both  on  account  of  the  small  extent  of  the  deposits  (Fig.  174)  and  its 
low  iron  content.  When  of  concretionary  structure  with  clayey  impurities, 
it  is  termed  clay  ironstone,  and  these  concretions  are  common  in  many  shales 
and  clays.  In  some  districts  siderite  forms  beds,  often  several  feet  in  thick- 

1Kemp,  Amer.  Inst.  Min.  Engrs.,  Bull.  98:  129,  1915.  (Has  bibliography.) 
Leith  and  Mead,  Ibid.,  Bull.  103:  1377,  1915;  and  Ibid.,  Trans.,  XLII:  90,  1911. 


IRON   ORES  559 

ness,  but  containing  much  carbonaceous  and  argillaceous  matter,  and  is  known 
as  black  band  ore.  This  is  found  in  many  Carboniferous  shales. 

Iron  carbonate  in  bedded  deposits  is  found  in  the  Carboniferous  rocks 
of  western  Pennsylvania,  northern  West  Virginia,  eastern  Ohio,  and  north- 
eastern Kentucky.  These  ores  were  formerly  the  bases  of  an  important  iron- 
mining  industry,  but  little  is  obtained  now  except  in  southeastern  Ohio  (16). 

Concretions  and  layers  of  iron  carbonate  occur  in  the  Cretaceous  clays 
of  Maryland  (13)  and  were  formerly  mined  somewhat  extensively  in  the 
vicinity  of  Baltimore  and  Washington.  Small  deposits  are  also  known  in 
the  Chickamauga  (Ordovician)  limestone  of  southwestern  Virginia  (23a). 
In  the  western  states  iron  carbonate  nodules  are  found  associated  with 
the  Laramie  (Cretaceous)  formation  in  Colorado  and  northern  New  Mex- 
ico, but  they  possess  no  commercial  value  (16). 

Foreign  Deposits.1  —  Earthy  carbonates,  occurring  as  beds,  form  the  great 
bulk  of  the  British  iron  ore  deposits.  The  most  important  ones  are  those 
found  in  Mesozoic  rocks,  especially  of  the  Yorkshire  district.  Others  of  less 
importance  occur  in  the  Carboniferous.  Considerable  siderite  has  been 
obtained  from  the  Cretaceous  limestones  at  Bilbao,  Spain. 

PYRITE 

Pyrite  is  primarily  used  for  sulphuric  acid,  but  after  driving  off 
the  sulphur,  the  residue  is  sometimes  sold  under  the  name  of 
"  blue  billy  "  and  used  for  iron  manufacture,  being  mixed  with  a 
natural  ore  in  the  desired  proportions. 

Production  of  Iron  Ores.  —  The  iron-ore  mining  industry  in  the 
United  States  has  progressed  with  phenomenal  strides,  and  this 
country  now  leads  the  world  in  the  production  of  iron  ore.  Indeed 
so  great  has  the  production  become  that  in  1903  it  was  equal  to  the 
combined  output  of  Germany  and  Luxemburg  and  the  British 
Empire  for  1902.  Moreover,  the  average  iron  content  of  the  ore 
mined  in  the  United  States  is  higher  than  that  mined  in  foreign 
countries,  thereby  resulting  in  the  production  of  a  greater  amount  of 
pig  iron  from  a  given  quantity  of  ore. 

The  phenomenal  growth  of  the  iron-mining  industry  is  shown  in 
the  following  table:  — 


DECADE 

QUANTITY 

PERCENTAGE  OF 
INCREASE 

1870-1879 

Long  tans 

43  770  527 

1880-1889       

91  043  854 

108.0 

1890-1899       
1900-1909  i 

163,989,193 
2  392  000  000 

80.1 
1380 

Iron  Ore  Resources  of  the  World,  Stockholm,  1910.  2  Approximate. 


560 


ECONOMIC   GEOLOGY 


1870   1875    1880   1885 
65,000,000  P 


1913 
1900    1905    1910   J  1915 


60,000,000 


55,000,000. 


50,000,000 


45,000,000 


35,000,000 
30,000,000 
25,000,000 
20,000,000 
15,000,000 
10,000,000 
5,000,000 


"\7 


" 


v- 


1870   1875    1880    1885    1890    1895    1900    1905    1910  1 1915 

1913 

FIG.  182.  —  Diagram  showing  the  production  of  iron  ore,  pig  iron,  and  bteel  in  the 
United  States,  1870  to  1913.     (U.  S.  Geol.  Surv.  Min.  Res.,  1913.) 

The  Lake  Superior  region  is  now  producing  at  least  three  quarters 
of  the  iron  ore  used  in  the  United  States,  and  it  has  large  reserves 
of  ore,  although  the  high-grade  ones  are  becoming  rapidly  ex- 
hausted. The  low-grade  ores  of  this  region  and  others  will,  how- 
ever, be  available  for  a  much  longer  time. 

While  there  is  not  danger  of  the  present  supply  of  ore  soon  becom- 
ing exhausted,  still,  with  the  present  consumption,  it  is  well  to  con- 
sider possible  sources  of  the  future. 


IRON   ORES 


561 


In  the  United  States  the  Utah  and  some  other  western  deposits 
will  no  doubt  be  drawn  upon,  and  many  ores  now  looked  upon  as  too 
low  grade  to  work  will  also  be  considered.  Aside  from  domestic 
sources  of  supply  there  are  foreign  ones  which  may  perhaps  be  even- 
tually turned  to,  such  as  those  from  Canada,  Newfoundland,  and 
Brazil  on  this  side  of  the  Atlantic,  or  even  those  of  Scandinavia  on 
the  European  side.  Cuba,  even  now  is  sending  considerable  ore 
to  the  United  States. 

PRODUCTION  OF  IRON  ORES  IN  THE  UNITED  STATES  FROM  1909-1914,  BY 
VARIETIES,  IN  LONG  TONS 


1909 

1910 

1911 

1912 

1913 

1914 

Hematite 
Brown  ore     . 
Magnetite     . 
Carbonate     . 

Total  >  .     . 

46,208,640 
i  2,839,265 
12,229,839 
16,257 

51,367,007 
i  2,993,744 
1  3,631,  835 
22,320 

39,626,224 
2,032,094 
2,202,527 
15,707 

51,345,782 
1,614,486 
2,179,533 
10,346 

57,933,251 
1,682,063 
2,357,274 
7,849 

38,286,670 
1,537,750 
1,610,203 
5,138 

51,294,271 

57,014,906 

43,876,552 

55,150,147 

61,980,437 

41,439,761 

1  Some  brown  ores  are  included  in  magnetite. 

PRODUCTION  OF  IRON  ORE  IN  THE  MORE  IMPORTANT  STATES,  1910-1911 


STATE 

1910 

1911 

LONG  TONS 

VALUE 

LONG  TONS 

VALUE 

31,966,769 
13,303,906 
4,801,275 
1,287,209 
1,149,551 
903,377 

861,850 
739,799 
732,247 
521,832 
313,878 

$78,462,560 
41,393,585 
6,083,722 
3,848,683 
3,610,349 
1,845,144 

877,223 
911,847 
1,048,328 
1,582,213 
482,659 

23,398,406 
8,945,103 
3,995,582 
1,057,984 
610,871 
559,763 

0) 
514,929 
469,728 
359,721 
207,279 

$48,447,760 
23,810,710 
4,876,106 
2,959,009 
1,146,188 
1,386,616 

0) 

539,553 
632,339 
1,158,271 
315,704 

Michigan       

Alabama        

Wisconsin      

Virginia    
California,  Colorado,  New  Mex- 
ico, Washington  and  Wyoming 

Tennessee      

New  Jersey  

1911  production  given  only  with  a  large  group  of  states. 

PRODUCTION  OF  IRON  ORE  IN  THE  MORE  IMPORTANT  STATES,  1912-1914  1 


1912 

1913 

1914 

LONG  TONS 

VALUE 

LONG  TONS 

VALUE 

LONG  TONS 

VALUE 

Minnesota    . 

34,249,813 

$61,805,017 

36,603,331  $80,789,025 

23,298,547 

$40,628,771 

Michigan 

12,797,468 

29,003,163 

12,668,560 

33,479,954 

8,533,280 

18,722,358 

New  York     . 

1,167,405 

2,933,024 

1,420,889 

3,100,235 

640,252 

1,992,892 

Alabama 

4,776,545 

5,734,371 

5,333,218 

6,648,569 

4,514,926 

5,727,619 

Wisconsin 

1,152,250 

2,731,574 

896,243 

2,149,397 

591,595 

1,178,610 

Virginia    . 

412,520 

903,130 

492,649 

983,279 

346,382 

719,415 

Pennsylvania 

522,172 

481,353 

478,693 

589,038 

400,062 

399,639 

Tennessee 

416,885 

564,443 

364,092 

493,556 

330,214 

466,523 

New  Jersey  . 

366,823 

1,192,816 

291,653 

980,303 

346,820 

1,076,208 

Georgia    . 

135,337 

227,282 

153,336 

237,876 

66,222 

119,363 

1  Figures  for  1913  and  1914  refer  to  quantity  marketed. 


562 


ECONOMIC   GEOLOGY 


PRODUCTION  OF  LAKE  SUPERIOR  IRON  ORE  BY  RANGES,  1904-1914,  IN  LONG 

TONS 


YEAK 

MAR- 

QUETTE 

ME- 

NOMINEE 

Go- 

GEBIC 

VER- 
MILION 

MESABI 

CUYUNA 

TOTAL 

1904 

2  465  448 

2  871   1  3O 

1905 

3,772,645 

4,472,630 

3,344,551 

1,578,6.'6 

20,156,566 

. 

33,325,018 

1906 
1907 
1908 
1909 

4,070,914 
4,167,810 
3,309,917 
4  291  967 

4,962,357 
4,779,592 
2,904,011 
4  789  362 

3,484,023 
3,609,519 
3,241,931 
3  807  157 

1,794,186 
1,724,217 
927,206 
1  097  444 

23,564,891 
27,245,441 
17,725,014 
°7  877  705 



37,876,371 
41,526,579 
28,108,079 
41  863  635 

1910 
1911 
1912 
1913 
1914 

4,631,427 
3,743,145 
3,545,012 
3,977,808 
3,320,763 

4,983,729 
4,062,778 
4,465,466 
4,997,246 
3,671,499 

4,746,818 
3,099,197 
3,926,632 
4,743,515 
4,601,240 

1,390,360 
1,336,938 
1,457,273 
1,536,115 
1,362,416 

30,576,409 
23,126,943 
32,604,756 
36,378,671 
19,808,434 

181,224 
369,739 
744,007 
776,051 

46,328,743 
35,550,225 
46,368,878 
52,377,362 
33,540,403 

TWELVE  IRON  MINES  OF  THE  UNITED  STATES  WHICH  PRODUCED  THE  LARGEST 
TONNAGE  IN  1914  l 


NAME  OF  MINE 

STATE 

NEAREST 
TOWN 

VARIETY  OF 
ORE 

QUANTITY 
MINED  IN 
1914 

Red  Mountain  group  (3) 

Alabama 

Bessemer 

Hematite 

2,008,465 

Mahoning  (7)      .      . 
Sauntry-Alpena  (4)           .      • 

Minnesota 

Hibbing 
Virginia 

1,212,287 
1,156,150 

Canisteo  (12)       .      . 

1  ' 

Coleraine 

1,051,895 

Leonard  (2)    ... 

" 

Chisholm 

1,022,490 

Norrie  group  (10)    .           . 

Michigan 

Ironwood 

991,291 

Newport  (11)      .. 

1  ' 

-*-*  \    . 

950,243 

Uno  (5)       

Minnesota 

Hibbing 

947,502 

Susquehanna  (14)    . 

•  * 

*  * 

906,913 

Woodward,  1,  2  and  3  (24) 

Alabama 

Lipscomb 

650,507 

Shenango  (16)     .... 

Minnesota 

Chisholm 

619,569 

Leetonia  (26)      .... 

Hibbing 

592,940 

1  The  numbers  in  parentheses  after  the  names  give  the  rank  of  these  same  mines  in  1913. 

IMPORTS  AND  EXPORTS  OF  IRON  ORE  INTO  AND  FROM  THE  UNITED  STATES, 

1912-1914 


IMPORTS 

EXPORTS 

LONG  TONS 

VALUE 

LONG  TONS 

VALUE 

1912        

2,104,576 
2,594,770 
1,350,588 

$6,499,690 
8,336,819 
4,483,832 

1,195,742 
1,042,151 
551,618 

$3,537,289 
3,513,419 
1,794,193 

1913        
1914 

PRODUCTION  OF  IRON  ORE  IN  CANADA  BY  PROVINCES,  1912-1914 


PROVINCE 

1912 

1913 

1914 

TONS 

VALUE 

TONS 

VALUE 

TONS 

VALUE 

New  Brunswick 
Nova  Scotia      . 
Quebec    . 
Ontario    . 

Total     .     . 

71,520 
30,857 
1,185 
112,321 

$127,716 
168,877 
4,232 
222,490 

86,416 
20,436 
5,102 
195,680 

$153,820 
21,049 
26,99"9 
427,975 

4,725 

$10,841 

240,029 

531,200 

215,883 

$523,315 

307,634 

$629,843 

244,754 

$542,041 

Shipments   of  iron  ore  from  Wabana  mines,  Newfoundland, 
were:    1913,  1,605,220  short  tons;   1914,  639,430  short  tons. 


IRON  ORES  563 

EXPORTS  AND  IMPORTS  OF  IRON  ORE  IN  CANADA 


1914 

135  451  tons 

$  360  974 

Imports  

1914 

1,147,108  short  tons 

2,387,358 

PRODUCTION  OF  IRON  ORE  IN  PRINCIPAL  COUNTRIES,  IN  LONG  TONS 


COUNTRY 

LONG  TONS 

COUNTRY 

LONG  TONS 

Canada  (1914)     .... 
Cuba  (1913)    
Newfoundland  (1912)   .      . 
United  States  (1914)     .      . 
Austria-Hungary  (1913)    . 
Belgium  (1912)    .... 

218,620 
1,582,431 
1,251,968 
41,439,761 
5,018,109 
164,734 

Norway  (1913)      . 
Spain  (1913)     
Sweden  (1913)       .... 
United  Kingdom  (1913)      . 
China  (1913)    .      .      . 
India  (1912)     

77,693 
9,706,366 
7,357,845 
15,997,328 
269,748 
580,029 

France  (1913)       .... 
German   Empire   and    Lux- 
embourg (1913)     .    jf/  9  '; 
Greece  (1913)       .... 

21,572,835 

26,771,598 
305,195 

Chosen  (Korea)  (1912) 

Algeria  (1912) 
Tunis  (1912) 

121,224 

1,171,252 
470  866 

Italy  (1913) 

593,618 

Australia  (1912) 

113  989 

1  Russia        

1  Russia  produced  4,131,890  long  tons  of  pig  iron  in  1912 

Iron-ore  Reserves  (3). — As  a  result  of  the  recent  agitation  over  the 
conservation  of  our  mineral  resources,  attempts  have  been  made  by  the 
United  States  Geological  Survey  to  estimate  the  quantity  of  both  at  present 
available  and  non-available  ore  still  remaining  in  the  ground.  That  such 
estimates  can  only  be  very  approximate  is  self-evident,  partly  because  the 
irregularity  of  most  iron-ore  deposits  makes  it  difficult  to  estimate  their 
contents.  Bedded  ores  like  those  of  the  Clinton  can  be  most  closely 
figured  on,  while  in  the  case  of  the  Adirondack  ores  there  may  be  an  error 
of  15  to  20  per  cent. 

The  estimate  of  availability  is  influenced  by  the  cost  of  ore  delivered  at 
furnace,  cost  of  reduction,  and  accessibility;  and  any  of  these  factors  might 
change  at  no  distant  future. 

The  metallic  iron  content  of  ores  now  used  ranges  from  about  30  to  65 
per  cent,  this  wide  variation  being  due  in  part  to  character  of  other  ele- 
ments in  the  ore,  and  in  part  to  favorable  location.  Thus  the  Clinton  ores, 
running  as  low  as  30  per  cent  iron,  can  be  used,  because  their  high  lime 
content  makes  them  practically  self -fluxing,  but  they  must  be  used  near  the 
point  of  production. 

Siliceous  ores  running  under  40  per  cent  iron  are  not  at  present  avail- 
able unless  located  near  fuel  supplies,  because  they  will  not  bear-  the  cost 
of  transportation  and  are  expensive  to  reduce. 

So,  too,  the  amount  of  other  constituents  present,  such  as  phosphorus, 
sulphur,  copper,  chromium,  manganese,  and  alumina,  exert  a  determining 
influence  on  the  cost  of  production  and  quality  of  the  iron. 

Two  tendencies  are  noticeable  in  the  iron  industry  of  the  present  day, 
viz.,  the  use  of  ores  with  a  lower  average  iron  content,  and  the  decentraliza- 
tion of  the  iron  industry. 

This  involves  a  corresponding  increase  in  the  cost  of  transportation  per 
unit  of  iron,  and  an  increase  in  the  proportion  of  fuel  which  goes  to  the  ore- 


564 


ECONOMIC   GEOLOGY 


producing  region.  An  accompaniment  of  this  will  he  the  general  adoption  of 
by-product  coking,  and  Hayes  points  out  that  in  certain  furnaces  now  oper- 
ating in  the  Lake  Superior  district  the  profit  corresponds  approximately  to 
the  value  of  the  by-products  from  the  coke  ovens. 

The  following  table  gives  in  condensed  form  the  figures  compiled  by  a 
committee  of  the  International  Geological  Congress  (1).  They  are,  because 
of  the  difficulties  involved  in  making  estimates,  to  be  regarded  as  only  approx- 
imate, but  they  show  enormous  reserves  nevertheless. 


COUNTRY 

VARIETY  OF  ORE 

ACTUAL 
ORE  SUP- 
PLIES. 
MILLION 
TONS 

EQUIVA- 
LENT ME- 
TALLIC 
[RON.  MIL- 
LION TONS 

POTENTIAL 
ORE  SUP- 
PLIES, 
MILLION 
TONS 

EQUIVA- 
LENT ME- 
TALLIC 
[RON.  MIL- 
LION TONS 

United  States 
Eastern  region 
Clinton 
Ohio   and    other 
states       .     . 
Other      deposits 
Lake  Sup.  reg.    . 
Mississippi  Valley 
Cordilleran     . 
Adirondack,  etc.  . 

Canada 
Newfoundland   . 
Mexico 
Central  America 
Cuba    .... 

R    

C    .     .     .     .. 
R.  L.  M.       . 
R.  L    .     .     . 
R.  L.   .     .     . 
M.  H.       .     . 
T 

505.3 

204.5 
3,500.0 
45.0 
3.0 

187 

95.4 
2,000.0 
21.0 
1.2 

1,368.0 

308.0 
265.5 
72,000.0 
830.0 
115.8 
218.0 

481 

90 
119 
36,000 
382 
50 
100 

M.  H.  C.      . 
R.  T.  C.  S.  . 
M.       ... 
M.        ... 
H.  M.  L.       . 
M.  H.  L.  C.  S. 
H.  M.T.  L.  C. 
M.  H.  L.  S.  . 
H.  L.  M.C.  T. 
H.  M.  B.  L.C.  T. 

4,257.8 
Consi 
3,635.0 
55.0 

2,304.6 
derable 
1,961.0 
30.0 

75,105.3 
Very 

? 
1,007.0 
5,710.0  + 
41,028.7  + 
457.0  + 
Very 
68.6  + 

37,222 
great 

? 

454 
3,055  + 
12,084.6  + 

282.8  + 
high 
37.1  + 

1,903.0 
4.2 
12,031.9 
260.4 
125.0 
135.9 

856.8 
2.0 
4,732.8 
155.5 
75.0 
73.8 

South  America  . 
Europe      .     .     . 
Asia      .... 
Africa  .... 
Australia 

22,408.2 

10,189.5 

Enormou 

s 

R,  red  hematite;    H,  hematite;    L,  brown  ore;    C,  carbonate  and  clay  iron  stone;    M, 
magnetite;   T,  titaniferous  magnetite;   S,  titaniferous  iron  sand;   B,  bog  ore. 


REFERENCES    ON   IRON  ORES 

GENERAL.  1.  Iron  Resources  of  the  World,  Internat.  Geol.  Congress,  Stock- 
holm, 1910.  2.  Allen,  Min.  and  Sci.  Pr.,  Sept.  30,  1911.  (Genesis  iron 
sulphides.)  3.  Birkenbine,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVII: 
519,  1897.  (Iron  ore  supply.)  4.  Eckel,  Iron  Ores,  Occurrence,  Valua- 
tion and  Control,  1914.  (New  York.)  5.  Hayes,  U.  S.  Geol.  Surv., 
Bull.  394:  70,  1909.  (Iron  ore  supply.)  6.  Kimball,  Amer.  Geol., 
XXI:  155,  1898.  (Concentration  by  weathering.)  7.  Leith,  Econ. 
Geol.,  I:  360,  1906.  (Iron  ore  reserves.)  8.  Leith,  Amer.  Inst.  Min. 
Engrs.,  Bull.  110:  227,  1916.  (Conservation.)  9.  Penrose,  Jour. 
Geol.,  I:  356,  1893.  (Chemical  relations  of  iron  and  manganese.) 
10.  Winchell,  Amer.  Geol.,  X:  277,  1892.  (Theories  of  origin.) 

STATE  REPORTS  OF  GENERAL  CHARACTER.  11.  Bayley,  N.  J.  Geol.  Surv. 
Fin.  Rep.,  VII,  1910.  (N.  J.)  12.  Chauvenet,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XVIII:  266,  1890.  (Colo.)  13.  Singewald,  Md.  Geol. 
Surv.,  IX:  121,  1911.  (Md.)  14.  Crane,  Mo.  Bur.  Geol.  Mines, 
2d  ser.,  X,  1912.  (Mo.)  15.  Grimsley,  W.  Va.  Geol.  Surv.,  IV:  1,  1909. 


IRON   ORES  565 

(W.  Va.)  16.  Harder,  U.  S.  Geol.  Surv.  Min.  Res.,  1908,  I:  61,  1909. 
(Brief  resume"  U.  S.  and  bibliography.)  17.  Hice,  Top.  and  Geol.  Com. 
Pa.,  Rep.  9:  71,  1913.  (Pa.)  17a.  Lowe,  Miss.  Geol.  Surv.,  Bull.  10, 
1914.  (Miss.)  18.  McCreath,  Sec.  Pa.  Geol.  Surv.,  MM:  229,  1879. 
(Many  analyses.)  19.  Nitze,  N.  Ca.  Geol.  Surv.,  Bull.  1,  1893.  (N. 
Ca.)  20.  Orton,  O.  Geol.  Surv.,  V:  371,  1884.  (Ohio.)  21.  Shaler, 
Ky.  Geol.  Surv.,  New  Ser.,  Ill:  163,  1877.  22.  Shannon,  Ind.  Dept. 
Geol.  Nat.  Res.,  31st  Ann.  Rept.;  299,  1907.  (Ind.)  23.  Smock,  N.  Y. 
State  Mus.,  Bull.  7,  1889.  (N.  Y.)  23a.  Watson  and  Holden,  Min. 
Res.  Va.,  1907:  402.  (Va.) 

Magnetite.  24.  Ball,  U.  S.  Geol.  Surv.,  Bull.  315:  206,  1907.  (Iron  Mtn., 
Wyo.),  24a.  Bayley,  N.  J.  Geol.  Surv.,  Fin.  Rep.,  VII,  1910.  (N.  J.) 
25.  D'Invilliers,  Sec.  Pa.  Geol.  Surv.,  D  3,  II,  Pt.  I:  237,  1883.  (Berks 
Co.)  25«.  Graton,  U.  S.  Geol.  Surv.,  Prof.  Pap.  68:  313,  1910.  (Fierro, 
N.  M.)  256.  Harder,  Econ.  Geol.,  V:  599,  1910.  (York  Co.,  Pa.) 
25c.  Harder  and  Rich,  U.  S.  Geol.  Surv.,  Bull.  430:  228,  1910.  (Dale, 
Calif.)  25d.  Harder,  U.  S.  Geol.  Surv.,  Bull.  430:  240,  1910.  (Dayton, 
Nev.)  26.  Keith,  U.  S.  Geol.  Surv.,  Bull.  213:  243,  1903.  (N.  C.) 
27.  Kemp,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVIII:  146,1898.  (Mine- 
ville,  N.  Y.)  28.  Kemp,  U.  S.  Geol.  Surv.,  19th  Ann.  Rept.,  Ill:  377, 
1899.  (Adirondack  titaniferous  ores.)  28a.  Kemp,  N.  Y.  State  Mus., 
Bull.  149,  1911.  (Comparison  pre-Camb.,  N.  Y.  and  Swe.)  29.  Leith 
and  Harder,  U.  S.  Geol.  Surv.,  Bull.  338,  1908.  (Iron  Springs,  Utah.) 
30.  Newland  and  Kemp,  N.  Y.  State  Mus.,  Bull.  119,  1908.  (Adiron- 
dacks.)  31.  Paige,  U.  S.  Geol.  Surv.,  Bull.  380,  1909.  (Hanover, 
N.  Mex.)  31a.  Paige,  U.  S.  Geol.  Surv.,  Bull.  450,  1911.  (Llano- 
Burnet  region.)  32.  Prescott,  Econ.  Geol.,  Ill:  465,  1908.  (Heroult, 
Calif.)  33.  Prime,  Sec.  Pa.  Geol.  Surv.,  I:  19C,  1883.  (Lehigh  Co.) 
33a.  Singewald,  U.  S.  Bur.  Mines,  Bull.  64,  1913.  Econ.  Geol.,  VIII: 
207,  1913.  (Titaniferous  magnetites.)  336.  Singewald,  Econ.  Geol., 
VII:  560,  1912.  (Cebolla  dist.,  Colo.)  34.  Spencer,  Min.  Mag.,  X: 
377,  1904.  (Origin  Sussex  Co.,  N.  J.,  magnetite.)  35.  Spencer,  U.  S. 
Geol.  Surv.,  Bull.  359,  1908.  (Cornwall.)  36.  Spencer,  U.  S.  Geol. 
Surv.,  Bull.  315:  185,  1907.  (Berks  and  Lebanon  Cos.,  Pa.)  36a. 
Stebinger,  U.  S.  Geol.  Surv.,  Bull.  430:  329,  1914.  (Titaniferous 
magnetite  sandstones,  Mont.)  37.  Stewart,  Sch.  of  M.  Quart.,  April, 
1908.  (Putnam  Co.,  N.  Y.)  38.  Wolff,  N.  J.  Geol.  Surv,,  Ann.  Rept. 
1893:  359,  1894.  (N.  J.) 

Like  Superior  District.  39.  Bayley,  U.  S.  Geol.  Surv.,  Mon.  XL VI,  1904. 
(Menominee.)  40.  Clements,  U.  S.  Geol.  Surv.,  Mon.  XLV:  1903. 
(Vermilion.)  41.  Clements,  Smyth,  Bayley,  and  Van  Hise,  U.  S. 
Geol.  Surv.,  19th  Ann.  Rept.,  Ill:  1,  1898,  and  Ibid.,  Mon.  XXXVI, 
1899.  (Crystal  Falls.)  42.  Irving  and  Van  Hise,  U.  S.  Geol.  Surv., 
10th  Ann.  Rept.,  I:  341,  1889.  (Penokee.)  43.  Lane,  Can.  Min. 
Inst.,  XII.  (Mine  waters.)  44.  Leith,  U.  S.  Geol.  Surv.,  Mon.  XLIII, 
1903.  (Mesabi.)  45.  Leith,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXV: 
454,  1904.  (Summary  L.  Superior  Geology.)  46.  Leith,  Econ.  Geol., 
II:  145,  1907.  (Cuyuna.)  47.  Van  Hise  and  Leith,  U.  S.  Geol.  Surv., 
Mon.  LII,  1911.  (General.)  48.  Van  Hise,  Bayley  and  Smyth,  U.  S. 


566  ECONOMIC  GEOLOGY 

Geol.  Surv.,  Mon.  XXVIII,  1897.  (Marquette.)  49.  Weidman.  Wis. 
Geol.  and  Nat.  Hist.  Surv.,  Bull.  13,  1904.  (Baraboo.) 

Clinton  Ore.  50.  Burchard,  Tenn.  Geol.  Surv.,  Bull  16,  1913.  (E.  Tenn.) 
51.  Burchard,  Butts,  and  Eckel,  U.  S.  Geol.  Surv.,  Bull.  400,  1909. 
(Birmingham,  Ala.)  51a.  Butts,  U.  S.  Geol.  Surv.,  Bull.  470:  215,  1911. 
(Montevallo-Columbiana  reg.,  Ala.)  52.  Chambeiiin,  Geology  of  Wis- 
consin, II:  327.  (Wis.)  53.  Kindle,  U.  S.  Geol.  Surv.,  Bull.  285: 
180,  1906.  (Bath  Co.,  Ky.)  54.  McCallie,  Ga.  Geol.  Surv.,  Bull. 
17,  1908.  (Ga.)  55.  Newland  and  Hartnagel,  N.  Y.  State  Mus., 
Bull.  123,  1908.  (N.  Y.)  56.  Phalen,  Econ.  Geol.,  I:  660,  1906. 
(N.  E.  Ky.)  57.  Russell,  U.  S.  Geol.  Surv.,  Bull.  52:  22,  1889.  (Resid- 
ual theory  of  origin.)  58.  Rutledge,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXXIX:  1057,  1908.  (Stone  Valley,  Pa.)  58a.  Savage  and  Ross, 
Amer.  Jour.  Sci.,  XLI:  187,  1916.  (s.  e.  Wis.)  59.  Smyth,  Amer. 
Jour.  Sci.,  XLIII:  487,  1892.  (Origin.)  59a.  Thwaites,  U.  S.  Geol. 
Surv.,  Bull.  540:  338,  1914.  (s.  e.  Wis.) 

Hematites  (other  than  Clinton  and  L.  Superior).  60.  Ball,  U.  S.  Geol., 
Surv.,  Bull.  315:  190,  1907.  (Hartville,  Wyo.)  60a.  Harder,  U.  S. 
Geol.  Surv.,  Bull.  503,  1912.  (Eagle  Mts.,  Calif.)  606.  Jones,  Econ. 
Geol.,  VIII:  247,  1913.  (Palisade,  Nev.)  61.  Winslow,  Haworth, 
and  Nason,  Mo.  Geol.  Surv.,  IX,  Ft.  3,  1896.  Also  Ref.  14.  (Iron 
Mtn.,  Mo.)  61a.  Watson  and  Holden,  Min.  Res.  Va.,  1907.  (Va.) 

Limonite.  62.  Allen,  Eleventh  Report  Mich.  Acad.  Sci.,  1909:  95.  (Spring 
Valley,  Wis.)  62a.  Burchard,  U.  S.  Geol.  Surv.,  Bull.  620-G,  1915. 
(n.  La.)  626.  Burchard,  U.  S.  Geol.  Surv.,  Bull.  620-E,  1915.  (n.  e. 
Tex.)  63.  Calvin,  la.  Geol.  Surv.,  IV:  97,  1895.  (la.)  63a.  Dake, 
Amer.  Inst.  Min.  Engrs.,  Bull.  103:  1429,  1915.  (Formation  and  dis- 
tribution, bog  ores.)  636.  Diller,  U.  S.  Geol.  Surv.,  Bull.  213:  219,  1903. 
(Redding,  quadrangle.)  64.  Eckel,  Eng.  and  Min.  Jour.,  LXXVIII: 
432,  1904.  (e.  N.  Y.  and  W.  New  Eng.)  65.  Eckel,  U.  S.  Geol.  Surv., 
Bull.  260:  348,  1905.  (Tex.)  66.  Garrison,  Eng.  and  Min.  Jour., 
LXXIII:  258,  1904.  (Chemical  characteristics.)  66a.  Gordon  and 
Jarvis,  Tenn.  Geol.  Surv.,  Res.  Tenn.,  II,  No.  12:  458,  1912.  (E.  Tenn.) 
67.  Hayes,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXX:  403,  1901.  (Car- 
tersville,  Ga.)  68.  Hobbs,  Econ.  Geol.  II:  153,  1907.  (Conn.,  N.  Y., 
Mass.)  69.  Hopkins,  Geol.  Soc.  Amer.,  Bull.  11 :  475,  1900.  (Pa. 
Cambro-Silurian  ores.)  69o.  Jarvis,  Tenn.  Geol.  Surv.,  Res.  Tenn., 
II,  No.  9.  (Valley  and  mountain  ores.)  70.  Kennedy,  Amer.  Inst. 
Min.  Engrs.,  Trans.  XXIV,  258,  1894.  (E.  Tex.)  71.  McCalley,  Ala. 
Geol.  Surv.,  Rept.  on  Valley  Region,  II,  1897.  (Ala.)  72.  McCallie. 
Ga.  Geol.  Surv.,  Bull.  10,  1900.  (Ga.)  73.  Penrose,  Geol.  Soc.  Amer., 
Bull.  Ill:  47,  1892.  (Ark.  and  Tex.  Tertiary  ores.)  73o.  Weld,  Econ. 
Geol.,  X:  399,  1915.  (Oriskany  ores,  Va.) 

Siderite.  74.  Lowe,  Miss.  Geol.  Surv.,  Bull.,  1912.  (Miss.)  74a.  Moore3 
Ky.  Geol.  Surv.,  2d  ser.,  I,  Pt.  3:  63,  1876.  (Ky.)  75.  Orton,  Ohio 
Geol.  Surv.,  V:  378,  1884.  (Ohio.)  76.  Second  Pa.  Geol.  Surv.,  K: 
386,  and  MM:  159,  1879.  (Pa.)  77.  Raymond,  Amer.  Inst.  Min. 
Engrs.,  Trans.  IV:  339,  1876.  (N.  Y.)  78.  Smock,  N.  Y.  State  Mu- 
seum, Bull.  7:  62,  1889.  (N.  Y.) 


IRON   ORES  567 

Canada.     79.  Bell,  Ont.  Bur.  Mines,  XIV,  Pt.  1:  278,  1905.     (Michipicoten.) 

80.  Coleman   and   Willmott,    Ibid.,    XI:     152,    1902.     (Michipicoten.) 

81.  Coleman  and  Moore,    Ibid.,   XVII:    136,    1908.     (Ranges   east   of 
L.    Nipigon.)      Coleman,    Econ.    Geol.    I:    521,    1906.     (Helen    lion 
Mine.)     82.  Coleman,  Ibid.,  XVIII,  Pt.  I:   151,   1909.     (Nipigon  dis- 
trict.)    83.  Hardman,  Can.  Min.  Inst.,  XI:    156,  1908.     (New  Bruns- 
wick.)    84.  Hayes,  Can.  Geol.  Surv.,  Mem.  78,  1915.     (Wabana,  N.  F.) 
85.  Willmott,  Can.   Min.  Inst.,  XI:    106,    1908.     (Titaniferous.)     86. 
Lindeman,    Mines   Branch,    No.    105,    1913.     (Bathurst,    N.    B.)     87. 
Lindeman,  Ibid.,  No.  184,  1913.     (Magnetite,  Central  Ont.  Ry.)     88. 
Mackenzie,  Ibid.,  No.  145,  1912.     (Magnetite  sand,  St.  Lawrence  Riv.) 
89.  McConnell,  Can.  Geol.  Surv.,  Mem.  58,  1914.     (Texada,  Id.)     90. 
Miller  and  Knight,  Ont.  Bur.  Mines,  XXII,  Pt.  II,  1914.     (s.  e.  Ont.) 

91.  Moore,  Econ.  Geol.,  V.:  528,  1910.     (Bog  ores  Thunder  Bay,  Ont.) 

92.  Moore,  Ont.  Bur.  Mines,  XVIII:  180,  1909.     (Bog  ore,  English  Riv.) 

93.  Warren,  Amer.  Jour.  Sci.,  XXXIII:  263,  1912.     (Que.)     94.  Wood- 
man, Mines  Branch,  No.  20,   1909.     (N.  S.)     95.  Young,  Can.  Min. 
Jour.,    XXXI:     488.     (N.    B.)     96.  Young,    Internat.    Geol.    Congr., 
Guide  Book  No.   1,   1913.     (N.  B.)     97.  Young,  Ibid.,   No.  7,   1913. 
(Moose  Mtn.,  Ont.) 


CHAPTER  XVI 


COPPER 

Ore  Minerals  of  Copper.  —  Copper-bearing  minerals  are  not  only 
numerous,  but  widely  though  irregularly  distributed.  More  than 
this,  copper  is  found  associated  with  many  different  metals  and 
under  varied  conditions. 

Nevertheless  but  few  copper-bearing  minerals  are  important  in 
the  ores  of  this  metal,  and  the  number  of  important  producing  dis- 
tricts is  comparatively  small. 

The  ore  minerals  of  copper  together  with  their  theoretic  composi- 
tion and  percentage  of  copper  are  as  follows  :  — 


ORE  MINERAL 

COMPOSITION 

PER  CENT  Cu 

Chalcopyrite  .... 
Chalcocite  
Bornite  

CuFeS2 
Cu2S 
Cu5FeS4 

34.5 

79.8 
633 

Enargite  

3  Cu2S,  2  As2S3 

48 

Covellite  
Tetrahedrite  .... 
Tennantite  .... 
Native  copper  .  .  . 
Azurite 

CuS 
Cu8Sb2S7 
Cu8As2S7 
Cu 
2CuCO3  Cu(OH)2 

66.5 
52.06 
57 
100 
55  10 

Malachite 

CuCO3,  Cu(OH)2 

57  27 

Chrysocolla  .... 
Cuprite  

CuSiO3,  2  H2O 
Cu2O 

36.06 

88  8 

Melaconite  
Brochantite  
Atacamite  
Chalcanthite  .... 

CuO 
CuS04,  3Cu(OH2) 
Cu(OH)Cl,  Cu(OH)2 
CuSO4,  5  H2O 

79.84 
62.42 
59.45 
25.4 

Very  few  ores  approach  the  theoretic  percentages  given  above. 
Thus,  in  Michigan,  where  native  copper  is  the  ore  mineral,  this  as 
now  mined  rarely  averages  above  1  per  cent  metallic  copper,  and 
may  fall  as  low  as  .6  per  cent.  At  Butte,  Montana,  the  impor- 
tant copper-bearing  minerals  are  chalcocite,  enargite,  and  bornite, 
but  much  of  the  concentrating  ore  in  1914  averaged  about  2  per 
cent  metallic  copper,  and  smelting  ore  5  per  cent. 

Most  of  the  copper  ores  now  worked  are  of  low  grade,  but  can  be 
profitably  treated  because  of  the  extent  of  the  operations  and  pos- 

568 


COPPER  569 

sibility  of  concentration.  Occasionally  low-grade  ores  are  found 
which  are  self-fluxing,  as  those  of  the  Boundary  District  of  western 
Canada.  The  introduction  of  pyritic  smelting  has  permitted 
the  profitable  treatment  of  low-grade  pyritic-copper  ores,  even  if 
they  carry  no  gold  or  silver.  Complex  ores  of  copper,  lead,  and 
zinc  sulphides  are  more  costly  to  treat,  but  this  expense  may  be 
more  than  made  up  for  by  their  gold  and  silver  contents. 

In  the  unaltered  portion  of  the  ore  body  the  copper  compounds 
are  mainly  sulphides,  but  arsenides  and  antimonides  are  also 
known.  In  the  gossan  the  copper  occurs  as  carbonates,  sulphates, 
silicates,  oxides,  native,  and  more  rarely  as  phosphates,  arsenates, 
antimonates  and  vanadates. 

Gangue  Minerals.  —  Quartz  is  the  commonest  gangue  mineral, 
but  calcite  and  siderite  are  abundant  in  a  few;  barite,  rhodo- 
chrosite,  and  fluorite  are  also  known.  Sericite  is  found  in  some 
veins,  and  so  is  tourmaline  in  certain  tin-copper  and  gold-copper 
ones. 

Metallic  impurities  may  be  present  which  cause  trouble  in  the  reduc- 
tion of  the  ores.  Of  these  zinc  is  the  most  objectionable,  but  bismuth, 
though  rare,  is  also  very  undesirable,  but  can  be  eliminated  by  electrolytic 
refining.  Arsenic,  antimony,  tellurium,  and  selenium  are  partially  elim- 
inated in  smelting,  but  must  be  completely  removed  by  electrolytic- 
methods  to  make  the  copper  pure  enough  for  electrical  work. 

Tellurium  is  not  uncommon  in  some  districts,  and  renders  the  metal 
red-short  even  in  small  amounts.  Silver,  even  if  present  in  as  small 
amounts  as  .5  per  cent,  lowers  the  electric  conductivity,  and  above  3  per 
cent  affects  the  toughness  and  malleability  of  the  copper.  Sulphur  up  to 
.25  per  cent  lowers  the  malleability  and  .5  per  cent  renders  the  metal 
cold-short,  while  .4  or  more  per  cent  phosphorus  makes  it  red-short. 

A  high  percentage  of  silica  is  detrimental,  as  it  requires  too  much  basic 
flux. 

Occurrence  and  Origin.  —  Copper  ores  are  found  in  many 
formations  ranging  from  the  pre-Cambrian  to  the  Tertiary,  and 
the  deposits  have  been  formed  in  many  different  ways.  Indeed 
in  some  cases  more  than  one  mode  of  origin  may  be  represented 
by  the  deposits  of  one  locality  (Clifton,  Ariz^;  Bingham,  Utah), 
which  makes  it  a  little  difficult  to  separate  the  different  occur- 
rences sharply  on  genetic  grounds.  Then  too,  a  difference  of  opin- 
ion sometimes  exists  regarding  the  origin  of  some  one  deposit 
(RioTinto,  Spain). 

A  rough  grouping  might  therefore  be  made  as  follows: 

1.  Magmatic  segregations. 

2.  Contact-metamorphic  deposits,  in  crystalline,  usually  gar- 


570  ECONOMIC   GEOLOGY 

netiferous  limestone,  along  igneous  rock  contacts.  (Clifton- 
Morenci,  Ariz.,  Bingham,  Utah,  etc.) 

3.  Deposits  formed  by  circulating  waters,  and  deposited  in 
fissures,  pores,  or  other  cavities,  or  by  replacement. 

A.  By  ascending  thermal  waters. 

B.  By  waters,  probably  of  meteoric  character,  and  un- 

associated  with  igneous  rocks. 

4.  Lens-shaped  deposits  of  variable    origin  in  crystalline  schists. 
All  cf  these  except  the  first  have  important  representatives  in 

the  United  States,  but  in  many  cases  their  commercial  value 
depends  on  secondary  enrichment  and  not  the  mode  of  primary 
deposition. 

Superficial  Alteration  (2,  4,  11,  12,  14,  17,  18,  19).  —  This  may 
produce  results  of  great  economic  importance,  and  excellent 
examples  of  it  are  seen  in  some  of  the  Arizona  ores,  where  the 
upper  portions  of  the  copper  deposits  are  brown  or  black  ferru- 
ginous porous  masses,  brightly  colored  with  oxidized  copper  min- 
erals such  as  cuprite,  malachite,  azurite,  and  chrysocolla,  while 
below  this  at  a  variable  depth  they  pass  into  sulphides. 

In  weathering,  the  copper  minerals,  such  as  chalcopyrite  or  other 
sulphides,  are  usually  oxidized  first  to  sulphates,  and  subsequently 
changed  to  oxides,  carbonates,  or  silicates,  and  occasionally  even 
to  chlorides.  -A  concentration  of  the  ore  deposit  may  take  place 
partly  by  segregation  and  partly  by  leaching,  and  pockets  of  the 
ore  form,  which  are  surrounded  by  oxidized  iron  minerals  form- 
ing part  of  the  gangue. 

While  the  oxidation  will  not  increase  the  total  copper  content 
of  the  ore  body,  still  it  may  change  it  into  a  more  concentrated 
form,  for  the  carbonates  and  other  oxidized  copper  minerals  con- 
tain more  copper  than  the  original  sulphide.  The  ore  in  the 
gossan  may  therefore  run  from  8  to  30  per  cent  or  more,  while 
below  it  may  show  only  5  per  cent  of  copper  (see  Penrose  under  ore 
deposit  refs.).  These  altered  ores  cannot,  however,  be  more 
cheaply  treated.  If  leaching  follows  oxidation,  the  gossan  may  be 
freed  of  its  ore,  as  at  Butte,  Montana,  where  the  upper  part  of 
the  ore-bearing  fissures  is  poor  siliceous  gangue. 

Below  the  zone  of  oxidation,  there  often  lies  a  zone  of  secondary 
sulphide  enrichment  (p.  481),  of  variable  depth,  followed  still 
lower  down  by  the  primary  ore. 

But  even  with  secondary  enrichment,  the  deposit  may  not 


D, 

5 
•s 

I 


I 
•S 

I 


572  ECONOMIC  GEOLOGY 

carry  more  than  2  to  3  per  cent  of  copper,  and  yet  because  of  its 
concentrating  possibilities  and  size  be  worth  working. 

The  processes  of  secondary  enrichment  have  been  referred  to 
on  p.  481,  and  it  was  shown  there  that  the  work  of  Graton  and 
Murdock  has  demonstrated  that  the  change  is  not  as  simple  or 
direct  as  was  formerly  thought. 

Importance  of  United  States  as  a  Copper  Producer.  —  The 
map,  Plate  L,  sets  forth  clearly  the  distribution  of  copper  ores 
in  the  United  States,  and  statistics  show  the  leading  position  of 
this  country  as  a  world's  producer.  The  following  table  com- 
piled by  Butler  shows  in  an  interesting  way  the  production  of 
copper  according  to  the  geologic  age  of  the  deposits. 

PERCENTAGE 
IN  1913 

Pre-Cambrian.  Michigan;  Jerome,  Ariz.;  Encampment,  Wyo.  15.60 
Paleozoic.  Ducktown,  Tenn.,  and  other  Appalachian  deposits  .  1 . 60 
Mesozoic.  Shasta  County,  Calif.;  Foothills  belt,  Calif.;  Ely, 

Nev.;  Yerington,  Nev.;  Alaska;  Bisbee,  Globe,  and  Ray,  Ariz.; 

Others 36 . 71 

Tertiary.  Butte,  Mont.;  Morenci,  Ariz.;  Santa  Rita,  N.  Mex.; 

Bingham,  Frisco  and  Tintic,  Utah;  Others     . 45.98 

About  82  per  cent  of  the  copper  produced  in  the  United  States  in 
1914  was  obtained  from  four  states,  viz.  Arizona,  Montana,  Utah 
and  Michigan,  named  in  the  order  of  their  output,  nearly  all  of 
the  rest  coming  from  the  Appalachians  and  Cordilleran  region; 
the  ores  of  the  latter  are  often  worked  chiefly  for  their  gold  con- 
tents, with  copper  as  a  secondary  product. 

Magmatic  Segregations 

While  it  is  known  that  copper  sulphides  may  crystallize  from 
a  magma,  chalcopyrite  being  the  best  known  example,  still  few 
cases  of  copper  ores  formed  by  magmatic  segregation  are  known. 
Moreover,  it  is  sometimes  difficult  to  prove  definitely  that  the 
deposit  has  originated  in  this  manner,  in  other  words  whether 
the  copper  sulphide  has  crystallized  from  fusion,  or  has  been 
deposited  from  solution.  The  criteria  that  may  be  used  include: 
(1)  primary  intergrowths  of  sulphides  and  silicates,  (2)  inclusions 
of  sulphides  in  silicates,  (3)  corrosion  of  silicates  by  sulphides,  if 
the  latter  crystallized  later,  and  (4)  absence  of  hydrothermal 
effects.  Metamorphism  may  sometimes  obscure  the  original 
characters  of  the  ore  body. 


COPPER  573 

The  deposits  of  this  class  fall  into  two  groups,  viz.  1,  those 
representing  crystallizations  from  the  magma,  with  the  sulphides 
and  silicates  intergrown,  and  2,  bodies  of  comparatively  pure 
sulphides,  which  are  believed  by  some  to  represent  injections. 

Those  of  the  first  group  usually  show  pyrrhotite  associated  with 
the  chalcopyrite,  the  best  known  example  being  the  Sudbury, 
Ontario,  deposits  (described  under  Nickel) .  In  the  United  States 
a  small  one  has  been  described  from  Elkhorn,  Mont.,  and  another 
from  Knox  County,  Me.1  Of  greater  interest,  however,  is  an 
occurrence  found  in  Plumas  County,  California  (48),  where  a 
norite-diorite  carries  bornite,  chalcopyrite  and  magnetite  associ- 
ated with  the  silicates  in  such  a  way  as  to  leave  little  doubt  of 
their  magmatic  origin. 

Another  interesting  deposit  is  found  near  Apex,  Colo.  (50),  and 
consists  of  primary  bornite  and  chalcopyrite,  intergrown  with 
silicates  in  monzonitic  dikes. 

Of  the  injected  pyritic  deposits,  the  best  known  cases  perhaps 
are  those  of  Roros  and  Sulitjelma,  Norway,  where  great  flat 
lenses,  carrying  pyrite,  chalcopyrite  and  pyrrhotite  are  found 
in  metamorphic  schists,  closely  associated  with  metamorphosed 
gabbro,  and  sometimes  in  it.  Their  intrusive  nature  may  be 
doubted  by  some. 

Others  are  known  at  Bodenmais,  Bavaria  2  and  Falun,  Sweden.3 

Contact — Metamorphic  Deposits 

Some  of  the  most  important  copper  deposits  of  the  world 
belong  not  only  to  this  type,  but  are  located  in  the  United  States. 
It  should  be  pointed  out,  however,  that  the  ores  of  some  of  these 
districts  are  not  exclusively  of  this  type,  but  include  several 
others  which  are  closely  associated  genetically.  Moreover,  while 
in  some  cases  it  was  the  true  contact-metamorphic  ores  that  were 
first  worked  at  some  of  these  localities,  the  other  types  are  now 
the  important  sources  of  production.  There  are  included  under 
this  heading  also  certain  deposits,  which  have  the  proper  min- 
eralogic  characters,  but  show  no  closely  associated  intrusive. 

United    States.     Bisbee    or    Warren    District    (32,    34,  37).- 
This  district,  which  contains  the  famous  Copper  Queen  Mine, 
lies  on  the  eastern  slope  of  the  Mule  Pass  Mountains  (Fig.  183), 

1  Journ.  Geol.,  XVI:  124,  1908. 

2  Weinschenk,  Zeitschr.  prak.  Geol.,  1900:   65. 

3  Sjogren,  Internal.  Geol.  Cong.,  Stockholm,  1910,  Guidebook. 


574 


ECONOMIC   GEOLOGY 


but  a  short  distance  from  the  Mexican  boundary.  The  section 
at  that  locality  involves  strata  from  pre-Cambrian  to  Creta- 
ceous age,  with  an  important  unconformity  between  the  Carbon- 
iferous and  Cretaceous  (Fig.  185).  Prior  to  the  deposition  of 


WiUiama  Engraving  C«.,  N.Y 


FIG.  183.  —  Map  of  Arizona,  showing  location  of  more  important  mining  districts. 

(After  Lindgren.) 

the  latter  the  rocks  had  been  broken  by  numerous  faults  (Fig.  184), 
one  of  these,  the  Dividend  fault,  being  specially  prominent  in 
forming  one  boundary  of  the  ore-bearing  area.  This  was  followed 
by  intrusions  of  a  granite  magma  forming  dikes,  sills,  or  irregular 
stocks,  which  have  metamorphosed  the  Carboniferous  limestones, 
with  the  production  of  characteristic  contact  minerals. 


COPPER 


575 


The  Carboniferous  limestone  forms  a  shallow  basin,  which  is 
cut  through  by  the  Dividend  fault.  The  principal  ore  bodies 
lie  around  the  porphyry  stock,  and  along  faults  and  fissures 
where  .replacement  of  the  limestone  has  occurred.  Most  of  the 


576 


ECONOMIC   GEOLOGY 


ore  has  been  developed  in  the  Carboniferous  and  Devonian  lime- 
stones, though  in  recent  years  important  bodies  have  been  dis- 
covered in  the  Cambrian,  and  some  even  in  the  granite  porphyry. 
The  ore  bodies  form  large,  irregularly  distributed,  but  rudely 
tabular  masses.  The  ore  consists  of  malachite,  azurite,  cuprite, 
and  other  oxidized  copper  minerals  above,  which  pass  at  variable 
depths  into  unaltered  sulphides;  but  between  the  two,  or  at  least 


Red  nodular  shales  with  cross-bedded,  buff, 
tawny,  and  red  sandstones.    A  few  beds  of 
impure  limestone  near  base.  Uncomformably 
overlain  by  fluviatile  Quaternary  deposits. 


fhiuk-bedded.  hard,  gray,  fossiliferous 


Buff,  tawny  and  red  sandstones  and  dark- 
red  shales,  with  an  occasional  thin  bed  of 
impure  limestone  near  top. 


lieu'..'!  cjoslomerate  with  rather  angular 
pebbles  chief) v  schist  andJimestont. .Rests 
on  irregular  surface  produced  by  erosion. 


Chiefly  light-gray,  compact  limestone  in 
beds  of  moderate  thickness.  Contains 
abundant  fossils.  Cut  by  granite-porphyry 


Thick-bedded,  white  &  light-gray , 'limestone 
Contains  abundant  crinoid  stems.    Cut  by 


granite-porphyry. 

Dark-gray  fossiliferous  limestone  in  beds  of 
moderate  thickness,  Cut  by  granite-porphyry. 


Thin-bedded,  impure  oherty  limestones 
Cut  "by  granite-porphyry. 


Moderately  thick,  cross-bedded  quarts,  with 
basal  conglomerate.  Cufby  granite-porphyry; 


Sericite-schists.  Cut  by  granite  arid  granite . 
porphyry. 


Cinlura  formation,  1,800  feet 
plus  unknown-thickness, 
removed  by  erosion* 


Mural  limestone,  650  feet. 


Morita  formation  1,800  feet. 


Glance  conglomerate, 

25to500.f 

Great! 


•  conglomerate, 

iOO.feet. 

unconformity, 


Naco  limestone,  3,000  feet 
plus  unknown  thickness, 
removed  by  pre-Cretaceous 


Escabrosa  limestone. 
700  feet. 


Abrigo  limestone.  770  .feet. 


Great-unconformity. 


FIG.  185.  —  Geological  section  at  Bisbee,  Ariz.     (After  Ransome,  U.  S.  Geol.  Sun. 

Prof.  Pap.  21.) 


never  far  from  the  effects  of  oxidation,  masses  of  massive  or  sooty 
chalcocite  are  frequently  found. 

The  primary  ore  consists  of  pyrite,  chalcopyrite,  with  smaller 
bodies  of  galena  and  some  sphalerite,  and  was  deposited  by 
metasomatic  replacement  of  the  limestone.  As  originally  formed, 
the  deposits  usually  contained  too  little  copper  to  make  them 
commercially  valuable,  but  they  have  been  subsequently  enriched 
by  secondary  enrichment.  Large  bodies  of  primary  sulphides 
of  commercial  grade  have  been  recently  developed. 


COPPER 


577 


The  general  relations  of  these  ores  to  the  intrusive  porphyry  and 
the  contact  silicates  indicate  that  they  are  of  contact-metamorphic 
origin. 

In  some  cases  an  iron  gossan  has  indicated  an  underlying  ore 
body,  but  many  others  do  not  outcrop. 


LEGEND 

SEDIMENTARY  ROCKS 


<^  Pinkard  formation 

( Shales  and  sandstones, 
partly  metamorphosed) 


How  formation 

(cherty  limestones 

and  lime  shales) 

METAMORPHIC  ROCKS 


stone  now  garnet,  epidote 


GEOLOGIC  MAP  OF  THE  VICINITY  OF  MORENCI 
ARIZONA 


Contact  inetamorphic  limestone 
and  shale  of  Paleozoic  age 


phic  lime- 


K      uartz-inonzonite-porpbyry 

S2// 

^  Faults        H  Shafts 
\  /  Drainage 

FIG.  186.  —  Geologic  map  of  vicinity  of  Morenci,  Ariz.     (From  Weed.) 


In  1914  the  average  copper  recovery  of  the  Bisbee  ores  was 
about  5.4  per  cent  and  the  average  precious  metals  value  about 
$1.35  per  ton  of  ore. 

Clifton-Morenci  District  (33) .  —  The  copper  deposits  of  this  dis- 
trict are  located  at  Morenci  (Fig.  183)  and  Metcalf  in  eastern 
Graham  County.  The  ores  were  discovered  in  1872,  but  remained 
undeveloped  for  a  long  time  because  of  the  fact  that  they  were  of 
too  low  grade,  and  too  far  from  the  railroads. 


578 


ECONOMIC   GEOLOGY 


At  the  present  time,  however,  these  large  bodies  of  low-grade  ore 
are  utilized,  most  of  the  work  being  done  by  three  large  companies. 

The  geologic  section  involves  the  following : 
Quaternary  (Gila)  conglomerate. 

Tertiary  flows  of  basalt,  rhyolites,  and  some  andesites. 
Cretaceous  shales  and  sandstones.     Several  hundred  feet  thick. 
Lower  Carboniferous  heavy-bedded  pure  limestones,  180  feet. 
Devonian  (?)  shale  and  argillaceous  limestone,  100  feet. 
Ordovician  limestone,  200  to  400  feet. 
Cambrian  (?)  quartzitic  sandstone,  200  feet. 
Pre-Cambrian  granite  and  quartzitic  schists. 

Intrusions  of  granitic    and   dioritic   porphyries  of  post-Cretaceous   age 
pierce  all  the  older  rocks,  forming  stocks,  dikes,  laccoliths,  and  sheets. 

All   of  these   rocks  have  been  bowed   up  and   subsequently 
faulted  by  late  Cretaceous  or  early  Tertiary  movements. 


Copper  Mt. 


Dike 


Fault 


Fault 


FIG.  187.  —  Section  in  Morenci,  Ariz.,  district.  P,  porphyry;  S,  unaltered  sedi- 
ments; F,  fissure  veins;  M,  metamorphosed  limestone  and  shale;  O,  contact- 
metamorphic  ores;  R,  disseminated  chalcocite.  (After  Lindgren,  Eng.  and  Min. 
Jour.,  LXXVIII.) 


FIG.  188.  —  Photo-micrograph  showing  replacement  in  Clifton-Morenci  ores.  Dark 
gray  chalcocite,  developing  by  replacement  of  pyrite  (light  gray).  The  chalco- 
cite is  accompanied  by  small  amounts  of  microcrystalline  quartz,  sericite  shreds, 
and  kaolin.  Black  areas  represent  open  field.  (After  Lindgren,  U.  S.  Geol.  Surv., 
Prof.  Pap.  43.) 


COPPER 


579 


Briefly  stated,  the  distribution  of  the  deposits  of  copper  (Fig. 
187)  ore  is  practically  coextensive  with  a  great  porphyry  stock 
and  its  dike  systems,  the  deposits  occurring  either  in  the  por- 
phyry or  close  to  its  contact,  as  well  as  along  dikes  of  por- 
phyry in  gome  other  rock. 

The  original  ores  were  pyrite  and  chalcopyrite,  of  too  low  grade 
to  be  workable,  but  they  have  since  become  so  by  a  process  of 
secondary  enrichment.  No  ores  were  formed  before  the  porphyry 
intrusion. 

Where  the  latter  is  in  contact  with  the  granite  and  quartzite, 


4500 


Scale 


15o~ 


'500  feet 


FIG.  189.  —  Vertical  section  of  ore  body  in  Clifton-Morenci  district,  showing  con- 
tact metamorphosed  limestone.  (After  Lindgren,  U.  S.  Geol.  Surv.,  Prof.  Pap. 
43.) 

but  little  change  is  produced,  but  where  the  porphyry  is  found 
adjoining  the  limestones  or  shales,  extensive  contact  metamorphism 
developed,  resulting  in  the  formation  of  large  masses  of  garnet  and 
epidote,  especially  in  the  Lower  Carboniferous  limestones. 

Where  alteration  has  not  masked  the  phenomena,  magnetite, 
pyrite,  chalcopyrite,  and  zinc  blende  accompany  the  contact 
minerals. 

The  ore  bodies  in  the  limestone  are  often  irregular,  but  more 
frequently  roughly  tabular,  because  of  the  accumulation  of  the 
minerals  along  the  stratification  planes,  or  walls  of  dikes. 

In  many  parts  of  the  district  the  copper  occurs  in  fissure  veins 
which  cut  porphyry,  granite,  and  sedimentary  rocks,  and  were 


580  ECONOMIC   GEOLOGY 

probably  formed  shortly  after  the  consolidation  of  the  porphyry. 
These  in  the  lower  levels  carry  pyrite,  chalcopyrite,  and  sphalerite, 
but  no  magnetite.  Surface  leaching  of  these  veins  has  often  left 
limonite-stained,  silicified  porphyry  outcrops. 

Accompanying  these  veins,  and  of  more  importance  commercially, 
are  often  extensive  impregnations  of  the  country  rock.  These 
disseminated  deposits  in  the  highly  altered  porphyry  are  leached 
out  above,  but  lower  down  show  a  zone  of  pyrite  and  chalcocite, 
which  does  not  usually  extend  below  400  feet. 

Most  of  the  copper  in  the  district  is  obtained  from  concentrating 
ores  containing  chalcocite  in  altered  porphyry.  In  1914  the  yield 
of  copper  from  the  concentrating  ores  was  1.65  per  cent,  while 
the  smelting  ores  gave  an  average  yield  of  4.7  per  cent. 

The  precious  metal  content  is  so  low  that  much  of  the  output 
of  this  district  is  not  refined  electrolytically  unless  the  copper  is 
not  pure  enough  to  put  on  the  market. 

The  intrusions  of  porphyry  produced  strong  contact  metamor- 
phism  in  the  shales  and  limestones  of  Paleozoic  age,  resulting  in  the 
contemporaneous  and  metasomatic  development  of  various  con- 
tact silicates  and  sulphides,1  the  contact  zone  thus  receiving 
large  additions  of  iron,  silica,  sulphur,  copper,  and  zinc,  sub- 
stances unknown  in  the  sedimentary  series  away  from  the  por- 
phyry. 

Subsequent  to  the  solidification  of  the  porphyry,  extensive 
fissuring  occurred  in  both  it  and  the  sediments,  resulting  in  the 
deposition  of  quartz,  pyrite,  chalcopyrite,  and  zinc  blende  in  the 
fissures  and  by  replacement  of  the  wall  rock.  These  are  low  in 
copper,  but  there  is  a  close  relation  between  the  veins  and  contact 
deposits  because  of  the  similarity  of  their  metallic  contents,  and 
of  the  similar  development  of  tremolite  and  diopside  where 
limestone  forms  the  wall.  The  extensive  impregnation  of  the 
porphyry  also  occurred  at  this  time.  Subsequent  exposure  of 
the  deposits  by  erosion  permitted  the  entrance  of  surface  waters 
which  was  followed  by  weathering  and  secondary. enrichment. 

Bingham  Canon,  Utah  (101,  102). — This  camp,  which  is  the 
leading  copper-producing  locality  of  Utah,  is  situated  in  the  north- 
central  part  of  the  state,  on  the  eastern  slope  of  the  Oquirrh 
Mountains,  20  miles  southwest  of  Salt  Lake  City. 

The  rocks  of  this  area  include  a  great  thickness  of  Carbonif- 

1  Garnet,  epidote,  diopside,  etc.,  pyrite,  magnetite,  chalcopyrite  and  sphalerite. 


582  ECONOMIC   GEOLOGY 

erous  sedimentary  formations,  which  are  divisible  into  a  lower 
member  of  massive  quartzite  with  several  interbedded  limestones, 
and  an  upper  member  of  quartzite  with  black  calcareous  shales, 
sandstones,  and  limestones. 


FIG.  190. — Thin  section  of  altered  porphyry,  from  Clifton-Morenci  district,  con- 
taining grains  of  pyrite  surrounded  by  chalcocite  (both  black).      X18. 

The  sediments,  though  showing  in  general  a  northerly  dip,  and 
northeast-southwest  strike  throughout  the  region,  vary  in  their 
strike  from  east-west  on  the  western  slope  to  north-south  on  the 
eastern,  so  that  they  form  a  synclinal  basin,  with  northward 
pitch. 

The  whole  series  of  sediments,  but  especially  the  lower  member,  is 
pierced  by  an  igneous  intrusion,  forming  dikes,  sills,  and  laccoliths. 
Prominent  among  these  are  two  large  areas  of  monzonite,  one  form- 
ing an  irregular  laccolith,  the  other  a  broad  irregular  stock.  An 
extensive  latite  flow,  outcropping  on  the  eastern  slope  of  the  ranges, 
covered  some  of  the  sediments  and  older  intrusives. 

There  has  been  fissuring  at  several  different  periods  following  the 
igneous  intrusion,  but  in  most  cases  displacement  along  these  frac- 
tures does  not  exceed  150  feet.  The  northwest-southeast  fissures 
carry  the  most  important  lead-silver  ores. 

The  limestones  of  the  lower  member,  averaging  200  feet  in  thick- 
ness, have  been  highly  marbleized,  and  carry  large  bodies  of  copper 


PLATE  LIT 


FIG.  1.  —  Smelter  of  Arizona  Copper  Company,  Clifton,  Ariz.     (After  Church,  Min. 

Mag.,  X.) 


FIG,  2.  —  View  of  Bingham  Canon,   Utah.     (After  Keith,   U,  S.  Geol.  Surv.,  Prof. 

Pap.  38.) 

(583) 


584 


ECONOMIC   GEOLOGY; 


ore,  and  the  calcareous  carbonaceous  shales  of  the  upper  member 
sometimes  carry  it  as  well. 

In  many  cases  the  ore  is  closely  associated  with  the  intrusives. 

Two  types  of  copper  deposits  are  recognized,  viz. :  (1)  great 
tabular  replacement  masses  in  limestone,  lying  roughly  parallel  with 
the  bedding,  and  showing  sometimes  an  extent  of  several  hundred 
feet  along  the  strike,  as  well  as  a  thickness  of  even  200  feet;  (2)  dis- 
seminations in  a  large  monzonite  laccolith,  especially  in  the  fractured, 
fissured,  and  altered  portions  of  the  same. 

The  contact  replacement  deposits  have  been  important  ones  in 
the  past,  but  the  enormous  bodies  of  low-grade  disseminated  ore  in 
the  monzonite  are  now  the  most  important  (PL  LI) . 

The  limestone  ores  consist  of  primary  pyrite  and  chalcopyrite, 
enriched  in  some  cases  by  chalcocite  and  tetrahedrite.  Quartz  is 
the  chief  gangue  mineral,  but  as  might  be  expected  in  a  contact 
deposit,  garnet,  epidote,  tremolite,  specularite,  pyrrhotite,  sphalerite, 
galena,  etc.,  are  also  present. 

The  primary  ore  of  the  disseminated  type  consists  of  grains 
and  veinlets  of  pyrite  and  chalcopyrite,  distributed  through  both 


FIG.  191.     Section  showing  replacement  of  limestone  by  pyrite  (P)   and  chalcocite 
(Ch).     Quartz  (Q).     (After  Boutwell,  U.  S.  Geol.  Surv.,  Prof.  Pap.  38.) 


COPPER  585 

shattered  and  altered  monzonite  porphyry  and  quartzite.  The 
commercial  ore  is  due  to  secondary  enrichment,  and  the  zone 
containing  it  underlies  the  leached  or  partly  leached  capping, 
and  overlies  the  primary  ore.  In  this  ore  zone,  whose  average 
thickness  is  about  165  feet,1  the  secondary  sulphides  are  covellite 
and  chalcocite.  The  average  thickness  of  the  capping  was  115 
feet. 

The  theory  of  origin  advanced  by  Boutwell  is  that  the 
quartzites  and  limestones  were  intruded  by  the  monzonite  in 
Mesozoic  or  early  Tertiary  times,  producing  contact  metamorph- 
ism  of  the  limestone  and  replacing  it  with  sulphides. 

After  the  upper  portion  of  the  monzonite  intrusion  was  partly 
cooled,  the  inclosing  rocks  were  fractured  by  northwest -southeast 
fissures,  along  which  there  ascended  heated  aqueous  solutions  from 
the  deeper,  un cooled  portions  of  the  magma.  These  solutions  not 
only  altered  the  fissure  walls,  but  deposited  additional  metallic 
sulphides,  thus  enriching  the  limestones  as  well  as  altering  the 
monzonite  by  the  addition  of  copper,  gold,  silver,  pyrite,  and 
molybdenite. 

In  1914  the  ore  treated  at  the  mills  of  the  Utah  Copper  Company 
had  an  average  copper  content  of  1.425  per  cent,  with  an  average 
recovery  of  66.04  per  cent. 

Ely,  Nevada  (79,  81).  —  This  district,  although  of  recent  develop- 
ment, promises  to  become  of  great  importance.  The  copper  belt, 
which  lies  6  miles  west  of  Ely,  in  White  Pine  County  (Fig.  232) ,  is 
about  one  mile  wide  and  six  miles  long  extending  in  an  east-west 
direction. 

It  lies  in  a  pass  through  the  Egan  Range,  along  what  used  to  be  a 
route  to  Eureka,  Nevada. 

The  section  there  involves  the  following  formations:  — 
Ruth  limestone 

Arcturus  limestone  1000  feet 

Ely  limestone,  Carboniferous  1500  feet 

White  Pine  shale  \  ^  1000  feet 

XT       i    T  ( Devonian  .,  »„„  .    . 

Nevada  limestone  J  1000  feet 

The  sediments  which  have  a  gentle  dip  are  cut  by  a  coarse-grained 
quartz  monzonite,  which  has  effected  only  a  limited  amount  of 
alteration  in  the  adjacent  limestone,  producing  some  garnet  rock 
and  chalcopyrite.  ,-  : 

There  are  present  also  dikes  of  porphyry  and  rhyolite  lavas,  the 

i  On  property  of  Utah  Copper  Company. 


586 


ECONOMIC   GEOLOGY 


latter  resting  on  the  uneven  limestone  surface  (Fig.  192),  but  these 
eruptives  bear  no  genetic  relation  to  the  ore. 

Of  importance  in  this  connection  are  the  monzonite  intrusions, 
which  carry  ore.  The  ore,  consisting  of  pyrite  and  chalcocite,  is 
disseminated  through  the  much  altered  and  shattered  monzonite 
porphyry  and  there  is  a  sharp  line  of  separation  between  the  gossan 
and  unoxidized  bluish  white  rock  containing  the  grains  of  pyrite 
and  chalcocite.  The  oxidized  zone  on  the  average  extends  to  a 


FIG.  192.  —  Section  of  Ely,  Nev.,  district.     (From  Weed.) 

depth  of  100  to  150  feet,  while  a  thickness  of  ore  ranging  from 
190  to  280  feet  has  been  determined. 

Some  of  the  ore  bodies  are  of  great  size,  that  at  the  Ruth  mine 
having  a  width  of  50  to  not  less  than  250  feet,  and  being  developed 
for  a  length  of  not  less  than  900  feet. 

Lawson  believes  that  the  ore  bodies  have  resulted  from  a  leach- 
ing of  secondary  ores  in  the  oxidized  zones  and  that  the  only 
primary  ore  now  known  is  the  chalcopyrite  in  the  garnet  rock 
occurring  beneath  the  quartz  "  blouts."  These  latter  are  masses 
of  quartz  occurring  mainly  along  the  contact,  and  formed  by  the 
replacement  of  both  limestone  and  porphyry  with  silica  which 
was  leached  out  of  the  porphyry  by  carbonated  waters. 

The  ores  are  worked  in  part  as  open  cuts  (PL  LIII,  Fig.  2), 
and  the  average  copper  content  of  those  mined  in  1914  was 
1.483  per  cent. 

Other  Deposits.  —  Among  the  other  deposits,  yielding  copper  ores  in  part 
or  wholly  of  the  contact  metamorphic  type  may  be  mentioned  those  of  the 
following  districts;  Santa  Rita,  N.  M.  (85);  Yerington,  Nev.  (78,  80);  Silver 
Bell,  Ariz.  (40).  The  first  named  of  these  is  becoming  important  chiefly 
on  account  of  its  great  disseminated  deposits  in  highly  altered  and  shattered 
sedimentary  and  intrusive  rocks,  in  which  the  copper  occurs  largely  native 
or  as  the  oxide,  although  chalcocite  is  by  no  means  uncommon. 


PLATE  LIII 


FIG.  1.  —  View  looking  northeast  from  the  Eureka  ore  pit  of  the  Nevada  Consoli- 
dated Copper  Company,  Ruth,  Ely  district,  Nev.     (D.  Steel,  photo.) 


FIG.  2.  —  South  end  of  the  Eureka  ore  pit,  Ruth,  Nev.     The  hills  in  the  back- 
ground are  limestone  at  the  top  and  porphyry  at  the  base.     (Z>.  Steel,  photo.) 

(587) 


588 


ECONOMIC   GEOLOGY 


Alaska.  Ketchikan  District  (26,  28).  —  The  most  important 
ore  bodies  are  contact-metamorphic  ones  occurring  in  irregular 
masses  from  10  to  250  feet  in  dimensions,  along  the  contacts  of 
the  intrusive  rocks,  usually  with  limestones,  the  ore  composed 
mainly  of  chalcopyrite,  magnetite,  pyrrhotite,  and  pyrite  in  a 
gangue  of  amphibole,  orthoclase,  epidote,  garnet,  and  calcite. 


.6  mile. 


FIG.  193.  —  Geologic  map  of  Copper  Mountain  Region,  Prince  of  Wales  Island, 
Alas.     (After  Wright,  U.  S.  Geol.  Surv.,  Bull  379.) 

In  addition  to  these  there  are  lode  deposits  in  shear  zones,  vein 
deposits  in  fissures,  and  disseminated  ores. 

The  ores  mined  are  somewhat  low  in  grade,  with  a  little  gold  and 
silver,  but  high  in  iron  and  lime,  and  form  a  desirable  flux  for 
smelters  of  Tacoma  and  British  Columbia. 

At  Copper  Mountain  in  the  Hetta  Inlet  district  (Fig.  193)  the 
ores  are  (1)  contact  deposits  occurring  between  granite  and  lime- 


PLATE  LIV 


FIG.  1.  —  View  from  open  cut  of  Old  Dominion  mine,  Globe,  Ariz.,  looking  towards 
Miami.  Rocky  surface  beyond  tank,  weathered  dacite;  low  ridges  beyond 
creek,  Gila  conglomerate.  (H.  Ries,  photo.) 


.  2.==  Open  cut,  Mother  Lode  mine,  near  Greenwood,  Brit.  Col.     Right  wall, 
limestone;  left  wall,  contact  metamorphosed  rock.     (H.  Ries,  photo.) 

(589) 


590 


ECONOMIC  GEOLOGY 


stone  or  schist,  and  (2)  vein  or  shear  zone  deposits,  occurring 

along  the  bedding  planes  of  the  greenstone  schist  and  quartzites. 

The  contact  zone  is  of  variable  width  and  is  broadest  in  the 

limestone. 

Canada    (117,   118).     Boundary    District,  British    Columbia.— 

Copper  ores,  which  in  many  respects  possess  the  characteristics  of 

contact-metamorphic  deposits,  are 
found  in  the  Boundary  District  of 
southern  British  Columbia.  In  the 
Phoenix  area  the  geologic  section 
involves  the  following  formations : 

Tertiary.  Pulaskite  porphyry, 
augite  porphyrite  and  trachyte 
flows;  conglomerate,  sandstone  and 
shale. 

Jurassic.     Granodiorite;    a  bath- 
olith,  probably  underlying  Phoenix. 
Carboniferous.     Rawhide  forma- 
tion.    Argillites. 

Brooklyn  formation,  with:  (1) 
Mineralized  zone  of  garnet, 
epidote  and  ore;  (2)  zone  of 
j  asperoids,  tuffs,  argillites  and 
altered  basic  intrusives;  and 
(3)  crystalline  limestone. 
Knob  Hill  group.  Massive 
breccias,  tuffs,  and  cherts, 
with  argillites  and  limestone. 
Crustal  disturbances  have 
obscured  the  relationships  of 
the  different  formations. 

The  lenticular  ore  bodies  lie  in 
basin-shaped  troughs  in  the  jasper- 
oid  zone  and  crystalline  limestone 
(Fig.  194).  The  average  ore,  which 
is  self-fluxing,  ranges  from  1.2  to  1.6  per  cent  copper,  and  the 
metallic  minerals,  which  are  disseminated  through  the  gangue, 
along  fracture  and  cleavage  planes  (Fig.  195),  consist  of  chalco- 
pyrite,  pyrite,  specular  hematite  and  magnetite.  The  gangue 
minerals  are  epidote,  garnet,  actinolite,  quartz,  calcite  and  chlorite. 


COPPER 


591 


At  Deadwood   (117)    the  geological  formations  and  ores  are 
similar  to  those  occurring  at  Phoenix.     Fig.  196  shows  a  section 


FIG.  195.  —  Thin  section  of  crystalline  limestone  containing  branched  veinlet  of 
sulphides,  from  Phoenix,  B.  C.      X33. 

across  the  Mother  Lode  ore  body  at  Deadwood.     The  ore  here 
consists  of  a  massive  mixture  of  chalcopyrite,  pyrite  and  mag- 


FIG.  196.  —  Section  through  Mother  Lode  ore  body  at  Deadwood,  B.  C.  O,  ore; 
C,  crystalline  limestone,  Brooklyn  formation;  Cl,  mineralized  contact  meta- 
morphic  zone  of  C;  Gd,  granodiorite;  Khl,  Knob  Hill  group,  chert  tuff  zone; 
Kh2,  Knob  Hill  group,  jasperoid  tuff  zone;  G,  clay,  sand,  gravel.  (After 
Le  Roy,  Can.  Geol.  Surv.,  Mem.  19.) 

netite,  finely  and  uniformly  distributed  along  fracture  and  cleav- 
age planes  in  the  gangue  minerals,  which  consist  chiefly  of  contact 
silicates.  The  ore  carries  1.1-1.3  per  cent  copper,  and  $1.00  gold 
and  silver  per  ton. 


592  ECONOMIC   GEOLOGY 

Whitehorse,  Yukon  Territory.  —  These  deposits  are  located 
in  southern  Yukon  Territory.  They  consist  of  contact  metamor- 
phic  deposits  in  Carboniferous  limestone  near  its  contact  with  a 
Mesozoic  granite.  The  chief  ore  minerals  are  bornite  and  chal- 
copyrite,  with  occasional  tetrahedrite  and  chalcocite.  Iron 
sulphides  are  not  abundant,  but  iron  oxides  are  common  and  may 
form  separate  masses.  The  non-metallic  gangue  is  chiefly  andra- 
dite,  augite,  tremolite  and  calcite.  The  general  average  of 
copper  contents  is  4  per  cent,  and  gold  and  silver  are  present,  but 
not  in  large  amounts  (119). 

Mexico.  —  The  copper  deposits  of  Cananea,1  which  are  in  part  of  the  con- 
tact metamorphic  type,  are  well  known.  They  have  been  developed  in  Pale- 
ozoic limestones,  by  the  intrusion  of  diorite  porphyry  and  granodiorite,  and 
carry  chalcopyrite,  sphalerite,  bornite,  magnetite,  hematite  and  galena,  in  a 
gangue  of  contact  silicates.  Of  greater  importance,  however,  are  the  lodes 
and  disseminations  in  sericitized  and  silicified  diorite  porphyry.  Other 
interesting  deposits  occur  at  San  Jose,2  Matehuala  3  and  Velardena.4 


Deposits  Formed  by  Circulating  Waters 

This  grouping  includes  deposits  of  the  fissure  vein  or  related 
types  which  have  been  formed  by  cavity  filling  or  replacement, 
and  is  further  subdivided  into :  (A)  those  deposited  by  ascending 
thermal  solutions,  evidently  of  magmatic  origin,  and  (B)  those 
deposited  by  waters,  probably  of  meteoric  character,  and  unassoci- 
ated  with  igneous  rocks. 


A.  Deposits  Formed  by  Ascending  Thermal  Waters 

This  group  includes  copper  ore  bodies  formed  in  the  lower 
vein  zone,  and  those  deposited  at  intermediate  depths. 

Lower  Vein  Zone. — Copper  veins  or  lodes  carrying  tourmaline 
as  a  high  temperature  index  mineral  have  been  described  from  a 
number  of  localities.  In  the  United  States  the  most  important 
deposit  is  that  found  in  the  Cactus  mine  of  southern  Utah.  This 
is  a  low-grade  chal copy rite-py rite  ore  containing  tourmaline  and 
occurring  in  a  brecciated  area  of  sericitized  and  tourmalinized 

lEmmons,  S.  F.,  Econ.  Geol.,  V:   312,  1910. 
2  Kemp,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXVI:    178,  1905. 
8  Spurr,  Carrey  and  Fenner,  Econ/  Geol.,  VII:   444,  1912. 
4  Spurr  and  Garrey,  Ibid.,  Ill:   688,  1908. 


COPPER  593 

post-Paleozoic  monzonite.     Other  deposits  are  known  at  Copper- 
opolis,  Ore.,1  and  Meadow  Lake,2  Calif. 

In  Canada,  a  somewhat  important  example  of  this  type  occurs 
at  Rossland,  Brit.  Col.  (115).  Here  the  Carboniferous  sediments 
have  been  cut  by  a  series  of  extrusives  and  intrusives  ranging 
from  Triassic  to  Tertiary  in  age,  with  several  periods  of  deforma- 
tion and  two  of  mineralization.  The  ores  occur  as  replacements 
along  fissures  and  sheeted  zones,  chiefly  in  the  augite-porphyrite 
and  monzonite,  with  pyrrhotite  and  chalcopyrite  as  the  ore  min- 
erals in  a  gangue  of  altered  country  rock.  Hydrothermal  alter- 
ation of  the  wall  rock  is  marked,  the  high  temperature  conditions 
being  indicated  by  the  development  of  biotite,  and  also  some 
tourmaline,  garnet,  wollastonite  and  epidote. 

The  values  run  about  .7-3.6%  Cu;  .4-1.2  oz.  Au;  and  .3-2.3 
oz.  Ag. 

Deposits  of  the  Intermediate  Vein  Zone.  —  These  consist 
usually  of  deposits  of  the  fissure  vein  type,  but  sometimes  form 
disseminations,  etc.  They  include  a  large  number  of  very 
important  deposits. 

United  States.  Montana  (70-77).  —  The  mining  camp  of 
Butte  is  of  importance  and  interest  both  on  account  of  the  size 
and  extraordinary  richness  of  its  deposits,  all  of  which  have 
combined  to  make  it  the  greatest  copper-producing  camp  of  the 
world. 

Up  to  August,  1913,  it  had  yielded  in  round  numbers, 
6,000,000,000  pounds  copper;  260,000,000  ounces  gold;  1,250,000 
ounces  silver;  and  a  large  but  not  definitely  known  tonnage  of 
zinc  (74). 

Butte  lies  on  the  western  border  of  the  Boulder  batholith,  the 
latter  having  a  width  of  75  miles  and  a  length  of  over  100  miles. 

Lying  between  the  main  range  of  the  Rocky  Mountains  on  the 
east,  and  the  Bitterroot  Mountains  on  the  west,  the  batholith 
seems  to  have  been  intruded  in  the  Eocene  (?)  after  a  period 
of  folding  and  thrust  faulting,  and  without  causing  any  doming. 

Associated  with  the  batholith  are  a  number  of  fissure  veins, 
one  type  of  which  is  found  only  in  the  Butte  district,  and  there- 
fore concerns  us  here.  The  rocks  of  the  Butte  district  include: 
(1)  Granite  or  quartz  monzonite,  the  Butte  granite,  much  jointed, 
and  hence  permeable  to  solutions;  (2)  Aplite,  in  irregular  bodies 

1  Lindgren,  U.  S.  G.  S.t  22d  Ann.  Kept.,  Pt.  2,  p.  551. 

2  Lindgren,  A.  J.  S.,  XLVI:   201,  1893. 


594 


ECONOMIC   GEOLOGY 


•  SILVER  VEINS 
COPPER  VEINS 


|  J    Pal  -  ALLUVIUM  AND  WASH  PLEISTOCENE  

|ffij*j    Nr!  -  INTRUSIVE  RHYOLITE  NEOCENE 

fiiil    ap-    APLITE      ) 

~~~  >•  POST  CARBONIFEROUS 

K^''?Al    V-    GRANITE   ) 

FIG.  197.  —  Map  of  eastern  part  of  Butte,  Mont.,  district,  showing  distribution  of 
veins,  and  geology.      ( U.  S.  Geol.  Sure.) 

and  dikes,  especially  in  the  northwestern  portion  of  the  district; 
(3)  Quartz  porphyry  dikes,  roughly  parallel  in  an  east-west 
direction,  and  following  the  earliest  vein  system;  (4)  Rhyolite, 
of  intrusive  and  extrusive  character,  especially  in  west  and  north- 
west part  of  district,  its  offshoots  cutting  both  the  copper  and  silver 
veins;  (5)  Andesite,  of  pre-Tertiary  age  and  bearing  no  relation 
to  the  ores. 


COPPER 


595 


The  granite  is  cut  by  many  faults,  which  are  hard  to  detect, 
and  which  are  often  mineralized.  Fissures  are  common  in  the 
batholith,  and  there  are  two  main  series,  striking  east-west,  and 
northwest-southeast,  correspond- 
ing broadly  to  the  two  most 
important  fracture  zones  of  the 
district. 

There  have  been  identified  six 
distinct  fissure  systems,  which  cut 
the  granite,  aplite  and  quartz- 
porphyry,  but  not  always  the 
rhyolite,  and  displacement  is 
found  along  some.  These  systems 
are:  (1)  Anaconda  or  oldest, 
striking  east-west  and  carrying 
important  ore  bodies.  (2)  Blue, 
earliest  fault  fissure,  striking  in 
general  N.  55°  W.,  and  carrying 
ores  of  great  value;  (3)  Moun- 
tain view  breccia  fault,  striking 
N.  75°  E.  and  carrying  ore;  (4) 
Steward,  striking  northeast- 
southwest,  and  not  usually  ore 
bearing;  (5)  Rarus  fault,  a  com- 
plex fissure  of  variable  northeast 
strike,  and  dipping  about  45° 
northwest,  with  fragmental  ore 
dragged  in  from  other  veins 
(Fig.  198,  200);  (6)  Middle 
faults,  non-orebearing;  (7)  Con- 
tinental fault,  striking  north- 
south  on  eastern  edge  of  district, 
of  recent  age,  with  1500  feet 
vertical  displacement,  and  Butte 
on  down-throw  side  (Fig.  198). 

The  granite  is  much  altered  by  hydrothermal  metamorphism, 
especially  in  the  Anaconda  Hill  area,  so  that  it  is  now  a  mass 
of  pyrite,  sericite  and  quartz  near  the  veins. 

The  ore  deposits  are  fissure  veins,  formed  by  the  filling  of  fissures 
and  replacement  of  the  country  rock,  the  oldest  fissures  having 
been  continuously  mineralized. 


596 


ECONOMIC  GEOLOGY 


Within  the  Butte  district  there  is:  (1)  A  main  or  central 
copper  zone,  free  from  zinc  and  manganese ;  (2)  An  indeterminate 
intermediate  zone,  with  copper  predominant,  and  with  some 
sphalerite,  rhodochrosite  and  rhodonite;  (3)  An  outer  peripheral 
zone,  without  copper,  but  filled  chiefly  with  quartz,  rhodonite, 
rhodochrosite,  sphalerite,  and  pyrite  and  which  is  silver  bearing. 

In  the  central  or  copper  zone,  the  order  of  relative  abundance 
of  the  copper  sulphides  is  (74);  chalcocite,  enargite,,  bornite, 
chalcopyrite,  tetrahedrite,  tennantite  and  covellite.  Quartz 
and  pyrite  form  the  gangue. 

Sales  (74)  gives  the  following  details  regarding  the  sulphides: 
Chalcocite  has  supplied  60%  of  the  Butte  copper  to  date,  occurring 


FIG.  199.  —  Longitudinal  vertical  projection  of  the  High  Ore  Vein,  a  member  of 
the  Blue  Vein  system,  showing  distribution  of  the  ore  shoots.  (After  Sales, 
Amer.  InsL  Min.  Engrs.,  XLVI.) 

in  veins  of  all  ages,  and  at  all  levels  down  to  below  3000  feet. 
Once  regarded  entirely  as  a  downward  secondary  enrichment 
product,  it  is  now  divisible  into,  (a)  sooty  secondary  chalcocite, 
forming  a  dull  black  coating  on  pyrite  and  other  sulphides  or 
replacing  pyrite,  sphalerite,  enargite  and  chalcopyrite;  (b) 
massive  chalcocite,  considered  as  primary  because:  (1)  it  is 
abundant  in  the  depest  levels  (over  3000  feet);  (2)  its  intimate 
association  with  bornite,  enargite  and  pyrite  show  it  to  be  con- 
temporaneous; (3)  it  occurs  at  all  depths  without  relation  to 
topography;  (4)  it  is  found  in  dry  veins,  at  deep  levels,  cut  by  the 
older  faults;  (5)  it  replaces  granite  at  deep  levels;  and  (6)  there 
is  no  evidence  of  present  replacement  except  in  the  sooty  material. 
Enargite  is  of  wide  vertical  and  lateral  distribution,  of  com- 
paratively old  mineralization,  and  usually  primary  but  sometimes 
secondary. 


598 


ECONOMIC   GEOLOGY 


Bornite  is  primary,  of  all  ages,  and  at  all  levels.  Chalcopyrite 
is  unimportant  and  chiefly  primary,  so  also  is  covellite. 

The  vein  outcrops  are  usually  barren  of  copper,  and  while  the 
oxidation  depth  is  variable,  it  averages  250  feet. 

In  the  silver  zone,  quartz  and  manganese  are  the  common 
gangue  materials,  the  veins  showing  on  the  surface  as  ledges  of 
manganese-stained  quartz. 


FIG.  200.  —  Plan  of  500-ft.  Level  of  Pennsylvania  Mine,  showing  effect  of  Rams 
fault  on  different  veins.     (After  Sales,  Amer.  Inst.  Min.  Engrs.,  XLVI.) 

The  Butte  ores  have  been  derived  primarily  from  igneous 
rocks,  the  quartz  porphyry  having  perhaps  opened  up  the  way 
for  the  ore-bearing  solutions,  the  elements  carried  by  the  latter 
having  included  Si02,  S,  Fe,  Cu,  Zn,  Mn,  As,  Pb,  Ca,  W,  Sb,  Ag, 
Au,  Te,  Bi,  and  K. 

In  the  central  part  of  the  area,  the  more  highly  heated  and  acid 
solutions  deposited  the  copper  ores,  while  the  zinc,  manganese 


COPPER 


599 


and  lead  were  precipitated  toward  the  periphery  where  the  tem- 
perature was  lower,  and  the  solutions  more  alkaline  from  reactions 
with  the  granite. 

In  1914  the  smelting  ores  averaged  4.97  per  cent  copper,  and 
yielded  about  28  per  cent  of  the  output,  while  the  concentrating 


FIG.  201.  —  Geologic  map  of  western  half  of  Butte  district.     (U.  S.  Geol,  Surv.) 


Silver  averaged  1.83  ounces,  and 


ores  averaged  2.04  per  cent, 
gold  .059  ounce. 

The  history  of  this  mining  camp  is  full  of  interest.  Butte  in  1864  was 
a  gold  camp,  but  difficulties  in  working  the  gravels  directed  attention  to  the 
mineral-vein  outcrops,  and  unsuccessful  attempts  were  made  to  work  their 
copper  and  silver  contents,  so  that  it  was  not  until  1875,  following  a  period  of 
quiescence,  that  the  discovery  of  rich  silver  ore  in  the  Travona  lode  revived 
the  mining  industry  of  Butte.  In  1877  several  silver  mines  were  opened,  fol- 
lowed by  others;  but  this  did  not  last  many  years,  for  with  the  drop  in  the 
price  of  silver  many  mines  closed,  although  one,  the  Bluebird,  had  produced 
2,000,000  ounces  of  silver  from  1885  to  1892. 


600  ECONOMIC   GEOLOGY 

The  copper  mines  were  worked  to  only  a  limited  extent  at  first,  and  the 
industry  did  not  assume  permanance  until  1879-1830,  when  matte  smelting 
was  introduced.  In  1881  the  Anaconda  mine,  which  was  first  worked  for 
silver,  began  to  show  rich  bodies  of  copper  ore,  and  since  then  the  output 
of  copper  has  steadily  increased,  there  being  a  number  of  large  smelting 
plants  located  at  Anaconda  and  Great  Falls. 

Globe-Miami,  Arizona  District  (35,  36,  41). — This  district 
became  well  known  through  the  Old  Dominion  mine  at  Globe, 
long  before  the  now  more  important  ores  at  Miami  were  developed. 

The  formations  include  a  pre-Cambrian  crystalline  complex, 
the  Final  schist  cut  by  granitic  intrusives.  Overlying  these 
unconformably  is  a  thick  series  of  Paleozoic  sediments  including 
conglomerates,  quartzites,  shales  and  limestones.  In  Mesozoic 
times  probably  there  followed  an  intrusion  of  diabase  and  granitic 
rocks,  and  then  after  an  erosion  interval  Tertiary  volcanics  and 
sediments,  the  Gila  conglomerate  being  prominent  among  the 
latter.  Faulting  of  both  pre-  and  post-Tertiary  age  is  known. 

Around  Miami  the  great  disseminations  of  chalcocite,  in  the 
Final  schist  near  the  Schultze  (Mesozoic)  granite  are  of  impor- 
tance. The  original  ore  was  a  sulphide  of  iron  and  copper,  which 
in  its  upper  part  has  undergone  leaching  and  oxidation,  accom- 
panied by  secondary  enrichment  of  the  ore  below.  The  section 
therefore  shows  a  leached  capping,  followed  by  an  irregular  zone 
of  oxidized  ore,  and  this  in  turn  by  a  secondary  enrichment  zone, 
showing  grains  and  stringers  of  pyrite  and  chalcopyrite  replaced 
by  chalcocite.  The  ore-bearing  solutions  are  believed  to  have 
come  from  the  Schultze  granite,  and  resulted  not  only  in  deposi- 
tion of  ore,  but  also  a  more  or  less  complete  silicification  of  the 
schist. 

These  disseminated  ores  represent  such  an  important  type  in  the 
West  to-day  that  a  few  figures  showing  their  low  grade,  extent, 
etc.,  as  explanatory  of  their  working  at  a  profit,  may  be  given. 

The  estimated  ore  reserves  of  the  Miami  Copper  Company  at 
Miami  l  on  January  1,  1915,  were  19,500,000  tons  of  sulphide 
averaging  2.4  per  cent  copper,  and  17,000,000  developed  tons, 
averaging  1.21  per  cent  copper,  also  6,000,000  tons  oxidized  or 
partly  oxidized  ore  averaging  2  per  cent  copper.  The  copper 
per  cent  in  ore  milled  averaged  2.28  per  cent.  The  mill  extrac- 
tion was  69.93  per  cent,  and  the  concentrates  contained  39.31 
per  cent  copper. 

1  The  Inspiration  Company  near  by  has  similar  deposits. 


COPPER 


601 


In  the  Globe  section  of  the  district  the  ore  bodies  occur  as  lenticular  replace- 
ments in  limestone,  and  as  fault  lodes,  or  fissure  zones  in  diabase. 

Much  of  the  limestone  ore  thus  far  extracted  has  been  oxidized,  but  that 
in  the  diabase  is  enriched  material.  Some  bodies  of  primary  ore  of  commercial 
value  have  also  been  developed.  In  1914  the  average  copper  contents  of  the 
smelting  ore  was  8.28  per  cent;  concentrating  ore  4.69  per  cent;  and  silica 
lining,  3.12  per  cent.  The  gold  and  silver  run  low,  but  are  saved. 

Mineral  Creek  or  Ray  district,  Ariz.  (42).  —  The  geology 
here  is  similar  to  that  at  Miami.  The  deposits  (Figs.  202  and  203) 


FIG.  202.  —  Vertical  section  (A  B,  Fig.  203)  showing  ore  body  in  schist,  Mineral 
Creek  district,  Arizona.     (After  Tolman,  Min.  and  Sci.  Press,  XCIV.) 

are  found  in  sedimentary  rocks  associated  with  faults  and  fissures, 
or  as  disseminations  in  the  Final  schist  and  granite,  this  second 
type  being  the  more  im- 
portant. In  1914  the  ore 
concentrated  averaged 
1.76  per  cent  copper.  At 
the  beginning  of  1915 
the  ore  reserves  were 
estimated  at  74,765,789 
tons,  averaging  2.214 
per  cent  copper. 

Another  interesting 
district  of  the  dissemi- 
nated type  is  that  of  the 
Burro  Mountains  in  New 
Mexico  (86). 

Virqilina     Va. This  FlG>  203>  —  Geologic   map   of    a  portion   of   the 

.     '      »      .    .  Mineral   Creek,   Ariz.,  copper  district.     (After 

region      is    of    interest      Totman,  xcix.) 

especially  because  of  the 

relationships  of   the  primary  sulphides   found   within  the   ore 

body. 

The  rocks  are  greenstone  and  sericitic  schists,  intruded  in  places 
by  granite  and  gabbro.     The  schists  have  been  derived  from  a 


602  ECONOMIC  GEOLOGY 

series  of  andesites  and  quartz  porphyries  with  a  preponderating 
amount  of  tuffs.  The  fissure  veins,  which  occur  in  the  chloritized 
and  epidotized  andesite,  contain  primary  bornite  and  chalcocite, 
in  a  gangue  of  quartz,  and  subordinate  calcite  or  epidote.  The 
ore-bearing  solutions  are  thought  to  have  come  from  the  granite, 


FIG.  204.  —  Quartz  vein  carrying  copper  sulphides,  between  walls  of  chloritized  and 
schistose  andesite,  Virgilina,  Va.     (H.  Ries,  photo.) 


whose  intrusion  postdates  the  development  of  schistosity  in  the 
volcanics. 

Alaska.  Copper  River  District  (23,  24) .  —  This  region,  which 
is  situated  some  distance  from  the  coast,  and  hence  difficult  of 
access,  has  been  but  little  developed,  although  transportation 
facilities  have  now  been  provided. 

The  primary  ore  is  chiefly  chalcocite  with  some  bornite  re- 
placing Triassic  limestone  near  a  greenstone.  The  ore  is  chiefly 
chalcocite,  but  other  sulphides  as  well  as  oxidized  ores  occur. 
In  the  Bonanza  mine  on  the  Chitina  River,  the  ore  consists 
of  a  solid  mass  of  chalcocite  in  limestone,  averaging  about  60  per 
cent  copper,  with  about  22  ounces  of  silver  to  the  ton. 


COPPER  603 

Foreign  Deposits. —  Among  those  which  deserve  mention  here  is  the  Ram- 
melsberg  deposit  of  the  northern  Hartz  district  of  Germany,  interesting  not 
only  historically,  but  also  because  of  its  disputed  origin.  The  ore  body  lies 
more  or  less  conformably  in  strongly  folded  Devonian  slates,  and  has  a  vari- 
able thickness.  The  ore  minerals  are  chalcopyrite,  pyrite,  arsenopyrite  and 
sphalerite  in  a  gangue  chiefly  of  barite.  Banding  is  present,  and  the  ore 
minerals  excepting  pyrite  are  drawn  out  into  streaks.  Bergeat  *  and  Klock- 
mann  2  thought  it  a  sedimentary  deposit,  while  Vogt 3  and  others  believed 
it  to  have  been  deposited  from  solutions  of  magmatic  origin.  Lindgren  and 
Irving  4  called  it  a  bedded  vein,  in  part  conformable  to  the  surrounding  slates, 
and  exhibiting  the  structure  of  a  dynamo-metamorphic  rock.  They  agreed 
with  Vogt  as  to  the  source. 

At  the  Braden  mines  in  the  Chilean  Andes,  the  ore  minerals  are  chalcopyrite, 
bornite,  magnetite  and  sphalerite,  with  toumaline,  quartz,  sericite,  epidote, 
etc.,  occurring  as  lodes  in  andesite,  at  its  contact  with  a  tuff.  The  vol- 
canics  surround  an  ancient  crater. 

Chuquicamata,  Bolivia,  remarkable  for  its  great  masses  of  brochantite  un- 
derlain by  sulphides  should  also  be  mentioned.3 

Native  Copper  Deposits. —  Deposits  of  native  copper  occur- 
ring in  basic  volcanic  rocks,  especially  those  of  basaltic  character, 
form  a  widespread  type.  They  are  not  strictly  speaking  the 
work  of  circulating  waters,  although  the  minerals  are  precipitated 
from  solution.  A  noteworthy  fact  is  the  constant  association  of 
the  copper  with  zeolites,  calcite,  quartz,  epidote,  etc.,  the  ore  and 
gangue  minerals  either  filling  the  gas  cavities  or  replacing  the  rock. 

The  igneous  rocks  are  regarded  by  many  as  the  source  of  the 
copper,  analysis  often  showing  a  small  percentage  of  this  metal, 
and  its  concentration  seems  to  be  associated  with  the  develop- 
ment of  the  zeolites,  so  that  a  theory  proving  the  origin  of  one 
must  include  the  other.  It  is  therefore  believed  by  some  that 
the  magmas  erupted  either  on  the  ocean  floor,  or  in  bodies  of 
fresh  water,  absorbed  the  water  of  these  on  cooling,  and  that  this 
on  mixing  with  magmatic  exhalations  broke  up  the  copper  silicate 
present,  changing  it  to  copper  chloride.  Iron  silicates  were 
similarly  affected.  These  chlorides  were  then  decomposed  by 
silicates  or  even  carbonates  of  lime,  yielding  native  copper,  ferric 
oxide  and  calcium  chloride  as  shown  by  the  following  reactions: 
2FeCl2+2CuCl+3CaSi03=2Cu+Fe203+3SiO2+3CaCl2. 

Widespread  as  native  copper  deposits  of  this  type  are,  they  are 
not  all  of  economic  importance.  In  North  America,  the  Michigan 

1  Erzlagerstatten,  p.  329,  1904. 

2  Berg  und  Hiittenwesen  des  Oberharzes,  1895,  p.  57. 

3  Zeitschr.  prak.  Geol.,  1894:    173. 

4Econ.  Geol.,  VI:   303,  1911.  5  Min.  Mag.,  IX:  36,  1913. 


604 


ECONOMIC  GEOLOGY 


COPPER 


605 


ones  outrank  all  others.  Some  production  has  also  been  obtained 
from  the  Triassic  traps  of  New  Jersey  (82) ,  and  from  those  on  the 
Bay  of  Fundy,  in  Nova  Scotia  (H5a).  Other  occurrences  are 
known  in  Oregon  (92a),  the  White  River  region  of  Alaska  (22), 
and  in  Arctic  Canada  (114).  In  other  countries  they  are  known 


MAP 

Of        THE 

PORTAGE     LAKE 

MINING      DISTRICT 


FIG.  207.  —  Map  of  a  portion  of  the  Michigan  copper   district,  showing  strike  cf 

lodes. 


in  New  Guinea,1  Brazil,2  the  Transbaikal,3  Norway,4  Germany, 
etc.,  but  are  not  all  productive. 

iBeck,  Lehre  v.  d.  Erzlagerstatten,  I:  345,  1909. 
SHussak,  Centrbl.  f.  Min.,  1906:   333. 
3  Beck,  Zeitschr.  prak.  Geol.,  1901:  391. 
*Ibid.,\II:   12,  1899. 


606  ECONOMIC   GEOLOGY 

Michigan  (63-68).  —  This  region,  which  was  discovered  in  1830 
by  Douglas  Houghton,  has  become  one  of  the  most  famous,  as  well 
as  one  of  the  leading,  copper-producing  districts  of  the  world. 

The  rocks  of  the  region,  known  as  the  Keweenaw  series,  consist 
of  interbedded  lava  flows,  sandstones,  and  conglomerates,  the 
latter  being  rounded  fragments  of  igneous  rocks,  mainly  reddish- 
quartz  porphyry. 

This  series  of  beds,  whose  entire  thickness  may  be  from  25,000 
to  30,000  feet,  dips  westward  (Fig.  206)  from  35  to  70  degrees, 
being  overlain  conformably  on  the  west  by  sediments,  while  on 


-.      -    . 
-  '  ' 


^  :  •••>.  :  -. 

[JSI  Copper  Ija&lAmygdaloid  fa-!"'-/  Trap 

AMYGDALOID  COPPER  LODE  IN  QUINCY  MINE 

FIG.  208.  —  Section  showing  occurrence  of  amygdaloidal  copper,  Quincy  Mine, 
Mich.     (After  Rickard,  Eng.  and  Min.  Jour.,  LXXVII.) 

the  east  they  are  faulted  up  against  the  horizontal  Potsdam  sand- 
stones. 

These  beds  form  a  belt  2  to  6  miles  wide,  which  extends  from 
Houghton  to  the  end  of  the  Keweenaw  peninsula,  and  rises  as  a 
ridge  from  400  to  800  feet  above  the  lake  (PL  LVI). 

The  ore,  which  is  native  copper,  and  is  occasionally  associated 
with  native  silver,  occurs  (1)  as  a  cement  in  the  conglomerate  of 
porphyry  pebbles,  or  replacing  the  latter,  (2)  as  a  filling  in  the 
amygdules  of  the  lava  beds  (Fig.  208),  (3)  as  masses  of  irregular 
and  often  large  size,  in  veins  with  calcite  and  zeolitic  gangue. 

The  tilting  of  the  beds  has  been  accompanied  by  some  slipping 
and  cross  faulting,  and  the  presence  of  copper  in  cross  joints  and 
slip  planes  indicates  later  deposition. 

The  veins,  which  cut  both  the  igneous  and  sedimentary  rocks, 
have  yielded  much  copper  in  former  years,  and  the  large  masses 
obtained  from  them  have  made  the  region  famous  ;  but  at  the  pres- 


608  ECONOMIC   GEOLOGY 

ent  time  most  of  the  production  comes  from  the  Calumet  conglom- 
erate, while  the  balance  comes  from  two  other  copper-bearing 
conglomerates  known  as  the  Albany  and  the  Allouez,  and  from  the 
ashbeds  and  amygdaloids,  whose  gas  cavities  are  filled  with  a  mix- 
ture of  native  copper,  calcite,  and  zeolites. 

A  curious  and  hitherto  unexplained  feature  is  the  irregular  distri- 
bution of  the  copper  in  the  different  beds,  which  may  be  due  to  the 
copper  solutions  being  directed  by  certain  joints  or  slip  planes. 
Thus  the  Calumet  conglomerate  carries  practically  no  ore  outside 
of  the  Calumet  and  Hecla  ore  shoot,  which  is  three  miles  long,  12-15 
feet  thick,  and  has  been  mined  to  a  depth  of  5000  feet. 

Various  theories  have  been  brought  forward  to  account  for  the 
origin  of  the  copper  ores  in  this  region. 

The  diabase  was  looked  upon  by  Pumpelly  as  a  possible  source 
of  the  ore,  and  since  its  extensive  alteration  was  no  doubt  accom- 
panied by  the  oxidation  of  protoxides  of  iron,  this  might  account 
for  the  reduction  of  the  copper  mineral  to  the  native  or  metallic 
condition,  it  being  known  that  ferrous  salts  may  precipitate 
metallic  copper  (1).  More  recently  Lane  (65,  66)  has  suggested 
that  originally  buried  water  has  also  been  an  important  factor 
in  concentration,  but  agrees  that  the  final  precipitation  was  by 
water  working  downward. 

Lane  has  pointed  out  that  the  mine  waters  show  a  striking 
increase  in  chlorine  with  depth,  in  fact  there  is  more  than  enough 
to  satisfy  the  sodium  present,  and  it  is  contained  in  relatively 
large  amounts  of  calcium  chloride.  Moreover,  the  molecules 
of  sodium  chloride  decrease  steadily  with  depth,  while  those  of 
calcium  chloride  increase. 

He  therefore  suggests,  and  his  views  are  backed  by  chemical 
experiments,  that  the  basalt  flows  originally  contained  small  per- 
centages of  copper ;  that  while  still  heated  they  no  doubt  absorbed 
sea  water  charged  with  sodium  chloride,  and  in  later  times  atmos- 
pheric waters  not  containing  any,  but  obtaining  it  as  they  seeped 
through  the  rocks. 

These  waters,  rich  in  NaCl,  migrated  downward,  taking  copper  in 
solution  as  copper  chloride. 

Reactions  with  the  glassy  base  or  original  minerals  of  the  volcanic 
rocks  gave  rise  to  the  formation  of  sodium  silicates,  accompanied 
by  precipitation  of  copper  and  formation  of  calcium  chloride. 
Descending  solutions  from  wide  areas  became  concentrated  along 
lines  favorable  to  underground  circulations,  and  hence  shoots  of 


COPPER  609 

relative  richness  resulted.     It  is  supposed  that  certain  faults  and 
slips  guided  these  waters. 

The  theory,  although  reasonable  and  backed  by  laboratory 
experiments  (5),  may  not  be  universally  accepted,  and  some  ob- 
servers believe  that  these  deep-seated  waters  with  their  peculiar 
composition  are  very  likely  of  magmatic  origin. 

Although  these  deposits  were  worked  in  prehistoric  times,  as  evidenced 
by  copper  implements  and  ornaments  found  in  the  mines,  the  famous  Calumet 
and  Hecla  Mine  was  not  opened  up  until  1846.  In  1847  Michigan  produced 
213  long  tons  of  the  total  United  States  production  of  300  tons  of  copper. 
Since  1863  the  annual  output  has  exceeded  1000  tons  and  gradually  and 
steadily  increased  up  to  1905,  when  it  reached  230,287,992  pounds.  Since 
that  year  it  has  only  exceeded  it  once,  and  has  usually  been  less. 

The  ores  from  this  district,  which  are  known  as  Lake  ores,1  are  all  of  low 
grade,  but  the  deposits  are  of  great  extent  and  rather  uniform  mineraliza- 
tion, and  this  fact,  together  with  the  possibility  of  high  concentration  and  low 
cost  of  refining,  makes  it  possible  to  work  these  low-grade  deposits  at  a  profit. 

The  richest  ore  now  mined  contains  under  1.5  per  cent  of  copper,  while 
the  poorest  runs  but  little  over  .5  per  cent. 

The  crushed  and  concentrated  material  carries  about  65  per  cent  copper, 
and  this  passes  through  a  combined  smelting  and  refining  process. 

That  portion  of  the  copper  which  contains  enough  silver  to  make  its 
recovery  profitable,  and  some  which  runs  too  high  in  impurities  for  certain 
uses,  is  refined  electrolytically.  The  amount  so  treated  has  been  lessened, 
owing  to  a  recent  demand  for  copper  carrying  arsenic.  The  average  re- 
covery of  silver  per  ton  of  rock  mined  was  .2  fine  ounce. 

! 
B.  Deposits  from  Meteoric  Waters s 

In  many  parts  of  the  world  there  are  low-grade  disseminated  ores  of  copper 
(chiefly  chalcocite)  in  sandstones  and  shales,  ranging  from  Carboniferous  to 
Triassic  in  age.  They  are  not  as  a  rule  sufficiently  rich  to  work,  although  the 
carbonates  on  the  surface  may  make  them  attractive  propositions  to  some. 
That  they  seem  to  have  been  concentrated  from  the  surrounding  rock  by 
meteoric  waters  is  a  commonly  accepted  view. 

This  type  of  copper  occurrence  is  widespread  in  the  Red  Beds  (Permian) 
of  the  southwest,  but  is  oi  no  economic  importance.  Similar  deposits  have 
been  worked  in  the  well-known  Corocoro  2  district  of  Bolivia,  and  in  the 
Triassic  of  England.  They  are  also  known  in  the  Permian  of  Russia  and 
Bohemia,  and  the  Triassic  of  western  Prussia. 

Reference  may  be  made  in  this  connection  to  the  famous  Mansfeld  copper 
deposits  of  Germany,  which  are  probably  of  syngenetic  nature.  These 
occur  as  minutely  disseminated  sulphides  in  Permian  shale.3 

1  The  term  has  now  lost  its  original  meaning,  since  copper  from  western  states  is 
brought  to  Michigan  for  refining  and  sold  as  Lake  ore. 

2  Vogt,  Krusch  u.  Beyschlag,  Lagerstatten,  II:  428,  1912. 

3  Bergeat,  Erzlagerstatten. 


610  ECONOMIC   GEOLOGY 

Deposits,  Usually  Lens-Shaped,  in  Crystalline  Schists. 

Scattered  over  the  world  are  a  number  of  copper  sulphide 
deposits,  often  more  or  less  lenticular  in  character,  and  occurring 
in  schistose  rocks,  which  may  be  either  igneous  or  sedimentary 
metamorphics.  Some  criticism  may  be  urged  against  grouping 
them  together,  because  their  mode  of  origin  is  admittedly  some- 
what variable,  but  otherwise  they  show  more  or  less  mineralogical 
and  structural  resemblances. 

In  general  it  may  be  said  that  they  represent  deposits  formed 
at  deep  or  intermediate  levels,  by  replacement  or  in  cavities. 
Zones  of  shearing  have  often  afforded  channel  ways  for  the 
solutions.  While  the  host  rock  is  often  a  schist,  in  other  cases  it 
may  have  been  a  limestone,  of  which  little  or  nothing  now  remains, 
so  complete  has  been  the  replacement. 

United  States.  —  Copper  deposits  in  schist  are  most  prominent 
in  the  Appalachian  belt  of  the  east,  and  in  California.  The  more 
important  ones  are  reviewed  below. 

Appalachian  States  (29,  30,  104).- — The  Appalachian  states 
contain  a  number  of  copper  deposits  in  schist  distributed  from 
Maine  to  Alabama,  but  few  of  them  are  of  commercial  importance. 

Ducktown,  Tenn.  (97-99).  —  Here  we  have  steeply  dipping 
lenses  replacing  calcareous  beds  in  folded  and  faulted  schists. 
These  lenses,  whose  exact  origin  was  not  clear  until  sufficient 
mining  had  been  done  to  furnish  the  necessary  evidence,  range 
from  a  few  feet  to  over  250  feet  in  thickness,  have  the  shapes 
and  character  of  closely  folded  sedimentary  beds.  The  ores  are 
somewhat  metamorphosed  and  the  gangue  minerals  bent.  Pri- 
mary ore  consists  of  pyrrhotite,  pyrite,  chalcopyrite,  sphalerite, 
bornite,  hematite  and  magnetite  in  a  gangue  of  calcite,  actinolite, 
tremolite,  garnet,  zoisite  and  other  silicates,  a  combination 
representing  deep-seated  conditions  and  limestone  replace- 
ment. The  gossan  of  the  different  bodies,  now  worked  out,  had 
a  maximum  thickness  of  100  feet,  and  showed  40-50  per  cent  Fe, 
under  12  per  cent  Si02  and  A^Oa,  and  .3-. 7  per  cent  Cu.  Be- 
tween the  gossan  and  dense  sulphides  there  were  found  shallow 
zones  of  rich  chalcocite. 

In  1914  the  ores  yielded  28.7  pounds  of  blister  copper  per  ton, 
or  1.435  per  cent,  with  an  average  value  of  9  cents  in  gold  and 
silver  per  ton  of  ore.  Some  of  the  copper  is  marketed  without 
electrolytic  refining.  The  massive  ore  requiring  little  timber  in 


COPPER 


611 


mining,  together  with  cheap  fuel  and  labor  costs,  have  made  it 
possible  to  work  these  low-grade  ores  at  a  profit.  Pyritic  smelting 
is  employed,  and  large  sulphuric  acid  plants  have  been  erected 
to  utilize  the  sulphur  driven  off  from  the  ores  in  roasting. 


EAST  TENNESSEE 


** 

^k  EUREKA 


BOYD/, 

/    /CULCHOTE 


OLD  TENNESSEE 


/a. 


/ 

\j?  Grajwacke  and  mica  schist 


Staurolitlc  beds 
2000  4000  Fc»t 


FIG.  209.  —  Plan  of  ore  bodies  at  Ducktown,  Tenn.     (After  W.  H.  Emmons,  U.  S. 
GeoL  Suro.,'Bull.  470.) 

Virginia-North  Carolina.  —  The  Gossan  Lead  of  southwestern 
Virginia  (104)  (Fig.  210)  and  the  copper  deposits  of  Ore  Knob, 
North  Carolina,  also  belong  to  this  type.  At  the  former  the  ore 
is  a  mixture  of  pyrrhotite  with  subordinate  chalcopyrite,  and 
admixed  quartz  and  schists.  The  vein  fills  a  fault  fracture  be- 
tween sericite  schists,  which  contains  mica,  calcite,  quartz,  and 
actinolite,  replaced  by  the  later  pyrrhotite  and  chalcopyrite  (Fig. 
211).  The  copper  content  is  low,  viz.,  .75  per  cent,  and  hence 
the  ore  is  used  for  acid  making,  but  the  residue  is  available  for 
copper. 

Arizona,  Jerome  District  (31).  —  The  ores  occur  in  a  pre-Cam- 
brian  schist,  and  consist  of  pyrite,  chalcopyrite,  some  sphalerite, 
and  varying  amounts  of  quartz,  replacing  the  schist. 


612 


ECONOMIC  GEOLOGY 


FIG.  210.  —  Map  of  Carroll  County,  Va.,  pyrrhotite  area,  showing  position  of  the 
"  Great  Gossan  Lead  "  in  heavy  black  band,  and  principal  copper  mines  located 
on  it.  Broken  lines  are  other  probable  leads.  (After  Watson  and  Weed,  Min. 
Res.  Va.) 


FlG.  211.  —  Section  of  ore  from  Chestnut  Yard,  Va.,  showing  pyrrhotite  (white) 
and  chalcopyrite  (black)  replacements  in  hornblende  (parallel  lines).  (After 
Weed  and  Watson,  Econ.  GeoL,  I.) 

The  ore  body  is  really  composed  of  a  series  of  irregular  lenses. 
Unlike  most  of  the  other  Arizona  copper  deposits,  this  ore  carries 
rather  high  gold  and  silver  values. 

California  (44,  45,  46) .  —  In  the  Klamath  Mountains  of  Shasta 
County,  there  are  important  replacement  deposits  of  pyritic  ore 
occurring  mainly  along  fissures  and  shear  zones  of  an  intrusive 


COPPER  613 

Mesozoic  alaskite  porphyry.  Two  areas  separated  by  the 
Sacramento  River  are  recognized. 

An  eastern  one,  containing  the  Bully  Hill  and  Afterthought 
districts,  with  deposits  more  vein-like,  the  ore  siliceous,  relatively 
high  in  chalcopyrite,  and  sphalerite  important.  A  western  one, 
with  more  or  less  flat,  tabular  ore  bodies,  carrying  pyrite,  some 
chalcopyrite  and  variable  sphalerite,  the  last  being  sometimes 
rich  enough  to  form  zinc  ore. 

The  gangue  is  gypsum,  calcite  and  barite,  and  while  chal- 
cocite  and  bornite  are  sometimes  found  intergrown  with  chal- 
copyrite, they  may  at  times  be  secondary.  Good  gossans  are 
found. 

Magmatic  waters  are  supposed  to  have  deposited  the  ore  in  the 
highly  sericitized  alaskite  porphyry. 

In  1914  the  average  copper  content  was  3.56  per  cent,  with 
$1.70  per  ton  of  precious  metals. 

The  so-called  Foot  Hills  belt  (46),  occupying  a  somewhat  exten- 
sive area  in  Calaveras  County,  carries  pyrite  and  chalcopyrite 
lenses  in  schistose  rocks.  The  ores  at  times  carry  considerable 
lead,  zinc  and  precious  metals. 

Alaska.  Prince  William  Sound  District  (21) .  —  In  this  district 
the  ore  is  chalcopyrite  disseminated  through  metamorphic  schists. 
The  most  important  mine  is  on  Latouche  Island,  and  here  the  ore, 
which  is  a  mixture  of  chalcopyrite,  pyrrhotite,  and  pyrite,  has 
been  deposited  mainly  as  a  cavity  filling,  less  often  as  a  replace- 
ment or  impregnation,  in  a  shear  zone  in  interbedded  slates  and 
graywackes. 

Canada  (112).  —  A  number  of  interesting  pyritic  deposits  occur 
in  the  eastern  townships  of  Quebec.  There  are  three  belts  of 
crystalline  rocks  separated  by  apparently  Paleozoic  sediments 
cut  by  intrusives,  but  some  of  the  former  prove  to  be  altered 
schistose  volcanics. 

Most  of  the  copper  deposits  are  associated  with  more  or  less 
highly  altered  schistose  volcanic  rocks,  and  while  a  few  were 
formed  by  the  impregnation  and  partial  replacement  of  limestone, 
most  of  them  have  originated  by  the  irregular  impregnation  of 
the  more  schistose  bands  along  shear  zones  in  metamorphosed 
igneous  rocks.  In  other  cases  the  replacement  of  the  schists  has 
given  rise  to  lenticular  bodies  of  ore,  which  include  some  of  the 
most  important  mines.  The  sulphides  are  chiefly  chalcopyrite 
and  pyrifce,  but  zinc  and  lead  may  occur  in  small  amounts. 


614  ECONOMIC   GEOLOGY 

Other  Foreign  Deposits.  —  Of  the  many  foreign  occurrences,  the  two  best 
known  perhaps  are  those  of  Rio  Tinto,  Spain,  and  Mount  Lyell,  Tasmania. 
The  former  occur  as  lenses,  often  of  large  size,  in  sheared  and  schistose 
porphyries  and  slates.  The  massive  pyritic  ore  carries  pyrite,  chalcopyrite, 
sphalerite  and  galena.  The  hematite  gossan,  caps  sulphides  which,  due  to 
enrichment,  carry  from  3  to  12  per  cent  copper.  The  wall  rocks,  according  to 
Finlayson,  show  hydrothermal  alteration.  Klockman  argued  for  a  sedi- 
mentary origin  l  ;  DeLaunay  regarded  them  as  veins  or  lodes  formed  by 
cavity  filling;  2  Vogt  assigned  a  pneumatolytic  origin,  following  the  por- 
phyry intrusion ; 3  while  Finlayson  believes  them  to  have  been  the  result  of 
metasomatism  by  magmatic  solutions  along  shear  zones.4 

At  Mount  Lyell  we  have  great  lenses  of  pyrite,  with  quartz  and  barite 
gangue,  occurring  chiefly  in  sericite  schists,  which  have  been  intruded  by 
porphyrites.  The  ore  carries  from  2  to  3  per  cent  copper,  due  to  a  chalco- 
pyrite content.  Large  deposits  are  also  worked  in  Russia.  5 

Uses  of  Copper.  —  Since  prehistoric  times  copper  alloyed  with 
tin  has  been  used  in  various  parts  of  the  world  for  the  manufacture 
of  bronze.  Thus  it  was  used  for  this  purpose  in  Homeric  times, 
and  it  is  found  in  the  lake  dwellings  of  Switzerland.  The  bronze 
found  in  Troy  contains  a  very  little  tin,  and  since  this  metal  is  not 
found  in  the  excavations  in  the  West,  it  seems  probable  that  the 
bronze  was  made  in  Asia,  perhaps  in  China  or  India,  by  some 
secret  process,  and  imported  to  the  western  countries. 

By  an  alloy  of  copper  and  tin,  although  both  metals  are  soft,  a 
comparatively  hard  metal  is  produced.  The  properties  of  this 
alloy,  bronze,  vary  greatly  according  to  the  proportions  of  the 
two  metallic  constituents,  and  these  vary  with  the  use  for  which  the 
alloy  is  intended.  United  States  ordnance  is  90  per  cent  copper 
and  10  per  cent  tin,  while  ordinary  bell  metal  is  about  80  per  cent 
copper,  though  the  percentage  varies  with  the  tone  required. 
Statuary  bronze  is  generally  an  alloy  of  copper,  tin,  and  zinc; 
and,  in  these  various  bronzes,  the  color  varies  from  copper-red 
to  tin-white,  passing  through  an  orange-yellow. 

An  alloy  of  copper  and  zinc  produces  brass,  which  is  found  of  so 
much  value  for  small  articles  used  in  building  and  for  ornamental 
purposes  in  machinery.  Copper  is  also  used  in  roofing  and 
plumbing. 

A  large  supply  of  this  metal  is  made  into  copper  wire,  and  the 
most  important  present  use  of  copper  is  in  electricity,  for  which  its 

^eitschr.  prak.  Geol.,  1897:    113.  3  Zeitschr.  prak.   Geol.,  1894:   241. 

2  Ann.  des  Mines.,  ser.  7,  XVI:   407.  4  Econ.  Geol.,  V:   357,  1910. 

5  Stickney,  Kyshtim  deposits,  Min.  Mag.,  XIV:  77,  1916;  also  Econ.  Geol., 
XI,  1915. 


COPPER 


615 


high  conductivity  especially  fits  it  for  the  transmission  of  electric 
currents. 

Production  of  Copper.  —  The  production  of  copper  in  the  United 
States  has  increased  steadily  and  rapidly  in  the  last  fifty  years, 
placing  the  United  States  in  the  lead  of  the  world's  copper  pro- 
ducers. This  increase  can  be  seen  from  the  following  tables: 


PRODUCTION  OF  COPPER  IN  THE  UNITED  STATES,   1910-1914,  BY  STATES, 

IN  POUNDS 


1910 

1911 

1912 

1913 

1914 

Alaska      

4,311,026 
297,250,538 
45,760,200 
9.307,497 
6,877,515 

221,462,984 

283,078,473 
3,784,609 
64,494,640 

22,022 
43 

125,185,455 

65,021 
217,127 
18,342,359 

22,314,889 
303,202,532 
35,835,651 
,9791,861 
4,514,116 

218.185,236 

271,814,491 
2,860,400 
65,561,015 

125,943 
1,607 

142,340,215 

195,503 
130,499 
20,358,791 

31,926,209 
359,322.096 
31,516,471 
7,963.520 
7.182.185 

231.112.228 

308,770,826 
29.170.400 
83.413.900 

311.860 
23,657 

132.150,052 

1,069,938 
25,080 
19,310,298 

23,423,070 
404,278,809 
32,492,265 
9,052,104 
8,711.490 

155,517,286 
576,204 
285,719,918 
50,196,881 
85,209,536 
180 
11 
77,812 
245.337 
4.549 
19.489,654 
39.008 
148.057,450 
5,771 
46,961 
732,742 

362,235 
46,803 

24,9»o,S47 
382,449,922 
29,784,173 
7,316,066 
5,875,205 
12,248 
158.009,748 
53,519 
236,805,845 
64,204,703 
60,122.904 
19,712 

5,599 
422,741 

18,661,112 
34,272 
160,589.660 

17.753 
683,602 
10,098 
17.082 

55,381 

California       

Maryland       

[Montana              

Nevada     

North  Carolina       .... 
Oklahoma      

South  Dakota    

Texas  
Utah    

Virginia    
Washington        .. 
Wisconsin      : 

Other    States    and    unappor- 
tioned   ....*.. 

Total      .     .     .     .    .     .(. 

1,080,159,509 

1,097,232,749 

1,243,268,720 

1,224,484,098 

1,150,137,192 

WORLD'S  PRODUCTION  (SMELTER  OUTPUT)  OF  COPPER  IN  1913,  IN  POUNDS 


COUNTRY 

PRODUCTION  IN 
POUNDS 

COUNTRY 

PRODUCTION  IN 
POUNDS 

Germany      .      .     .     .     , 
England       
Italy 

55,776,380 
661,380 
3  527  360 

United  States        .     .     . 
Argentina    

1,224,484,098 
220,460 
8  157  020 

Norway        

19,400,480 
8  377  480 

Chile       
Peru 

88,184,000 
56  658  220 

Russia     

74,735,940 

Venezuela    

2,865,980 

Sweden   
Spain  and  Portugal  . 
Turkey    
Servia 

2,204,600 
120,591,620 
1,102,300 
14  109  440 

Cuba       
Cape  Colony    .... 
Namaqualand 

7,495,640 
7,275,180 
5,511,500 
161  376  720 

Canada  

76,975,832 

Australia      

104,277,580 

116  402  880 

661  380 

World's  Total 

2  198  732  130 

616 


ECONOMIC  GEOLOGY 


COPPER  PRODUCED  IN  1914  FROM  ORES  IN  WHICH  COPPER  CONSTITUTES 
THE  PRINCIPAL  VALUE,  BY  STATES 


State 

Copper 
ore 

Copper 
in  ore 

Per- 
cent- 
age 

Gold 
in  ore 

Silver 
in  ore 

Value 
in  gold 
and 
silver 
per  ton 

Alaska      .     .     . 
Arizona    . 
California 
Colorado 
Idaho       .     . 
Michigan 

Short  tons. 
153,605 
7,508,020 
397,868 
12,196 
93,040 
9,269,413 

Pounds. 
21,450,628 
391,020,335 
30,507,692 
1,330,056 
4,986,206 
164,344,058 

6.64 
2.60 
3.84 
5.45 
2.68 
.89 

Fine  ounces. 
8,283.30 
50,842.80 
16,630.16 
3,243.88 
1,076.54 

Fine  ounces. 
283,355 
2,604,371 
703,042 
173,845 
239,355 
413,500 

$  2.17 
.33 
1.84 
13.38 
1.66 
.02 

Missmrrr 
Montana 
Nevada    . 
New  Mexico 
Oregon 

18 
4,346,034 
2,882,121 
2,005,024 

2,463 
231,019,109 
60,398,084 

58,878,888 

6.85 
2.66 
1.05 
1.47 

'25,422.  61 
49,476.61 
11,352.45 

14 
8,015,694 
181,733 
292,266 

.43 
1.14 
.39 

.20 

Pennsylvania  and 
Maryland 
Tennessee 
Texas       .     . 
Utah    .     .     . 
Virginia    . 
Washington 
Wisconsin 
Wyoming      . 

252,823 
653,621 
231 
7,578,220 
1,440 
21,752 
37 
78 

658,264 
18,737,656 
23,760 
142,988,221 
139,008 
746,297 
10,300 
17,421 

.13 
1.44 
5.13 
1.94 
2.05 
1.71 
13.51 
11.54 

299  .  63 

97,955  .  32 
20.76 
220.93 

97,462 
6,826 
1,726,230 
1,458 
90,574 
16 
79 

'".09 
16.32 
.39 
.86 
2.51 
.47 
.56 

Total  and  Aver. 

35,175,541 

1,127,258,546 

1.60 

264,824  .  99 

14,829,760 

.39 

COPPER  ORES  CONCENTRATED   AND   SMELTED,    CONCENTRATES    PRODUCED 
AND  COPPER  PRODUCED  FROM  EACH  CLASS  OF  ORE  IN  1914,  BY  STATES 


STATE 

ORE  CONCENTRATED 

ORE  SMELTED 

Quantity 

Concen- 
trates 
produced 

Copper  in 
concen- 
trates 

Per- 
cent- 
age 
of 
cop- 
per 
from 
ore 

Quantity 

Copper 
produced 

Per- 
cent- 
age 
of 
cop- 
per 
from 
ore 

Alaska      .     .     . 
Arizona  J 
California 
Colorado 
Idaho 
Michigan 
Missouri 
Montana  3    . 
Nevada    .     .     . 
New  Mexico 
Pennsylvania  and 
Maryland 
Tennessee     . 
Texas       .     .     . 
Utah    .... 
Virginia    . 
Washington 
Wisconsin      .     . 
Wyoming 

Total  and  Aver. 

Short 
tons. 
58,968 
5,329,245 

(2) 

68,484 
9,269,413 

3,716,347 
2,735,415 
1,917,104 

252,768 

7,'l'06,594 
13',278 

Short 
tons. 
8,144 
440,161 

Pounds. 

8,515,713 
158,932,432 

7.22 
1.49 

i!63 
.89 

2.  24 
.92 
1.39 

.13 

'  '.88 
'  '.81 

Short 
tons. 
94,637 
2,135,614 
397,868 
12,196 
24,546 

"is 

573,032 
136,005 
87,920 

55 
653,621 
231 
471,626 
1,440 
8,474 
37 
78 

Pounds. 

12,934,915 
231,103,784 
30,507,692 
1,330,056 
2,757,824 

2,463 
58,168,286 
10,016,559 
5,488,168 

12,248 
18,737,656 
23,760 
17,209,706 
139,008 
530,432 
10,300 
17,421 

6.83 
5.41 
3.84 
5.45 
5.62 

6  '.85 
5.08 
3.68 
3.12 

1.10 
1.44 
5.13 
1.82 
2.05 
3.13 
13.51 
11.54 

5,031 
132,070 

1,305,976 
445,223 
148,919 

7,659 

'  2,'2'28,382 
164,344,058 

166,352,667 
50,366,650 
53,390,820 

646,016 

360,569 
'l,486 

125,77'8',5i5 
215,865 

30,467,626 

2,855,238 

730,771,118 

1.20 

4,597,398 

389,090,278 

4.23 

1  Slag  smelted  and  ore  leached  amounted  to  43,161  tons,  containing  984,119  pounds   of 
copper. 

2  Small  quantity  of  copper  ore  concentrated  included  under  ore  smelted. 

3  Ore  leached,  56,655  tons;    eopper  from  ore  leached,  1,281,374  pounds;    copper  from 
precipitates,  5,216,782  pounds. 


COPPER 


617 


TOTAL  UNITED  STATES  IMPORTS  AND  EXPORTS  OF  COPPER,  INCLUDING  ORE, 
MATTE,  AND  REGULUS,  Pics3  BARS,  INGOTS,  PLATES,  RODS  AND  WIRE 


YEAR 

IMPORTS  IN  POUNDS 

EXPORTS  IN  POUNDS 

1912     
1913 

410,241,295 

408  778  954 

775,000,658 
926  241  092 

1914 

306  350  827 

840  080  922 

PRODUCTION  OF  COPPER  IN  CANADA  BY  PROVINCES,  1912  TO  1914 


19 

12 

19] 

3 

19 

14 

POUNDS 

VALUE 

POUNDS 

VALUE 

POUNDS 

VALUE 

Quebec     
Ontario 

3,232,210 
22  250  601 

$  536,346 
3  635  971 

3,455.887 
25  885  929 

$   527,679 
3  952  522 

4.201,497 
28  948  211 

$     571,488 
3  937  536 

British  Columbia  . 
Other  districts  l 

50,526,656 
1  772  660 

8.256,561 

239  670 

45,791,579 
1  843  530 

6,991.916 
281  489 

41,219,202 
2  i  367  050 

5,606,636 
185  946 

Total     

77  832  127 

$12718546 

76  976  925 

$11  753606 

75  735  960 

$10  301  606 

1  Includes  Nova  Scotia  and  Yukon.     2  Yukon  only. 
EXPORTS  AND  IMPORTS  OF  COPPER  IN  CANADA,  1912-1914 


YEAR 

1EXF 

ORTS 

2  IMPORTS 

Pounds 

Value 

Value 

1912    . 
1913               .      .      .      .     , 

78,488,564 
85  147  560 

$9,036,479 
9  927  814 

$7,047,356 
7  414  gio 

1914    

77,398.723 

8,270  689 

4  256  901 

1  Copper  in  ore,  matte,  etc. 


2  Pigs,  ingots,  manufactured,  etc. 


Copper  Reserves.  —  Lindgren  (5  a)  points  out  that  the  visible  copper 
reserves  of  the  United  States  are  much  larger  than  those  of  lead  ore,  and, 
moreover,  they  are  much  larger,  now,  at  the  maximum  of  production,  than 
they  have  ever  been  before,  and  yet  they  are  in  most  cases  not  nearly  so 
great  as  those  blocked  out  for  some  other  materials  like  coal.  This,  how- 
ever, is  owing  to  the  different  mode  of  occurrence  of  the  two  substances. 
The  amount  of  available  reserves  to  be  estimated  depends  on  the  market 
price  of  copper.  With  the  latter  at,  say,  20  cents  per  pound  one  can  estimate 
a  much  larger  reserve  than  if  the  price  were  only  13  cents.  Lindgren  believes 
that  the  copper  resources  of  the  United  States  are  large  enough  to  respond 
for  a  number  of  years  to  a  demand  increasing  at  the  rate  of  30,000,000 
pounds  per  annum. 

REFERENCES    ON    COPPER 

GENERAL.  1.  Butler,  Chapter  on  Copper  in  Mineral  Resources,  U.  S.  Geoi. 
Survey.  (Annual  Statistics,  etc.)  2.  Clark,  Univ.  N.  Mex.,  Bull.  75: 
77,  1914.  (Chemistry  secy,  enrich't.)  3.  Emmons,  W.  H.,  Econ.  Geol., 
IV:  755,  1909.  (Regionally  metamorphosed  ore  deposits.)  4.  Graton.. 


618  ECONOMIC  GEOLOGY 

and  Murdoch,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XLV:  26,  1913.  (Sec- 
ondary sulphides.)  5.  Fernekes,  Econ.  Geol.,  II:  580,  1907.  (Copper 
precip'n  from  chloride  sol'ns  by  ferric  chloride.)  6.  Kemp,  Econ.  Geol. 
I:  11,  1906.  (Sec'y  enrich't.)  7.  Lane,  Can.  Min.  Inst.,  XIV:  316, 

1912.  (Native  copper  deposits.)     8.  Lindgren,  Econ.  Geol.  VI:    687, 
1911.     (Copper   ores   in   basic   rocks.)     9.  Lindgren,   Econ.   Geol.   VI: 
568,    1911.     (Copper  in  sandstones   and  shales.)     10.  Lindgren,   U.   S. 
Geol.  Surv.,  Bull.  394:    131,   1909.     (Copper  ore  reserves.)     11.  Pos- 
njak,  Allen  and  Merwin,  Econ.  Geol.,  X:    491,   1915.     (Sulphides  of 
copper.)     12.  Rogers,    Min.   and    Sci.   Pr.,    CIX:    680,    1914.     (Sec'y 
enrich't.)     13.  Thompson,    Econ.    Geol.,  IX:    171,    1914.     (RePn  pyr- 
rhotite  and  chalcopyrite  to  other  sulphides.)     14.  Spencer,  Econ.  Geol., 
VIII:    621,   1913.     (Chalcocite  enrich't.)     15.  Stevens,  Copper  Hand- 
book.    Published  annually  by  W.  H.  Weed,  New    York.     16.  Stokes, 
Econ.  Geol.,  I:    644,  1906.     (Sol'n  transport'n,  dep'n  of  copper.)     17. 
Tolman,  Amer.  Inst.  Min.  Engrs.,  Bull.,  Feb.,  1916:    401.     (Types  of 
Chalcocite,  etc.)     18.  Tolman  and  Clark,  Econ.  Geol.,  IX:    559,  1914. 
(Chemistry  of  copper    sulphide  dep'n.)     19.  Tolman  and  Clark,  Min. 
and    Sci.    Pr.,    CVIII:     172,    1914.     (Sulphide    enrich't.)     20.  Weed, 
Copper  Mines  of  the  World,  New  York. 

AREAL  PAPERS.  Alaska:  21.  Johnson,  U.  S.  Geol.  Surv.,  Bull.  592:  237, 
1914.  (Pr.  Wm.  Sound.)  22.  Knopf,  Econ.  Geol.,  V:  247,  1910. 
(Native  copper,  White  River.)  23.  Lincoln,  Econ.  Geol.,  IV:  201,  1909. 
(Big  Bonanza  Mine.)  24.  Moffit  and  Madden,  U.  S.  Geol.  Surv.,  Bull. 
374,  1909.  (Kotsina-Chitina.)  25.  Smith,  P.  S.,  U.  S.  Geol.  Surv., 
Bull.  592:  75,  1914.  (Ketchikan.)  26.  Wright,  C.  W.,  U.  S.  GeoL 
Surv.,  Prof.  Pap.  87,  1915.  (Copper  Mtn.)  27.  Wright,  C.  W.,  Econ. 
Geol.,  Ill:  410,  1908.  (Kasaari  Peninsula.)  28.  Wright,  F.  E.,  and 
Wright,  C.  W.,  U.  S.  Geol.  Surv.,  Bull.  347,  1908.  (Ketchikan.)  Appa- 
lachian States:  29.  Emmons,  U.  S.  Geol.  Surv.,  Bull.  432,  1910.  (Me. 
and  N.  H.)  30.  Weed,  U.  S.  Geol.  Surv.,  Bull.  455,  1911;  Amer. 
Inst.  Min.  Engrs.  Trans.,  XXX:  454,  1901.  Arizona:  31.  Graton, 
U.S.  Geol.  Surv.,  Min.  Res.  1907,  Pt.  I:  597,  1908.  (United  Verde.) 
32.  Jenney,  Eng.  and  Min.  Jour.,  XCVII:  467,  1914.  (Porphyry  ores, 
Bisbee.)  33.  Lindgren,  U.  S.  Geol.  Surv.,  Prof.  Pap.  43,  1905.  (Clif- 
ton-Morenci.)  34.  Ransome,  U.  S.  Geol.  Surv.,  Prof.  Pap.  21,  1904. 
(Bisbee.)  35.  Ransome,  Ibid.,  Prof.  Pap.  12,  1903;  also  Min.  and  Sci. 
Pr.,  C:  256,  1910  andCII:  747,  1911.  (Globe.)  36.  Ransome,  U.  S. 
Geol.  Surv.,  Bull.  529:  183,  1913.  (Globe.)  37.  Ransome,  Ibid., 
Bull.  529;  179,  1913.  (Bisbee.)  38.  Ransome,  Ibid.,  Bull.  529  :192, 

1913.  (United   Verde.)     39.  Ransome,    Ibid.,    Bull.   540:    139,    1914. 
(Superior.)     40.   Stewart,     Amer.     Inst.    Min.    Engrs.,    XLIII:    240, 
1913.     (Silver  Bell.)     41.  Tovote,  Min.  and  Sci.    Pr.,  CVIII:    442  and 
487,  1914.     (Globe    district.)     42.  Weed,  Min.    Wld.,   XXXIV:     153, 
1911.     (Ray.)      California:    43.    Aubury,     Calif.     State     Min.     Bur., 
Bull.  23,  1902.     (General.)     44.  Boyle,  Amer.  Inst.  Min.  Engrs.,  Trans., 
XLVIII:  67,  1915.     (Bully  Hill.)     45.  Graton,  U.  S.  Geol.  Surv.,  Bull. 
430:    71,  1910.     (Shasta  Co.)     46.  Knopf,    Calif.  Univ.  Dept.    Geol., 
Bull.  IV:  411.     (Foothills  belt.)     47.  Reid,  Econ.  Geol.,  II:  380,  1907. 


COPPER  619 

(Copperopolis.)  48.  Turner  and  Rogers,  Econ.  GeoL,  IX:  359,  1914. 
(Plumas  Co.)  49.  Bagg,  Econ.  GeoL,  III:  739,  1908.  (Sangre  de 
Christo  Range.)  Colorado:  50.  Bastin  and  Hill,  Econ.  GeoL,  VI:  465, 
1911.  (Gilpin  Co.)  51.  Emmons,  S.  F.,  U.  S.  GeoL  Surv.,  Bull.  260, 
1905.  (Copper  in  Red  Beds.)  52.  Emmons,  W.  H.,  U.  S.  GeoL  Surv. 
Bull.  285,  1906.  (Cashin  Mine,  Montrose  Co.)  53.  Lindgren,  U.  S. 
GeoL  Surv.,  Bull.  340,  1908.  (Chaff ee,  Fremont  and  Jefferson  Cos.)  54. 
Spencer,  U.  S.  GeoL  Surv.,  Bull.  213:  163,  1903.  (Pearl,  Colo.) 
Georgia:  55.  Watson,  U.  S.  GeoL  Surv.,  Bull.  225,  1904.  (Seminole 
copper  deposits.)  Idaho:  56.  Calkins  and  Jones,  U.  S.  GeoL  Surv., 
Bull.  540:  167,  1914.  (Mullan.)  57.  Collier,  U.  S.  GeoL  Surv.,  Bull. 
285,  1906.  (St.  Joe  River  basin.)  58.  Gale,  U.  S.  GeoL  Surv.,  Bull. 
430,  1910.  (Montpelier,  Bear  Lake  Co.)  59.  Kemp,  Amer.  Inst.  Min. 
Engrs.,  Trans.,  XXXVIII:  269,  1908.  (White  Knob.)  60.  Lindgren, 
Min.  and  Sci.  Pr.,  LXXVIII:  125,  1899.  (Seven  Devils.)  61.  Ransome 
and  Calkins,  U.  S.  GeoL  Surv.,  Prof.  Pap.  62:  150,  1908.  (Cceur 
d'Alene.)  Maryland:  62.  Butler  and  McCaskey,  Amer.  Inst.  Min. 
Engrs.,  XLIX:  284,  1915.  (New  London  Mine.)  Overbeck,  Econ. 
GeoL,  XI:  151,  1916.  (Metallographic  study.)  Michigan:  63. 
Grout,  Econ.  GeoL,  V:  471,  1910.  (Keweenawan  copper.)  64. 
Irving,  R.  D.,  U.  S.  GeoL  Surv.,  Mon.  V.  1885.  65.  Lane,  Mich. 
GeoL  Surv.,  GeoL  ser.  4,  Vols.  I  and  II,  1911  66.  Lane,  Can.  Min. 
Inst.  Quart.,  Bull.  7,  1909.  (Copper  mine  waters.)  67.  Rickard, 
Eng.  and  Min.  Jour.,  LXXVIII:  585,  625,  665,  745,  785,  865, 
905,  1025,  1904.  -  (Historic  and  geologic.)  68.  Van  Hise  and  Leith, 
U.  S.  GeoL  Surv.,  Mon.  LII:  573,  1911.  Missouri:  69.  Bain  and 
Ulrich,  U.  S.  GeoL  Surv.,  Bull.  267,  1905.  (General.)  Montana: 

70.  Bard,   Amer.   Inst.   Min.   Engrs.,   XLVI,    1914.     (Butte  minerals.) 

71.  Kirk.  Econ.   GeoL,   VII:    35,    1912.      (Alter'n   wall   rock,  Butte.) 

72.  Ray,  Econ.  GeoL,  IX:    463,  1914.     (Paragenesis  Butte  minerals.) 

73.  Rogers,  Econ.  GeoL,  VIII:  781,  1913.     Ref.  117,  Chap.  XIV.     (Up- 
ward  sulphide  enrich.,    Butte.)     74.   Sales,   Amer.   Inst.   Min.   Engrs. 
XLVI,  1914.     (Gen'l  on  Butte.)     75.  Sales,  Econ.  GeoL,  V:    15,  1910. 
(Superficial  alter'n,  Butte.)     76.  Weed,  U.  S.  GeoL  Surv.,  Prof.  Pap. 

74.  1912.     (Butte.)     77.  Winchell,    Eng.    and    Min.   Jour.,    LXXXV: 
782,  1903.     (Chalcocite  synthesis.)     Nevada:   78.  Carpenter,  Min.  and 
Sci.  Pr.,  CI:    4,   1910.     (Yerington.)     79.  Lawson,  Cal.  Univ.  Dept. 
GeoL,  Bull.  4:    284.     (Ely.)     80.  Ransome,  U.  S.  GeoL  Surv.,  Bull. 
380:  99,  1909.     (Yerington.)     81.  Spencer,  Ibid.,  Bull.  529:   189,  1913. 
(Ely.)    New  Jersey:   82.  Lewis,  N.  J.  GeoL  Surv.,  Ann.  Rept.,  1907:   131, 
1908.     New  Mexico:  83.  Ball,  Min.  and  Sci.  Pr.,  July  26,  1913.     (Sand- 
stone  deposits,  Bent.)     84.  Lindgren,  Graton  and  Gordon,  U.  S.  GeoL 
Surv.,    Prof.   Pap.   68:    305,    1910.     (Santa   Rita.)     85.  Paige,    Econ, 
GeoL,    VII:     547,    1912.      (Santa   Rita,    Chino.)      86.  Somers,    Amer, 
Inst.   Min.  Engrs.,  Bull.   101:    958,    1915.     (Burro  Mts.)     87.  Paige, 
U.  S.  GeoL  Surv.,  Bull.  470,   1911.     (Burro  Mts.)     North  Carolina; 
88.  Laney,    Econ.    GeoL,    VI:     399,     1911.     (Virgilina.)     89.  Laney, 
N.  Ca.  GeoL  Surv.,  Bull.  21,  1910.     (Gold  Hill  district.)     90.  Pogue' 
Ibid.,    Bull.  22,   1910.     (Cid  district.)     91.  Weed,  Amer.   Inst.   Min 


620  ECONOMIC   GEOLOGY 

Engrs.,  Trans.,  XXX:  449.  (Types  of  deposits.)  Oklahoma:  92. 
Tarr,  W.  A.,  Econ.  GeoL,  V:  221,  1910.  (Copper  in  Red  Beds.)  92a. 
Lindgren,U.S.Geol.Surv.,'22Ann.  Rept.,Pt.2:  551,  1901.  Pennsylvania: 

93.  Bailey,  Eng.  and  Min.  Jour.,  XXXV:-    88,    1883.     (Adams  Co.) 

94.  Bevier,  Top  and  GeoL  Com.  Kept.,  July,  1914.     (South  Mountain.) 

95.  Lyman,  Jour.  Frank.  Inst.,  CXLVI:  416,  1898.     (Bucks  and  Mont- 
gomery counties.)     96.  Stose,  U.  S.  GeoL  Surv.,  Bull.  430,  1910.     (So. 
Mtn.)     Tennessee:   97.  Emmons  and   Laney,  U.  S.  GeoL  Surv.,  Bull. 
470;v  151,   1911.     (Ducktown.)     98.  Kemp,  Amer.  Inst.  Min.  Engrs., 
Trans.,  XXX]  ^224,  1901.     (Ducktown.)     99.  Weed,  U.  S.  GeoL  Surv., 
Bull.  455:  152,  *1911.    Texas:  100.    Phillips,  Eng.  and  Min.  Jour.,  XCII: 
1181,    1911.    (Permian   ores.)     Utah:    101.   Beeson,  Amer.   Inst.  Min. 
Engrs.,  Bull.  107:  2191,  1915.     (Bingham.)     102.  Boutwell,  U.  S.  GeoL 
Surv.,  Prof.  Pap.  38:    1905.    (Bingham.)     103.  Butler,  U.  S.  GeoL  Surv., 
Prof.  Pap.  80,  1913f  also  Econ.  GeoL  IX:  413  and  529,  1914.     (San 
Francisco  district.)    Virginia:  104.  Watson,  Min.  Res.  Va.,  1907.     (Va.) 
105.    Weed  and  Watson,  Econ.  GeoL,  I:  309,  1906.    (Va.)    106.  Watson, 
GeoL  Soc.  Amer.,  Bull.  XIII:    353,  1902.     107.  Laney,  Econ.    GeoL, 
VI:    399,  1911.     (Virgilina.)     Washington:    108.  Weaver,  Wash.  GeoL 
Surv.,   Bull.   7,    1912.     (Index.)     Wisconsin:     109.  Grant,   Wis.   GeoL 
and  Nat.  Hist.  Surv.,  Bull.  9,  1903.     (Douglas  Co.)     Wyoming:    110, 
Ball,  U.  S.  GeoL  Surv.,  Bull.  315,  1907.     (Hartville.)     111.  Spencer. 
Ibid.,   Prof.   Pap.   25,    1904.     (Encampment   district.)     Canada:     112, 
Bancroft,  Dept.  Col'n,  Mines  and  Fisheries,  Mines  Branch,  Que.,  1913. 
(Quebec.)     113.  Clapp  and  Cooke,  Can.  GeoL  Surv.,  Summ.  Rep.,  1913: 
84,  1914.     (Vancouver  Is.)     114.  Douglas,  Can.  Min.  Inst.,  XVI:    83, 
1914.     (Native    copper,    Arctic.)     115.  Drysdale,    Can.    GeoL    Surv., 
Mem.   77,    1916.      (Rossland.)      115a.  Ells,    Can.    GeoL    Surv.,    Min. 
Res.,  1904.     (N.  S.,  N.  B.,  Que.)     116.  Le  Roy,  Can.  GeoL  Surv.,  Mem. 
21,  1912.     (Phoenix.)     117.  Le  Roy,  Ibid.,  Mem.  19,   1913.     (Mother 
Lode.)     118.  McConnell,  Can.  GeoL  Surv.,  Mem.  58,  1914.     (Texada 
Is.)     119.  Cairnes,  Internat.  GeoL  Congr.,  Can.,   1913,  Guidebook  of 
Excursions,  No.  10.     (White  Horse.)     120.  Stewart,  Min.  and  Sci.  Pr., 
CV,  107,  1912.     (South  belt,  Rossland.) 

See   also   Annual   Reports,    Minister  of   Mines,    British   Columbia, 
especially  Rept.  for  1914:  143  for  Granby  Bay. 


CHAPTER  XVII 


LEAD   AND    ZINC 

IT  is  usually  customary  to  treat  these  two  ores  together  for  the 
reason  that  they  are  so  frequently  associated  with  each  other,  but  it 
must  not  be  understood  from  this  that  they  are  found  free  from 
association  with  other  metals,  as  in  the  Rocky  Mountain  region  for 
example,  gold,  silver,  or  copper  may  often  occur  with  them,  forming 
ores  of  somewhat  complex  character. 

The  silver-lead  ores  form  a  somewhat  distinct  class  and  are  treated 
separately. 

Ore  Minerals  of  Zinc.  —  The  zinc-ore  minerals,  together  with  the 
percentage  of  zinc  which  they  contain,  are : — 


Sphalerite  (Isometric)  . 
Wurtzite  (Hexagonal)  . 
Smithsonite  .... 
Calamine 

ZnS 
ZnS 
ZnCO3 
2  ZnO  SiO2  H2O 

67 
67 
51.96 
542 

Hydrozincite  .... 
Zincite  

ZnCO3,2Zn(OH)2 
ZnO 

60 
803 

Willemite  
Franklinite  .... 

2ZnO,SiO2 
(FeMnZn)0,(FeMn)2O3 

58.5 
variable 

Of  these  ores,  sphalerite  (also  known  as  blende,  jack,  rosin  jack,  or 
black  jack)  is  by  far  the  most  important,  except  in  northern  New  Jersey, 
where  it  is  practically  lacking  and  franklinite  and  willemite  abound. 

Sphalerite  may  be  either  a  primary  or  secondary  ore  mineral.  Wurzite  has 
been  noted  in  some  of  the  Missouri  ores  and  also  foreign  ones,  indeed,  many 
massive  blendes  may  be  a  mixture  of  sphalerite  and  wurtzite.1 

Blende  is  often  associated  with  other  sulphides,  especially  galena,  pyrite, 
and  marcasite,  but  more  rarely  chalcopyrite. 

Smithsonite,  found  in  the  oxidized  zone,  is  a  comparatively  rare  ore 
mineral  in  the  United  States,  although  it  is  an  important  one  in  Europe. 
Calamine,  also  an  oxidized  ore  mineral,  is  far  more  abundant,  and  found 
in  many  deposits.  Both  Smithsonite  and  calamine  may  occur  in  a  pure 
and  crystalline  form,  but  more  often  they  are  quite  impure,-  of  crusted  or 
earthy  character  and  are  usually  intimately  associated.  Hydrozincite  is  not 
uncommon  in  some  districts. 

1  J.  Noelting,  Zeit.  Kryst.  u.  Min.,  XVII:   220,  1890. 
621 


622  ECONOMIC   GEOLOGY 

Ore  Minerals  of  Lead.  —  The  lead-ore  minerals,  together  with 
their  composition  and  the  percentage  of  lead  which  they  contain, 
are:  — 


Galena 

PbS 

864 

Cerussite 

PbCO3 

77  5 

Anglesite 

PbSO4 

683 

Pyromorphits  .... 

Pb3P208  +  ^PbCl2 

76.36 

There  are  a  vast  number  of  lead  minerals  in  addition  to  the  above, 
but  they  have  little  or  no  commercial  value  on  account  of  their  rarity. 

Of  the  above-named  ore  minerals  galena  is  the  commonest,  and  may 
be  of  either  primary  or  secondary  character.  It  frequently,  especially  in 
the  complex  ores,  carries  variable  amounts  of  silver.  The  other  three 
lead-ore  minerals  are  usually  found  in  the  oxidized  zone,  and  the  cerussite 
is  not  uncommon,  but  the  sulphate  when  formed  usually  changes  to  the 
carbonate. 

The  lead  and  zinc  ores  may  be  divided  into  three  groups  as  follows : 

(1)  lead  and  zinc  ores,  practically  free  from  copper  and  the  precious 
metals;  (2)  lead  and  zinc  ores,  canying  more  or  less  gold  and  silver, 
as  well  as  some  iron  and  copper;  and  (3)  lead-silver  ores. 

In  the  first  group  iron  and  manganese  are  not  uncommon  im- 
purities, and  those  of  southwestern  Missouri  contain  small 
amounts  of  cadmium;  but  this  is  not  injurious,  as  it  is  more 
volatile  than  the  zinc  and  easily  driven  off.  Calcite,  dolomite 
and  pyrite  or  marcasite  are  common  gangue  minerals,  and  barite 
or  fluorite  may  occur  at  certain  localities. 

In  the  United  States  the  ores  of  the  second  group  are  found 
chiefly  in  the  Rocky  Mountain  region,1  and  are  not  only  of  com- 
plex character,  but  differ  in  their  form  and  origin  from  most  of 
the  eastern  ones.  Quartz  is  probably  the  commonest  gangue 
mineral,  but  there  may  be  other  less  important  ones.  Antimony, 
arsenic,  and  iron  may  be  among  the  impurities. 

The  silver-lead  ores,  found  in  many  of  the  western  states, 
carry  silver  and  lead  as  their  chief  metals,  but  may  contain  smaller 
amounts  of  zinc,  gold,  or  iron.  They  show  a  preference  for  lime- 
stone. 

Mode  of  Occurrence.  —  Zinc  and  lead  ores  may  occur  under 
a  variety  of  conditions,  viz.:  (1)  as  true  metalliferous  veins; 

(2)  as  irregular  masses  in  metamorphic  rocks;    (3)  as  irregular 

1  Exceptions  are  some  Louisa  and  Spottsylvania  County  deposits  of  Virginia, 
and  the  Cid  district  of  North  Carolina. 


LEAD  AND  ZINC  623 

masses  or  disseminations,  formed  by  replacement  or  impregna- 
tion in  limestones  or  quartzites;  (4)  in  contact-metamorphic 
deposits;  (5)  in  cavities  not  of  the  fissure- vein  type;  and  (6)  in 
residual  clays. 

Mode  of  Origin.  — While  both  lead  and  zinc  may  form  under 
a  variety  of  conditions,  they  are  not  found  in  commercial  quantities 
in  igneous  rocks  including  pegmatites.  Occurrences  of  workable 
character  of  one  or  the  other  are  found  in:  (1)  contact 
metamorphic  deposits;  (2)  deeper  zone  veins;  (3)  intermediate 
depth  veins;  and  (4)  in  sedimentary  rocks,  unassociated  genetic- 
ally with  igneous  ones,  and  concentrated  by  meteoric  circulation. 
The  third  and  fourth  are  the  most  important,  and  veins  of  the 
third  often  contain  gold,  silver,  and  copper,  but  these  are  treated 
in  the  next  two  chapters. 

Neither  lea'd  nor  zinc  ores  are  restricted  to  any  one  formation, 
but  the  majority  of  economically  valuable  deposits  of  these  metals, 
without  silver,  gold,  or  copper,  are  found  in  the  Paleozoic  forma- 
tions, although  a  few  are  known  in  pre-Cambrian  and  Triassic 
(Silesia)  rocks. 

While  the  metallic  content  of  the  ore  as  mined  is  often  low,  still, 
owing  to  the  great,  difference  in  gravity  between  ore  and  gangue 
minerals  (excepting  pyrite  or  marcasite  and  blende),  it  is  often 
possible  to  separate  them  by  mechanical  concentration;  and  for 
the  zinc  ores  magnetic  separation  has  been  successfully  tried. 

Superficial  Alteration  of  Lead  and  Zinc  Ores.  —  Galena  is 
often  altered  near  the  surface  to  anglesite  or  cerussite.  The 
former,  however,  is  unstable  in  the  presence  of  carbonated  waters 
and  changes  readily  to  the  carbonate.  Phosphates  are  developed 
in  rare  instances. 

Sphalerite,  the  common  ore  cf  zinc,  is  often  changed  super- 
ficially to  smithsonite,  hydrozincite,  or  calamine.  Such  oxidized 
ores  are  of  greater  value  than  unoxidized  ones,  because,  although 
carrying  a  lower  percentage  of  zinc,  they  occur  in  a  more 
concentrated  form  and  yield  more  easily  to  metallurgical  treat- 
ment. 

The  chemical  changes  involved  in  the  weathering  of  lead  ores 
are  probably  simple,  but  those  of  zinc  are  more  complex  than  was 
formerly  thought  (3).  They  are  given  on  p.  489. 

Galena  is  more  resistant  to  weathering  and  solution  than 
sphalerite,  hence  when  associated  in  the  same  deposit,  galena  is 
often  found  in  the  oxidized  zone  while  sphalerite  is  removed. 


624 


ECONOMIC   GEOLOGY 


The  soluble  compounds  produced  by  weathering  may  be  car- 
ried down  below  the  water  level  and  reprecipitated  as  sulphides 
(see  reactions,  p.  485),  but  authentic  cases  of  secondary  zinc  and 
lead  sulphides  are  rare. 

Distribution  of  Lead  and  Zinc  Ores  in  the  United  States. — 
The  general  distribution  of  lead  and  zinc  ores  is  shown  on  the  map, 
Fig.  212.  Deposits  of  lead  alone  are  found  in  the  Appalachian 
belt,  and  southeastern  Missouri.  With  the  former  there  are  also 
a  number  of  small  veins  in  metamorphic  rocks  from  Maine  to 
Georgia,  but  with  the  exception  of  some  of  the  Virginia  occur- 


FlG. 


212.  —  Map  showing  distribution  of  lead  and  zinc  ores  in  the  United  States. 
(Adapted  from  Ransome,  Min.  Mag.,  X.) 


rences,  they  are  of  little  importance.  Zinc  ores,  almost  free  from 
lead,  occur  in  New  Jersey,  the  Virginia  Tennessee  belt,  the  Saucon 
Valley,  Pennsylvania  and  southwestern  Missouri.  Lead  and  zinc 
together,  free  from  gold,  silver,  or  copper  are  prominent  in  the 
Upper  Mississippi  Valley.  The  mixed  ores  are  prominent  in  the 
Cordilleran  region. 

Desilverized  Lead.1  —  The  important  localities  supplying  this 
type  of  lead  are  described  under  lead-silver  ores,  but  brief  refer- 
ence may  be  made  to  them  here.  Idaho  is  the  most  important 
prducer,  most  of  the  ore  coming  from  the  Cceur  d'Alene  district. 
In  Utah  much  is  obtained  from  the  Park  City  district  of  Summit 

1  This  term  is  applied  to  those  occurrences  of  lead  associated  with  silver.  In  the 
smelting  of  the  ore,  the  two  metals  are  separated. 


1200       0     1000    2000    3000    4000  ft.^ 


GEOLOGIC  CROSS  SECTIONS 

SCALE   OF   FEET 
0  000  1200 


Cambrian  Limestone    Franklin  Limestone 
and  Quartzite  (white  crystalline 

(.blue  limestone)  limestone) 

GEOLOGIC  MAP  OF  FRANKLIN  FURNACE  AND  VICINITY 
WITH  SECTIONS  OF  THE  ZINC  ORE  BODIES 


Outcrop  of  Zinc        Magnetite  Outcrop 
Ore  Bodies 


PLATE  LVII.  —  Geologic  map  of  Franklin  Furnace  and  vicinity,  with  sections  of 
the  zinc-ore  bodies.     (After  Spencer,  N.  J.  Geol.  Surv.) 

(Q25) 


626 


ECONOMIC   GEOLOGY 


County,  the  Bingham  Canon  and  Cottonwood  districts  of  Salt 
Lake  County,  and  the  Tintic  district  of  Juab  County.  Colorado's 
main  supply  is  yielded  by  the  Leadville  mines  in  Lake  County 
and  the  Aspen  mines  of  Fitkin  County,  while  smaller  amounts  are 
obtained  from  Creede,  Lake  City,  Ouray,  and  Rico.  (See  Lead- 
Silver  references.) 

Comparatively  little  lead  is  produced  in  the  western  states, 
except  in  the  three  mentioned  above.  The  important  lead  ores 
of  this  region  being  closely  associated  with  both  igneous  and 
feedimentary  rocks. 

Most  of  the  zinc  obtained  in  the  Rocky  Mountain  states  is 
from  complex  ores.  Leadville  is  the  most  important  producer, 
and  is  described  below  together  with  some  others  of  minor  im- 
portance. ' 

Contact-Metamorphic   Deposits 

United  States.  —  Few  undoubted  deposits  of  this  type  are 
known.  Magdalena,  N.  Mex.  (42).  —  At  this  locality  faulted 


FIG.  213.  —  Model  of  Franklin  zinc-ore   body.     (After  Nason,  Amer.  Inst.   Min. 
Engrs.,  Trans.  XXIV.) 

blocks  of  Paleozoic  limestone  have  been  cut  by  granite-porphyry 
dikes,  the  former  containing  roughly  lenticular  ore  bodies,  which 
in  their  oxidized  zone  yield  lead,  silver  and  zinc,  while  in  the 
sulphide  zone  the  ore  carries  much  sphalerite  with  a  little  galena 
and  chalcopyrite.  Magnetite  and  specularite  are  present,  whi^e 
the  gangue  has  abundant  epidote,  pyroxene  and  tremolite,  but 
little  garnet. 

Sussex  County,  New  Jersey  (39-41) . — The  output  of  these  mines 
is  second  in  importance  to  those  of  Mississippi  Valley  region. 


LEAD  AND   ZINC  627 

The  district  (PL  LVII)  includes  two  general  areas  situated  close 
together,  the  one  called  Mine  Hill,  at  Franklin,  and  the  other 
called  Sterling  Hill,  at  Ogdensburg,  two  miles  farther  south. 

The  ore  deposits  are  in  white  crystalline  limestone,  which  is 
bounded  on  the  northwest  by  gneiss,  and  on  the  southeast  by  blue 
Cambrian  limestone  along  a  fault  line. 

At  Mine  Hill  (Fig.  213)  the  northerly  pitching  ore  body  lies  in 
the  white  limestone  adjacent  to  its  contact  with  the  gneiss,  and  has 
the  shape  of  a  trough,  whose  southern  end  appears  to  be  doubled 
over  into  an  anticline.  Magnetite  deposits  outcrop  locally  along 
the  limestone-gneiss  contact,  both  adjacent  to  the  zinc  deposit, 
and  for  a  distance  of  more  than  one-half  mile  to  the  southwest. 

The  Sterling  Hill  (Fig.  214)  deposit  at  Ogdensburg  lies  away  from 
the  limestone-gneiss  contact.  The  ore  body  is  also  a  trough,  which 


FIG.  214.  —  Plan  of  outcrop  and  workings  of  the  Sterling  Hill  ore  body.     (After 
Spencer,  N.  J.  GeoL  Sure.,  Ann.  Rept.,  1908.) 


pitches  towards  the  east,  and  has  a  hook-like  outcrop.  Both 
sides  of  the  trough  dip  southeast;  the  exact  extent  of  this  ore 
body  is  not  known. 

The  ore  minerals  are  principally  franklinite,  willemite  (often 
somewhat  manganiferous) ,  and  zincite.  These,  together  with 
tephroite,  are  practically  the  only  metallic  minerals  at  Sterling 
Hill;  but  in  the  Mine  Hill  deposits,  . several  other  zinc-  and 
manganese-bearing  minerals,  mainly  silicates,  are  not  uncommon. 
Sphalerite  occurs  sparingly. 

The  gangue  minerals  are  calcite,  rhodonite,  garnet,  pyroxene,  and 
hornblende.  The  ore  is  granular,  and  some  of  it  shows  strong  foli- 


628  ECONOMIC   GEOLOGY 

ation.  There  is  usually  a  gradation  from  ore  into  country  rock, 
arid  while  the  ore  appears  to  show  a  lamination  corresponding  with 
that  of  the  gneisses,  the  three  dominant  ore  minerals  mentioned  are 
not  evenly  mixed  in  all  parts  of  the  ore  body. 

At  Mine  Hill  the  run  of  mine  ore  has  been  estimated  to  contain  from 
19  to  22.5  per  cent  iron,  6  to  12  per  cent  manganese,  27  per  cent  zinc. 

The  franklinite  has  been  found  to  contain  from  39  to  47  per  cent  iron, 
10  to  19  per  cent  manganese,  and  6  to  18  per  cent  zinc ;  the  willemite  from 
1.5  to  3  per  cent  each  of  iron  and  manganese  ;  and  the  zincite  about  5  per 
cent  manganese  and  iron. 

At  Sterling  Hill  the  limestone  lying  between  the  outcropping  ends 
of  the  sides  of  the  trough  is  mineralized,  while  inside  the  trough  of 
ore  there  is  a  curved  dike  of  hornblendic  pegmatite,  and  on  the  con- 
vex side  of  the  dike,  towards  the  ore,  there  are  occasional  develop- 
ments of  garnet,  zinciferous  pyroxene,  and  biotite. 

We  have  in  this  district  two  zinc  deposits,  which  are  quite  different 
from  all  other  known  deposits  of  this  metal,  not  only  because  of  the 
association  of  iron,  manganese,  and  zinc  in  such  ore  bodies,  but  also 
because  of  the  form  of  combination  of  the  zinc  ores.  Thus  we  have 
the  oxides  franklinite  and  zincite,  together  with  the  silicate  willemite, 
occurring  in  great  abundance,  although  very  rare  elsewhere. 

The  origin  of  these  deposits  is  of  unusual  interest,  for  they  not 
only  contain  in  abundance  a  number  of  zinc  minerals,  rare  or  un- 
known elsewhere,  but  many  other  mineral  species  as  well. 

Kemp  (39)  considers  that  the  ore  was  probably  deposited  by 
solutions  stimulated  by  intrusions  of  granite,  and  subsequently 
metamorphosed,  but  Wolff  (41)  suggests  that  they  are  contem- 
poraneous in  form  and  structure  with  the  inclosing  limestones  and 
hence  older  than  the  granites. 

Spencer  (40)  argues  that  the  present  characters  of  the  ore  masses 
and  wall  rocks  originated  contemporaneously  because  the  two  are 
not  sharply  separated;  so  that  the  deposits  must  have  been  intro- 
duced either  before  or  during  the  metamorphism  of  the  containing 
rocks  and  the  igneous  rocks  which  are  now  gneisses.  He  favors 
the  view  that  the  lean  ore  of  Sterling  Hill  was  probably  deposited 
by  magmatic  waters  which  permeated  and  replaced  the  limestone, 
and  while  the  richer  ore  may  have  been  formed  in  the  same  way, 
there  is  also  the  possibility  that  the  main  ore  layer  at  Sterling  Hill 
and  the  mass  of  ore  at  Mine  Hill  were  injected  bodily  into  the  lime- 
stones, like  igneous  intrusions. 

The  pegmatites  are  evidently  the  source  of  many  of  the  rarer 


LEAD  AND   ZINC  629 

minerals  found  in  these  deposits,  because  they  are  closely  asso- 
ciated with  them. 

While  the  origin  of  these  deposits  has  undoubtedly  been  a 
puzzling  problem,  one  is  forced  to  admit  that  it  is  perhaps  as  well 
to  class  them  as  contact-metamorphic  deposits,  a  view  held  by 
both  Vogt  and  Lindgren. 

These  ore  bodies  are  of  some  historic  interest,  having  been  prospected 
as  early  as  1640  and  mined  in  1774.  The  Mine  Hill  deposits  were  worked 
for  iron  ore  as  early. as  the  beginning  of  the  last  century,  the  zinc  mining 
having  begun  about  1840. 

The  Sussex  County  ores,  while  chiefly  valuable  as  a  source  of  zinc,  are 
likewise  of  importance  because  of  their  iron  and  manganese  contents. 

Three  products,  viz.  spelter,  zinc  oxide,  and  spiegeleisen,  are  made 
from  them. 

The  Mine  Hill  ores  >are  now  treated  by  magnetic  separators,  which 
yield  three  products,  as  follows:  1.  Mainly  franklinite,  used  in  prepara- 
tion of  zinc  white,  the  residuum  from  this  going  to  blast  furnace  to  make 
spiegeleisen.  2.  Half  and  half,  containing  franklinite,  rhodonite,  garnet, 
and  other  silicates  with  attached  particles  of  the  richer  zinc  minerals. 
This  contains  a  little  more  zinc  than  the  franklinite,  and  while  it  can  be 
used  for  zinc  white,  the  residuum  is  too  high  in  silica  for  the  spiegeleisen 
furnaces.  3.  Willemite  product,  which  consists  of  willemite  and  zincite, 
with  calcite  and  silicates  as  impurities.  The  calcite  is  removed  in  jigs 
and  on  concentrating  tables,  leaving  material  adapted  to  manufacture  of 
high-grade  spelter  free  from  lead  or  cadmium. 

The  dust  from  the  crushing  and  concentrating  plant  is  also  saved  for 
making  zinc  oxide.  The  following  gives  the  approximate  percentage  of 
each  product  and  its  zinc  contents. 

PRODUCTS  OF  MILL  AT  FRANKLIN  FURNACE 


PER  CENT  OF  EACH 

PER  CENT  OF  ZINC 

Franklinite      

49 

22 

Half  and  Half     

12 

24 

Dust 

4 

27 

Willemite 

25 

48 

Calcite  

10 

5 

loo 

High-Temperature  Veins 

The  only  representative  of  this  class  described  from  the  United 
States  is  found  as  veins  in  the  Boulder  batholith  southwest  of 
Helena.  The  ore  is  chiefly  galena,  associated  with  sphalerite  and 
pyrite.  Tourmaline  is  a  characteristic  feature. 


630 


ECONOMIC   GEOLOGY 


Deposits  Formed  at  Intermediate  Depths 

United  States.  —  Most  of  the  deposits  of  this  type  found  in  the 
United  States  carrying  lead  or  zinc,  contain  sufficient  gold  or 
silver  to  be  classed  with  the  silver-lead  (p.  658)  or  gold-silver  ores 
(p.  675).  The  most  prominent  example  deserving  notice  in  this 
chapter  is  that  of  Leadville,  Colo.,  but  in  recent  years  large  quan- 
tities of  blende  have  been  obtained  from  Butte,  Mont.  (See 
under  Copper),  and  considerable  zinc  also  comes  from  the  Coeur 
d'Alene,  Idaho, .district.  (See  under  Silver-Lead.) 
Leadville  District,  Colorado  (6-12).  —  This  region  lies  on  the 
western  side  of  the  Mosquito  Range  at  the 
headwaters  of  the  Arkansas  River  in  south- 
central  Colorado,  while  the  town  of  Lead- 
ville is  situated  on  the  western  spurs  of  the 
range  overlooking  the  Arkansas  Valley.  The 
latter  is  bounded  by  the  Sawatch  Range  on 
the  west. 

The  mines  which  have  made  Leadville 
famous  for  its  production  of  silver,  gold,  lead, 
zinc,  iron,  and  manganese  are  mostly  high 
up  on  the  ridge  and  from  2  to  3  miles  east 
of  the  town,  but  in  later  3rears  developments 
have  been  spreading  westward  towards  the 
valley.  The  district  was  formerly  placed 
among  the  lead-silver  camps,  but  since  the 
rich  bodies  of  silver-bearing  lead  carbonate 
have  become  exhausted  a  large  tonnage  is 
obtained  from  the  lead-zinc  sulphide  ore 
bodies  deeper  down,  and  for  that  reason  it 
is  placed  here,  although  it  is  not  to  be  under- 
stood from  this  that  other  metals  are  not 
produced  there  in  quantity. 

The  Sawatch  Range  is  an  oval  mass  of 
gneisses,  granites,  and  schists  on  whose  flanks 
rest  the  Cambrian  and  later  sediments,  dip- 
ping away  from  the  range  on  all  sides. 

The  Mosquito  Range  (elevation  13,000  to 
14,000  feet)  is  composed  mainly  of  Paleozoic 
rocks,  with  some  Mesozoic  deposits  on  its 
eastern  flanks,  while  between  these  beds  are 


PLATE  LVIII 


FIG.  1.  —  View  from  top  of  Carbonate  Hill,  Leadville,  Col.,  looking  towards  Iron 
Hill.  The  valley  in  center  ground  marks  position  of  the  Iron  fault.  Shaft  house 
is  that  of  Tucson  shaft,  and  ridge  in  distance  fault  scarp  of  Mosquito  Range. 
(H.  Ries,  photo.) 


FIG.  2.  —  View  from  south  end  of  Carbonate  Hill,  Leadville,  Colo.,  overlooking 
California  Gulch  in  foreground,  and  town  of  Leadville  in  the  valley.  Sawatch 
Range  in  distance.  (H.  Ries,  photo.) 

(631) 


632 


ECONOMIC   GEOLOGY 


sills  and  laccoliths  of  igneous  rocks,  whose  intrusions  occurred  be- 
fore the  uplift  of  the  region. 

This  uplift  was  formed  by  an  east-to-west  thrust  which  pushed 
the  beds  up  into  folds  against  the  Sawatch  Range  and  later  faulted 
them  (Fig.  215). 

Inconsequence,  therefore,  of  folding,  faulting,  igneous  intrusions, 
and  detrital  material,  the  structural  geology  of  Leadville  affords  a 
somewhat  complex  problem. 

The  geological  section  best  shown  in  Carbonate  Hill  perhaps  is 
as  follows :  — 


LOCAL  NAME 

AGE 

ROCKS 

THICKNESS, 
FEET 

White  porphyry  . 

Pre-Cretaceous 

White       rhyolite 

800 

porphyry 

Blue  limestone 

Lower  Carboniferous 

Blue-gray      dolo- 

200 

mite 

I  Gray  porphyry     . 

Pre-Cretaceous 

Gray    monzonite 

50 

porphyry 

Parting  quartzite 
White  limestone 

Devonian 
Silurian 

Coarse  quartzite 
Drab        siliceous 

30 
160 

dolomite  lime- 

stone 

Lower  quartzite 

Cambrian 

Mostly         white 

160 

quartzite 

Granite 

Basement     complex 

f~r  T**l  Tl  1  i"  P     Q  Yl  f\ 

of     pre-  Cambrian 

VJidJ-lltt?     ctllLL 

gneiss 

age 

The  fracturing  and  displacement  of  these  rocks  has  resulted  in  the 
formation  of  a  number  of  great  fault  blocks,  which  in  their  eroded 
form  stand  out  as  prominent  hills,  known  as  Breece,  Iron,  Carbonate, 
Fryer,  etc.  (Fig.  215). 

The  ore  bodies  occur  mainly  as  great  replacement  masses  in  the 
blue  and  white  limestones,  and  in  the  Devonian  quartzite;  but  in 
addition  there  have  been  discovered  fissures  and  cavities  in  the 
Cambrian  quartzite  (6)  which  carry  ore  that  has  evidently  been 
deposited  from  solution  and  not  by  replacement  (Fig.  216). 
While  these  fissures  are  known  to  be  connected  with  the  Silurian 
limestone  ores,  they  have  not  yet  been  traced  to  the  granite. 
Later,  however,  other  fissures  were  discovered  leading  into  the 
granite  porphyry  (9). 

Gold  ores  are  found  on  Breece  Hill  to  the  eastward,  but  these 
belong  to  a  different  type. 

The  original  ore  of  the  district  consisted  of  lead,  zinc,  iron,  and 


LEAD  AND   ZINC 


633 


copper  sulphides  carrying  silver  and  gold,  the  proportions  of  the 
several  metals  varying  in  different  parts  of  the  district. 

For  some  years  the  oxidized  ore  bodies  of  cerussite  and  cerar- 
gyrite  in  a  matrix  of  iron  and  manganese  oxide  formed  the  main- 
stay of  the  camp,  but  the  practical  exhaustion  of  these  led  to 
deeper  mining  and  the  discovery  of  the  large  sulphide  bodies  at 
lower  levels. 

A 


&&tt££K&a^  rr^rn 

+Vl+afI+t4J+X+x+JJ^a.^I4X     ,   •    Blue 

mtimm L— 


FIG.  216.  —  Vertical  section  along  line  AB,  Fig.  186.     Tucson  shaft,  Leadville,  Col. 
(After  Argall,  Eng.  and  Min.  Jour.,  LXXXIX.) 

While  the  sulphide  ores  became  an  important  source  of  supply, 
still,  as  late  as  1911  (7,  9)  there  were  discovered  in  the  blue  and 
also  white  limestone  great  quantities  of  zinc  carbonate  of  replace- 
ment origin.  P.  Argall  has  also  noted  the  presence  of  great 
masses  of  manganiferous  siderite  in  the  limestone  associated  with 
intrusive  gray  porphyries  (8). 

The  camp  now  is  turning  out  a  large  tonnage  of  lead  and 
zinc  sulphides  which  may  carry  gold  and  silver,  zinc  carbonate, 
manganese  ores  from  oxidized  deposits  on  Carbonate  Hill,  some 
copper  sulphides,  and  some  bismuth  ores. 


634 


ECONOMIC  GEOLOGY 


The  origin  of  these  ores  has  been  discussed  by  several  geologists, 
Emmons  and  Blow  being  among  the  earlier  ones. 

Emmons,  in  his  classic  monograph  on  this  district  (4)  expressed 


GEOLOGICAL  PLAN 

ON  PLANE  OF 

5TH  LEVEL 


FIG.  217.  —  Geologic  plan  of  fifth  level  and  workings,  Tucson  shaft,  Leadville,  Col. 
(After  Argall,  Eng.  and  Min.  Jour.,  LXXXIX.) 

the  following  views  regarding  the  origin  of  the  ore  deposits:  (1)  that 
they  have  been  derived  from  aqueous  solution ;  (2)  that  this  solu- 
tion came  from  above ;  (3)  that  the  ores  derived  their  metall; c  con- 
tents from  the  neighboring  eruptive  rock.  He  further  adds  that 


LEAD   AND   ZIXC 


635 


quartzite    (Figs. 


these  statements  are  not  intended  to  deny  the  possibility  that  the 
metals  may  have  originally  come  from  depth,  nor  to  maintain  that 
they  were  necessarily  derived  entirely  from  eruptive  rocks  at  present 
in  immediate  contact  with  the  deposit.  (4)  The  ores  were  deposited 
by  replacement  of  the  country  rock.  (5)  They  are  of  later  age  than 
the  porphyry  sheets,  but  were  introduced  before  the  faulting  of  the 
region  occurred. 

These  views  are  not  agreed  to  entirely  by  all  persons  familiar 
with  the  district,  and  there  is  a  tendency  among  many  engineers 
who  have   a  more   or    less 
intimate  knowledge  of  the 
region  to  feel  that  the  ores 
may  have  been  brought  in 
by  solutions  ascending  di- 
rectly from  the  granite,    a 
theory  which  they  regard  as 
being  strengthened  by  the 
finding  of  fissure  ores  in  the 
Cambrian 
216,  218). 

-ITT  i  f         A    pyrite  and  blende;  B,  galena;  C,  mud  deposit: 

We   must   remember,    of         pDy  open  cavity .  Ei  Qujrtzite; 
course,  that  since  Emmons'  FIG   218._Cavities  in  Cambrian  quaptaite( 

Work  Was  done   the   district        Tucson  shaf t,  Leadv.lle.Col.    (After  Argall.) 

has  been  greatly  and  more 

deeply  developed,  thus  affording  apportunity  for  more  extended 

investigation. 

The  plan  l  (shown  at  the  top  of  page  636)  shows  graphically 
the  course  of  treatment  of  Leadville  ores  from  mine  to  market. 

The  quantity  of  the  several  classes  of  ore  produced  in  1914  was: 
Siliceous  gold-silver  ores,  33,000  short  tons;  sulphide  ores, 
307,559  short  tons;  oxide  ores,  192,143  short  tons,  of  which 
113,881  were  zinc  carbonate. 

Even  in  former  years  Leadville  was  a  mining  camp  of  great  importance, 
having  indeed  given  Colorado  its  first  serious  start  as  a  mining  state.  From 
an  area  of  about  a  square  mile  the  output  of  silver  was  for  a  number  of  years 
greater  than  that  of  any  foreign  country  except  Mexico,  and  during  the 
same  period  the  production  of  lead  was  nearly  equal  to  that  of  England  and 
greater  than  that  of  any  European  country  excepting  Spain  and  Germany. 
Although  regarded  originally  as  a  silver  camp,  it  really  ceased  being  such 
nearly  fifteen  years  ago,  and  is  now  an  important  producer  of  at  least  eight 

1  From  U.  S.  Geol.  Surv.,  Min.  Res.,  1911. 


636 


ECONOMIC  GEOLOGY 


Mine  MouCh 
1  .1 


Mine  Mouth 

Old  Wet 

'  ^ 


Mine  Mouth 


Mine  Mouth 

Jl 


Mine  Moufll 


ine  M 


Spelter  and  zinc 
oxide  markets 


iriched  lead  furnace  matte  (40-45$  copper) 

I 

Copper  refineries 


East0rn.refineries 


metals,  of  which  five  or  six  are  sometimes  all  obtained  from  the  same  group 
of  properties.  It  will  thus  be  seen  that  the  successful  marketing  of  one  may 
affect  all  the  others.  Leadville  began  as  a  gold  camp  in  1860,  when  a  placer 
deposit  of  gold  was  found  in  a  gulch  near  there  and  several  million  dollars' 
worth  of  metal  were  extracted,  resulting  in  the  establishment  of  a  flourishing 
town  called  Oro,  which,  however,  soon  lost  its  importance  when  the  gold 
began  to  be  exhausted.  Not  until  1875  was  the  carbonate  of  lead,  which  has 
since  been  so  important,  actually  recognized. 

Deposits  Formed  Near  Surface  1 

United  States.  —  Several  ore  districts  of  the  west  may  be 
referred  to  under  this  head.  Thus  certain  veins  of  the  Lake  City 
district  carry  considerable  galena  and  zinc  in  a  quartz  gangue 
(1  la),  and  cut  volcanic  rocks.  Again  in  the  Creede  district  of 
Colorado  there  are  found  fissure  veins  in  rhyolite,  also  showing 
lead  and  zinc  with  a  gangue  of  quartz,  barite  and  fluorite  (10a). 
Others  carrying  a  stronger  content  of  the  noble  metals  are  referred 
to  under  Lead-Silver  and  Gold-Silver. 


Deposits  in  Sedimentary  Rocks,  Unrelated  to  Igneous  Ones 

Deposits  of  lead  and  zinc  in  sedimentary  rocks,  and  showing 
no  relationship  to  igneous  rocks  form  a  widely  distributed  type, 
whose  association  with  calcareous  rocks,  as  limestones,  dolomites 
and  calcareous  shales  is  most  pronounced. 

1  These  localities  are  not  strictly  lead-zinc  producers. 


PLATE  LIX 


FIG.  1.  —  View  of  valley  at  Austinville,  Va.     Zinc  ores  in  hill  at  left,  white  heap 
of  mill  tailings  on  right.     (H.  Ries,  photo.) 


FIG.  2.  —  Old  oxidized  ore  workings  at  Austinville,  Va.  The  ore  was  in  residual 
clay  which  formerly  covered  these  limestone  pinnacles.  Sulphides  underlie 
these.  (H.  Ries,  photo.) 

(637) 


638 


ECONOMIC   GEOLOGY 


The  primary  ore  minerals  are  galena  and  blende,  while  above 
them  in  the  weathered  zone  are  the  usual  oxidation  products. 
Iron  sulphide  may  often  be  present,  and  is  undesirable,  but 
gold  and  antimony  are  rare,  and  the  deposits  are  with  few  ex- 
ceptions non-argentiferous.  The  blende  may  contain  small 
quantities  of  cadmium,  or  the  latter  as  the  sulphide,  green- 
ockite  may  be  present  as  a  secondary  mineral.  Nickel  and 
cobalt  are  found  in  small  amounts  in  the  southeastern  Missouri 
ores.  Dolomite  is  a  common  gangue  mineral,  and  chert  is  often 
present. 

The  deposits,  which  are  not  of  great  depth,  may  fill  solution 
cavities,  fault  fissures,  or  form  disseminations. 

Most  geologists  believe  that  the  ore  bodies  of  this  type  have 
been  formed  by  meteoric  circulation. 

United  States.  —  In  the  United  States  this  type  of  ore  deposits 
is  especially  important  in  the  Mississippi  Valley  region,  and  also 
in  southwestern  Virginia  and  east  Tennessee. 

Virginia-Tennessee  Belt  (50-53,59).  —  Zinc  and  some  lead  oc- 
cur in  a  belt  extending  from  southwest  Virginia  into  Tennessee. 


FIG.  219.  —  Section  of  Bertha  zinc  mines,  Wythe  Co.,  Va.,  showing  irregular  sur- 
face of  limestone  covered  by  residual  clay-bearing  ore.  (After  Case,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXII.}  Compared  with  Plate  LIX,  Fig.  2. 

The  ores  are  intimately  associated  with  Cambro-Ordovician 
limestone,  and  show  two  types,  viz. :  (1)  secondary  or  weathered 
ores,  including  calamine,  smithsonite,  and  cerussite,  which 
are  concentrated  in  the  residual  clays  next  to  the  irregular 
weathered  surface  of  the  limestone  (Fig.  219  and  LIX,  Fig.  2) ; 
and  (2)  primary  ores,  including  sphalerite,  galena,  and  some 
pyrite,  belonging  to  the  disseminated  replacement  breccia 


LEAD  AND   ZINC 


639 


type  (Fig.  220),  and  which  have  been  localized  by  ground  waters 
along  the  crushed  and  faulted  axes  of  the  folds.     The  gangue  miner- 


J'IG.  220.  —  Section  showing  replacement  of  limestone  by  sphalerite  and  galena, 
Austin  ville,  Va.     (After  Watson,   Va.  Geol.  Surv.,  Bull.  I,  1905.) 


•als  are  chiefly  calcite,  dolomite,  and  some  barite.     Fluorite  is  known, 
and  quartz  may  occur  in  the  form  of  chert.     One  deposit  only,  in 

Albemarle  County,  is 
found  in  schist,  and  is 
closely  associated  with 
igneous  rocks. 

Pennsylvania  (48,  49). 
-  The  Saucon  Valley 
deposits  promised  at  one 
time  to  become  promi- 
nent producers,  but  have 
not,  owing  more  to  geo- 
logical conditions  than 
actual  scarcity  of  ore. 

Mississippi  Valley 
Lead  and  Zinc  Region. 
—  This  region  contains 


FIG.  221.  —  Map  of  Ozark  region.     (After  Bratut 
Eng.  and  Min.  Jour.,  LXXIII.) 


er,    several    somewhat    Sepa- 
ated  ^  Q£  deposits> 

viz.:  (1)  the  Ozark  Region,  (2)  upper  Mississippi  Valley  area, 
(3)  outlying  districts,  chiefly  in  northern  Arkansas,  Kentucky 
and  Illinois.  Of  these  the  first  is  the  most  important. 

Ozark  Region  (5,  23,  27-36).  —  This  region,  which  lies  mostly  in 


ECONOMIC  GEOLOGY 


Missouri  (Fig.  221),  but  also  in- 
cludes portions  of  Arkansas,  has 
four  districts,  viz.:  (1)  the  south- 
western Missouri,  which  is  essen- 
tially lead-producing,  and  has  been 
described  on  an  earlier  page;  (2) 
the  Central  Missouri,  containing 
small  ore  bodies  with  both  lead  and 
zinc  (28) ;  (3)  the  Missouri-Kansas, 
or  southwestern  Missouri,  mainly  a 
zinc-producing  area;  (4)  northern 
Arkansas  (l,  2),  producing  chiefly 
zinc,  with  some  lead. 

The  third,  or  most  important 
one,  will  be  specially  referred  to. 

The  Ozark  uplift  or  plateau  is  a 
low,  rudely  elliptical  dome  (Figs. 
222,  223) ,  lying  mostly  in  southern 
Missouri  and  northern  Arkansas. 
The  Boston  Mountains  form  the 
southern  boundary,  while  it  merges 
into  prairie  on  the  west  and  north, 
and  the  Gulf  Plains  on  the  east  and 
southeast. 

The  rocks  are  mostly  of  sediment- 
ary origin,  but  pre-Cambrian  gran- 
ites and  porphyry  form  some  of  the 
peaks  of  the  St.  Francis  Mountains. 
The  Cambrian  and  Cambro-Ordo- 
vician  dolomites,  and  limestone  and 
sandstones  underlying  the  central 
Ozark  area,  surround  these  moun- 
tains concentrically,  and  are  in  turn 
flanked  successively  by  Devonian 
to  Pennsylvanian  rocks. 

Joplin  Area  (27,31-34).  --This 
is  the  most  important  area  in  the 
o  Missouri-Kansas  district,  and  the 
3  generalized  geological  succession  is 
g  shown  in  the  accompanying  diagram 
*  (Fig.  224). 


\ 


LEAD  AND    ZINC 


641 


The  ore  deposits  of  the  Joplin  district  occur  in  large  but  very 
irregular  masses  of  chert  and  limestone,  which  are  unusually  brec- 
ciated  and  cemented  by,  or  impreganted  with,  dolomite,  jasperoid, 


FORMATION 


CHARACTER  OF  ROCKS 


Cherokee 


-UNCONFORMITY 


Carterville 

UNCONFORMITY 

(  Short  Creek 
oolite  member,) 


Boone 


(Grand  Falls 
chert  member.) 


Drab  to  black  shale  and  gray  to 
buff  sandstone  with  occasional 
beds  of  coal. 


Light  to  dark  shales  and  shaly 
and  oolitic  limestone  with 
some  massive  soft  to  hard 
sandstones, 


Massive  homogeneous  bed  of 
oolitic  limestone. 


Limestone,  in  large  part  crystal- 
line, with  interbedded  chert. 


Heavy -bedded,  solid  cherL 


FIG.  224. — Generalized  geologic  section  of  the  Joplin  district. 

Ail.  FoL  148.) 


(U.  S.  Geol  Surv., 


clacite  or  sphalerite,  and  carry  considerable  amounts  of  sphalerite, 
galena,  and  iron  sulphide.  Of  subordinate  importance  are  chalco- 
oyrite,  greenockite,  barite  and  other  minerals.  Weathering  devel- 
ps  oxides,  carbonates,  sulphates,  and  silicates  of  many  of  the 
above.  They  are  found  in  the  Boone  formation  and  show  a  close 
association  with  certain  forms  of  fracturing  and  brecciation. 

Jasperoid,  which  is  the  commonest  gangue  material,  forms  a 
cement  of  chert,  breccias  or  intercalations  in  practically  undis- 


642 


ECONOMIC   GEOLOGY 


turbed  beds  in  sheet  ground;  it  is  usually  of  a  dark  gray  to 
nearly  black  color  when  fresh,  and  the  microscope  shows  it  to  be  a 
fine-grained  allotriomorphic  aggregate  of  quartz  (Fig.  225).  Some 
have  thought  it  to  be  a  mud-like  deposit  that  was  later  silicified, 
but  it  is  more  probably  a  siliceous  replacement  of  limestone. 


FIG.  225.  —  Photo-micrograph  of  jasperoid,  showing  fine  granular  aggregate  of 
quartz,  with  sphalerite  (shaded)  and  dolomite,  the  latter  including  minute  quartz 
crystals.  X  53.  (After  Smith  and  SiebenthaL) 

The  two  important  forms  of  ore  body  are  runs  and  sheet  ground. 

The  runs  are  irregular,  usually  elongated,  and  in  places  tabular 
and  inclined  bodies  of  ore,  associated  with  breccias  produced,  ac- 
cording to  Smith,  by  minor  faulting.  They  may  be  10-50  ft.  wide, 
and  are  comparatively  shallow.  It  is  thought  they  represent  ore 
deposition  in  sink  holes  formed  in  the  upper  part  of  the  Boone 
formation  (Fig.  224) ,  during  a  period  of  pre-Pennsylvanian  erosion. 

Sheet  ground  deposits,  which  occur  in  the  Grand  Falls  chert 
member  of  the  Boone  formation  are  tabular  ore  bodies,  often 
of  great  lateral  extent,  and  6  to  15  feet  thick.  The  sulphides  occur 
in  part  along  bedding  planes  of  cherts  and  in  part  in  breccias 
resulting  from  slight  folding  and  faulting  of  the  bedded  rocks. 
In  the  breccias  the  ore  occurs  as  a  cement  or  in  jasperoid,  while 
in  the  bedding  planes  it  is  in  solution  cavities  or  in  jasperoid. 

The  sheet  ground  averages  Icr^er  in  ore  content  than  the  runs,  but 
is  more  uniform  in  character  and  being  all  at  one  level  is  more  easily  mined 


PLATE  LX 


FIG.  1.  —  View  in  Joplin  district  near  Webb  City,  Mo.     (Photo  from  F,  C.  Wai- 
lower.) 


FIG.  2.  —  Chambers  in  Disbrow  Mine,  near  Webb  City,  Mo.     These  include  both 
sheet  ground  and  the    "  broken  ground  "  above.     (Photo  from  F.  C.  Wai- 

(643) 


644  ECONOMIC   GEOLOGY 

Ore  running  6  per  cent  is  regarded  as  good,  but  when  it  falls  to  2i  per  cent 
it  hardly  pays  to  work  it. 

In  the  runs  the  galena  is  most  abundant  above,  while  the  sphalerite 
occurs  in  the  middle  or  lower  portion,  but  in  the  sheet  ground  there  is  no 
such  vertical  separation. 

The  Joplin  district  is  a  most  important  producer  of  zinc,  and  while 
the  content  of  this  metal  is  low  in  the  ore  as  it  comes  from  the  mines, 
still  concentration  raises  it  to  about  58  per  cent.  The  average  tenor  of 
lead  is  .5  to  1  per  cent  and  of  iron  from  1  to  2  per  cent.  It  assays  about 
30  per  cent  sulphur,  and  the  remainder,  besides  a  little  cadmium,  is  silica. 

An  analysis  representing  the  average  of  3800  carloads  of  blende  shipped 
from  the  Joplin  district  in  the  first  part  of  1904  is  given  by  Ingalls  as : 
Zn,  58.26 ;  Cd,  .304 ;  Pb,  .70 ;  Fe,  2.23 ;  Mn,  .01 ;  Cu,  .049 ;  CaCO3, 
1.88;  MgCO3,  .85;  SiO2,  3.95;  BaSO4,  .82;  S,  30.72;  total  99.773. 

Origin  of  the  Ores.  —  Most  of  the  theories  of  the  origin  of  these  ores 
agree  in  considering  that  their  concentration  has  been  caused  by 
circulating  meteoric  waters  which  have  collected  the  ore  particles 
from  the  limestones,  although  in  one  instance  at  least  they  were 
thought  to  be  associated  with  igneous  intrusions  (35). 

Analyses  of  the  limestones  (36)  show  amounts  of  from  .001  to 
.015  per  cent  of  lead  and  zinc  in  the  Cambro-Silurian  magnesian 
limestones  and  Archaean  rocks  in  the  southeastern  part  of  the 
Ozark  region,  and  from  .002  to  .003  per  cent  in  the  Lower  Car- 
boniferous limestones. 

These  averages,  expressed  in  different  form,  give  87  pounds  of 
galena  per  acre  in  a  one-foot  layer,  and  261  pounds  of  blende  in  the 
same  volume  of  rock. 

The  most  detailed  study  of  the  genesis  of  these  ores  has  been 
made  by  Siebenthal  (33).  He  points  out  that  the  erosion  of  the 
Pennsylvanian  shale  from  the  central  portion  of  the  uplift  exposed 
the  Cambro-Ordovician  and  Mississippian  rocks,  down  the  dip  of 
which  the  surface  waters  flowed,  and  ascended  again  on  the  inner 
margin  of  the  Pennsylvania  shale  which  still  covered  the  flanks 
of  the  uplift.  This  water  charged  with  carbon  dioxide  took  the 
sulphides  into  solution  as  bi carbonates.  As  the  solutions  rose  in 
the  broken,  cavernous  ground  in  the  Mississippian  limestones,  the 
CO2  escaped  and  the  metals  were  precipitated  as  sulphides  by  the 
hydrogen  sulphide  still  remaining  in  solution. 

There  has  been  some  difference  of  opinion  among  geologists  who  have 
studied  these  ores  in  the  past,  and  therefore  a  brief  resume"  of  these  views  is  of 
interest  partly  because  they  indicate  what  varied  conceptions  may  be  based 
on  the  same  evidence. 

A.  Schmidt l  believed  that  dolomitization  of  the  cherty  limestones  caused 
1  Mo.  Geol.  Surv.,  I,  1873-1874, 


LEAD  AND  ZINC  645 

a  shrinkage  of  the  rock,  and  was  accompanied  by  a  deposition  of  the  ore. 
Subsequent  solution  of  the  limestone  caused  a  collapse  of  the  residual  chert, 
followed  by  further  deposition  of  ore. 

Haworth  l  suggested  that  after  the  chert  and  limestone  were  greatly 
fractured  and  dislocated,  the  sulphides  were  deposited,  but  that  the  deposition 
of  secondary  chert  had  begun  before  sulphide  deposition  ceased. 

Winslow  (36)  thought  that  the  breccia-filled  caverns  in  the  country  rocks 
were  formed  by  the  percolation  of  surface  waters,  and  that  the  metalliferous 
minerals  were  leached  out  of  the  overlying  rocks  by  surface  solutions  and 
deposited  in  the  breccias. 

Jenney  (31),  however,  believes  the  ores  to  have  been  deposited  by  ascend- 
ing solutions. 

Bain  and  Van  Hise  (27)  after  studying  the  district  concluded  that  both 
ascending  and  descending  waters  were  active.  They  also  expressed  the 
view  that  while  the  more  important  circulations  have  occurred  in  the  Cam- 
bro-Silurian  limestones  and  those  of  the  Mississippian  or  Lower  Carbonifer- 
ous series,  still  the  concentration  process  has  been  often  repeated  in  many 
different  horizons  and  at  different  depths. 

According  to  their  theory,  then,  the  chemical  changes  which  took  place 
in  the  primary  concentration  of  the  ores  were  the  oxidation  of  sulphides 
(in  the  limestones)  to  sulphates,  the  transportation  of  these  in  solution, 
and  their  reprecipitation  as  sulphides  in  favorable  localities.  The  localiza- 
tion of  the  ore  bodies  has  been  due  to  the  presence  of  fissures  which  permitted 
the  mixing  of  the  ore-bearing  solutions,  but  the  circulation  of  the  latter  has 
been  limited  in  many  instances  by  impervious  beds  of  shale,  and  organic 
matter  has  served  as  a  reducing  agent. 

In  the  section  presented  in  the  Ozark  region,  the  Devono-Carboniferous 
shales  and  the  undifferentiated  Carboniferous  shales  afforded  impermeable 
barriers  to  circulation.  The  former,  where  not  faulted,  held  down  the  ascend- 
ing solutions;  but  where  absent  or  fissured,  the  solutions  from  the  under- 
lying Cambro-Silurian  formation  were  able  to  pass  upward  into  the  Mis- 
sisippian  and  impregnate  them. 

The  Cambro-Silurian  ores  were  first  concentrated  by  deep  circulation, 
and  formed  the  disseminated  ores.  Later,  when  erosion  cut  away  the  Devono- 
Carboniferous  capping,  further  concentration  took  place  by  descending  solu- 
tions, giving  rise  to  the  ore  bodies  in  crevices,  breccias,  and  synclines. 

Two  concentrations  have  occurred  in  the  Mississippian  limestones. 

Smith  (34)  agreed  with  Van  Hise  and  Bain  that  the  immediate  sources 
of  the  ores  were  the  various  limestone  formations  below  the  Pennsylvanian. 
He  assumed  that  the  surface  waters  entered  the  Mississippian  and  Cambro- 
Silurian  exposures  to  the  south  and  east.  Flowing  westward  along  these 
beds,  they  then  pass  upward  through  fractures  into  the  Mississippian  Ime- 
stones,  mingling  with  the  waters  from  these.  Both  flows  are  believed  to  have 
leached  the  smaller  quantities  of  lead  and  zinc  ores  from  the  limestones  through 
which  they  passed. 

Precipitation  of  the  ore  occurred  in  the  brecciated  portions  of  the  Boone 
formation  (Fig.  224),  and  was  caused  by  hydrocarbons  which  reduced  the 

1  Contribution  to  Geology  of  Lead  and  Zinc  Mining  Districts  of  Cherokee  Co., 
Kansas. 


646  ECONOMIC   GEOLOGY 

sulphates  to  sulphides.  These  hydrocarbons  were  set  free  by  the  dolomitiza- 
tion  of  the  limestone,  while  CO2  was  set  free  by  reaction  between  the  hydro- 
carbons and  the  dissolved  metallic  compounds.  The  CO2  thus  liberated 
attacked  some  of  the  adjacent  limestone,  a  part  of  which  became  replaced  by 
silica. 

The  repetition  of  this  cycle  gave  a  continuous  formation  of  dolomite, 
jasperoid,  and  disseminated  blende.  Secondary  concentration  of  the  ore  may 
have  occurred. 

There  are  certain  points  of  similarity  in  the  two  preceding  views. 

Quite  different,  however,  is  the  theory  worked  out  by  Buckley  and  Buehler 
(29).  According  to  them  there  was  an  elevation  of  the  region  after  the  deposi- 
tion of  the  Burlington  limestone,  followed  by  its  extensive  erosion  and  dis- 
section. As  a  result  of  this  process,  great  surface  breccias  of  residual  chert 
were  probably  produced  on  the  hillsides  and  along  the  edges  of  the  stream 
valleys.  Subsidence  during  the  Coal  Measures  period  caused  their  burial 
under  Pennsylvanian  (Middle  Carboniferous)  sediments,  where  they  now  lie 
and  have  been  identified  by  some  (Bain)  as  fault  breccias,  but  in  reality  are 
due  to  weathering. 

They  also  of  necessity  lie  along  the  horizon  of  what  is  now  a  marked 
unconformity,  giving  the  semblance  of  faults.  The  metals  and  their  ores  are 
believed  by  these  authors  to  have  been  derived  from  the  overlying  Penn- 
sylvanian rocks,  through  the  agency  of  descending  surface  waters. 

Central  Missouri  district,  containing  small  deposits  of  both  lead 
and  zinc.  In  this  area  the  ore  as  far  as  exploited  occurs  rather 
in  vertical  crevices  or  chimneys  than  in  breccias. 

The  northern  Arkansas  district,  but  partly  developed,  has  many 
rich  ores,  occurring  as  bedded  deposits  (disseminations),  veins 
(in  faults  or  filling  breccias),  or  as  replacements  (4,  5). 

Southeastern  Missouri  1  (30,  36) .  —  The  disseminated  lead  ores 
of  southeastern  Missouri  lie  mainly  within  St.  Francis,  Washington, 
and  Madison  counties,  the  geologic  section  involving  the  following 
formations :  — 


Upper  and  Middle 
Cambrian. 


Potosi  dolomite.  300  ft.  + 

Doerun  argillaceous  dolomite.  60-100  ft. 

Derby  dolomite,  thickly  bedded.  40  ft. 

Davis    formation,    chiefly    shale 
with    thin   beds    of   limestone, 


dolomite    and    limestone    con- 
glomerate. 170  ft. 

Bonneterre,  mainly  magnesian 
limestone  with  sandy  dolomite 
and  shale.  365  ft.  ± 

Lamotte  sandstone.  200  ft.  or  less. 

Unconformity. 
Pre-Cambrian.  Granite  and  rhyolite  with  intru- 

sive diabase  dikes. 

1  The  abstract  of  this  district  was  kindly  furnished  by  Dr.  E  "9...  Buckley. 


LEAD  AND   ZINC 


647 


While  the  sedimentary  series  as  a  whole  has  retained  its  originally 
approximately  horizontal  position,  there  are  numerous  local  dips, 
some  of  which  may  be  as  much  as  45°.  The  numerous  small  faults 
of  the  district  are  roughly  groupable  into  a  northeast-southwest  and 
a  northwest-southeast  system.  Most  of 
the  faults  are  of  normal  type  and  usually 
have  a  throw  of  less  than  100  feet;  but 
those  of  the  major  zones  show  aggregate 
displacements  of  700,  600,  and  400  feet 
respectively. 

The  ore  bodies  of  the  district  usually  lie 
in  pitching  troughs,  and  while  some  galena 
of  massive  crystallized  type  has  been  mined 
with  profit  from  the  Potosi,  and  upper  part 
of  the  Bonneterre,  the  disseminated  de- 
posits, which  are  the  main  source  of  the 
lead  ore  in  the  district  at  the  present  day, 
occur  mainly  in  the  lower  half  of  the  Bonne- 


LEGEND 


CHLOKITIC  LIMESTONE 


CHLOhlTIC  SHALE 


terre. 

In  the  so-called  disseminated  lead-ore 
bodies,  seven  types  of  occurrence  are  noted, 
of  which  the  first  is  the  most  important: 
(1)  disseminations  in  dolomite,  shale,  and 
chloritic  rock  ;  (2)  horizontal  sheets  along 
bedding  planes;  (3)  filling  or  lining  the 
walls  of  joints;  (4)  in  cavities,  vugs,  and 
similar  openings,  sometimes  embedded  in 
soft  blue  clay  or  mixed  with  calcite  and 
pyrite;  (5)  in  shale  along  fault  planes; 
(6)  in  cubes  and  aggregates  of  cubes  in  red 
half  foot  section  show-  d  fim  channels  and  large  openings 

ing  occurrence  of  ore  in 

limestone,  along  fault  zones  ;  (7)  as  cerussite  in  de- 
(After  composed  dolomite. 

The  disseminated  lead-ore  bodies  are  in 
part  the  result  of  the  abstraction  of  lead 
from  waters  circulating  along  channels  and  bedding  planes  in  their 
journey  from  the  surface  to  the  Lamotte  sandstone,  and  in  part 
from  solutions,  under  hydrostatic  pressure,  which  rise  along  channels 
extending  upward  into  the  dolomite,  from  the  underlying  sand- 
stone. |»f 

In  the  Bonneterre  formation  the  conditions  were  favorable  for 


FIG.   226.  —  Four  and 


Bonneterre 
Doe  Run,  Mo. 


648  ECONOMIC   GEOLOGY 

the  reduction  of  the  metallic  salts,  resulting  in  their  precipitation 
as  ore  bodies. 

The  details  of  the  deposition  are  considered  to  be  about  as  follows: 
At  the  surface  there  is  an  oxidized  zone  containing  galena,  which  is  being 
abstracted  by  surface  water  percolating  down  towards  the  Lamotte  sand- 
stone, which  on  account  of  its  high  porosity  serves  as  a  storage  reservoir 
of  water  containing  lead  in  solution.  Between  these  two  zones  is  the 
Bonneterre  formation,  with  its  carbonaceous  and  chloritic  reducing  agents, 
and  in  which  formation  the  lead  has  been  deposited. 

Channels  furnish  connecting  ways  between  the  oxidized  zone  and  the 
sandstone,  and  the  rocks  along  these  have  been  and  are  being  oxidized,  per- 
mitting the  direct  transference  of  oxidizing  solutions,  carrying  lead. 

Some  water  may  have  also  entered  the  sandstone  by  other  channels. 

The  dolomite,  which  is  now  oxidized  along  the  channels  traversing  it, 
was  at  one  time  of  a  reducing  nature,  and  the  deposition  of  the  galena 
found  in  the  rock  adjacent  to  these  passageways  must  have  occurred 
before  the  dolomite  was  oxidized.  At  such  time  any  oxidizing  solutions 
carrying  lead  which  penetrated  the  lower  horizon  of  the  Bonneterre  for- 
mation must  have  been  brought  in  from  other  areas,  chiefly  through  the 
rock  outcropping  near  the  area  of  igneous  rocks.  The  galena  in  the 
crevices  may  have  been  introduced  in  part  by  ground  water  from  the  sur- 
face, and  in  part  from  water  rising  from  the  Lamotte  sandstone.  It  is 
thought  that  the  ore  bodies  in  the  Bonneterre  are  mainly  subsequent  to 
the  establishment  of  zones  of  communication  along  the  oxidized  channels. 
The  original  source  of  the  lead  was  the  igneous  rocks,  its  transference  to 
the  sedimentary  formation  having  taken  place  during  successive  periods 
of  decomposition  by  the  surface  and  ground  water  circulations,  the  waters 
carrying  the  metallic  compounds  down  into  the  sea  where  they  became 
incorporated  in  the  sediments  then  forming. 

Upper  Mississippi  Valley.  —  This  area  embraces  southwestern 
Wisconsin  (63),  eastern  Iowa  (20,  21),  and  northwestern  Illinois 
(ll),  but  the  first-named  state  contains  the  most  productive  terri- 
tory. The  section  in  the  Wisconsin  area  (63) ,  which  may  be  taken  as 
typical,  involves  the  following  formations,  beginning  at  the  top :  — 

FEET 

Pleistocene                            Loess,  alluvium,  and  soil  7 

Silurian                                  Niagara  limestone  50 

IMaquoketa  shale  160 

Galena  limestone  230 

Platteville  limestone  (Trenton)  55 

St.  Peter  sandstone  70 

Lower  Magnesian  limestone  200 

Cambrian                               Potsdam  sandstone  700 
Pre-Cambrian                       Crystalline  rocks 

A  bituminous  shaly  layer,  known  as  the  oil  rock,  occurs  at  the  base 
of  the  Galena,  and  below  it,  or  at  the  top  of  the  Platteville,  is  a  fine- 
grained limestone  called  the  glass  rock.  While  the  series  as  a  whole 
shows  a  very  gentle  southwest  dip,  there  are  a  few  low  folds. 


LEAD  AND   ZINC 


649 


The  ores  occur  in  crevices  (Fig.  227)  in  the  dolomite  or  as  dis- 
seminations in  certain  beds.  In  the  former  the  order  of  deposition 
or  arrangement  is  (1)  marcasite,  (2)  sphalerite  with  some  galena, 
and  (3)  galena. 

The  crevice  deposits  (Fig.  227)  form  the  most  important  source 
of  the  ore,  and  consist  commonly  of  a  vertical  fissure,  which  at  its 
lower  end  splits  into  two  horizontal  branches  called  flats,  while  these 
in  turn  pass  into  steeply  dipping  fissures  termed  pitches.  Galena 
commonly  predominates  in  the  crevices,  while  sphalerite  occurs 


j TRENTON 
3  LIMESTONE 


:J  GLASS  ROCK 


J GALENA 
J  LIMESTONE 


FIG.  227.  —  Section  showing  occurrence  of  lead  and  zinc  ore  in  Wisconsin  ;   fissure 
ore  in  flats  and  pitches,  and  disseminated  ore  in  wall  rock.     (After  Chamberlin.) 

in  great  abundance  lower  down.  The  main  crevices  extend  approxi- 
mately east  and  west,  but  there  are  other  less  important  intersect- 
ing fissures. 

The  chief  ore  bodies  lie  in  the  lower  part  of  the  Galena  limestone. 
Flats  unconnected  with  pitches  are  found  just  above  the  oil  rock  at 
base  of  Galena,  and  in  the  lower  part  of  the  glass  rock,  while  dis- 
seminated deposits  may  occur  in  the  same  position  as  these  flats,  or 
even  in  the  oil  rock. 

The  ores  below  the  ground-water  level  are  galena,  sphalerite,  and 
iron  sulphide  (usually  marcasite),  while  above  this  they  are  galena, 
smithsonite,  and  limonite.  Calcite  is  a  common  gangue  mineral. 

In  explaining  the  origin  of  the  ore  bodies  some  have  claimed  (63) 
that  the  metallic  minerals  were  gathered  by  circulating  meteoric 
waters  from  the  Galena  limestone;  these  waters  entered  the  lime- 
stone probably  from  the  northeast,  where  the  overlying  shales  had 
been  eroded,  and  moved  to  the  southwest.  The  ore  was  precipi- 


650 


ECONOMIC   GEOLOGY 


tated  in  crevices  as  sulphides,  either  because  of  a  reducing  action 

exerted  by  bituminous  matter  present  in  the  rocks  or  by  hydrogen 

sulphide. 

Surface  waters  descending  crevices  have  produced  a  secondary 

concentration,  which  has  resulted  in  a  separation  of  the  zinc  and 

galena,  accompanied  by  a 
transferal  of  much  of  the 
former  to  lower  levels. 

More  recently  Cox  (18) 
has  expressed  the  opinion 
that  the  Maquoketa  shale 
was  the  probable  source  of 
the  lead  and  zinc. 

Lead  was  discovered  in  the 
Upper  Mississippi  area  as  early  as 
1692,  and  the  first  mining  was 
done  in  Dubuque  in  1788.  The 
early  work  was  restricted  to  lead 
mining  entirely,  the  zinc  ores  be- 
ing disregarded.  The  increased 
price  of  zinc  in  later  years  led  to 
the  opening  of  deposits  below 
water  level,  and  a  continued 
production  of  zinc.  Mechanical 
concentration  methods  have  been 
introduced,  and  while  the  galena 
can  be  separated  quite  thoroughly 
from  the  sphalerite  and  marca- 
site,  the  last  two  are  parted  with 
difficulty.  On  account  of  the 
presence  of  marcasite  in  most  of 
the  mines,  the  zinc  ores  of  this 
district  command  a  lower  price 
than  those  from  other  areas. 

Both  electrostatic  and  electro- 
magnetic separation  have  been  used  on  these  ores  with  good  results.  Thus 
working  on  a  material  that  assays  30  per  cent  zinc  and  20  per  cent  iron,  the 
zinc  product  assays  56  per  cent  zinc  and  4  per  cent  iron,  while  the  iron  prod- 
uct gave  39  per  cent  iron  and  5  per  cent  zinc. 

The  crude  ore  yields  from  5  to  over  20  per  cent  concentrates,  and  these  in 
1914  averaged  35.05  per  cent  zinc. 

Foreign  Deposits.1 — Europe  contains  two  important  lead-zinc  districts, 
somewhat  analogous  to  the  Mississippi  Valley  type.  The  first  of  these  is  the 
Moresnet  district  in  Belgium  and  Prussia,  where  the  ores,  which  carry  spha- 
lerite, galena,  iron  sulphide  and  calcite  are  associated  with  faults  in  the  Devon- 
ian and  Carboniferous  limestones,  and  have  been  deposited  in  cavities  or  by 
1  Vogt,  Krusch  und  Beyschlag,  Lagerstatten. 


SCALE    OF    FEET 


E3 

01U  Diggings 


Underground 
Workings 


Structural 
Contours 


FIG.  228.  — Map  of  a  portion  of  Wisconsin 
lead  and  zinc  district,  showing  strike  of 
crevices,  underground  contours  of  Galena 
limestone,  and  underground  workings. 
(After  Bain,  U.  S.  Geol.  Surv.,  Bull.  294.) 


LEAD  AND   ZINC  651 

replacement.     Considerable  oxidized  ore  was  obtained  from  the  upper  part 
of  the  ore  bodies. 

The  second  of  these,  located  in  Silesia,  Prussia,  is  among  the  world's  leading 
producers.  The  ore  here  appears  to  form  replacements  in  dolomitized  Tri- 
assic  limestone  at  two  horizons,  the  lower  one  yielding  sphalerite,  galena  and 
marcasite,  and  the  upper  one  smithsonite. 

Other  European  occurrences  in  limestone  are  those  of  Raible  and  Bleiberg 
in  Austria;  Santander,  Spain,  Sardinia),  etc. 

Uses  of  Lead  and  Zinc.  —  Both  of  these  are  important  base  metals; 
although  in  value  of  production  they  rank  below  gold,  silver,  copper, 
and  iron,  neither  do  they  come  into  competition  with  these,  for 
they  lack  the  high  tenacity  of  iron  and  steel,  the  conductivity  of 
copper,  and  the  value  resulting  from  scarcity  possessed  by  gold  and 
silver.  They  are  of  value,  however,  on  account  of  their  high  mallea- 
bility and  the  application  of  their  compounds  for  pigments. 

Uses  of  Lead.  —  Lead  finds  numerous  uses  in  the  arts,  the  most 
important  being  for  white  lead.  Litharge,  the  oxide  of  lead,  is  used 
not  only  for  paint,  but  also  somewhat  in  the  manufacture  of  glass, 
although  red  lead  is  more  frequently  employed  instead. 

A  further  use  of  lead  is  for  making  pipe  for  water  supply,  sheet 
lead  for  acid  chambers,  and  shot. 

Among  the  alloys  formed  by  lead  are  type  metal  (lead, 
antimony,  and  bismuth,  with  copper,  or  iron),  white  metal, 
organ-pipe  composition,  and  fusible  alloys  used  in  electric 
lighting. 

In  addition  to  these,  the  acetate,  carbonate,  and  other  com- 
pounds are  used  in  medicine.  In  smelting,  lead  is  used  to  col- 
lect the  gold  and  silver,  and  the  bulk  of  the  lead  of  commerce 
is  obtained  as  a  by-product  in  the  smelting  of  the  precious 
metals. 

Uses  of  Zinc.  —  Metallic  zinc  is  used  for  a  variety  of  purposes, 
partly  owing  to  its  slight  alteration  in  air,  and  secondly,  because 
it  can  be  rolled  into  thin  sheets.  In  this  condition  it  is  used 
extensively  for  roofing  and  also  for  plumbing,  and  as  a  coating 
to  iron  this  metal  is  extensively  called  for  in  galvanizing.  It 
is  also  used  for  cyaniding  gold. 

One  of  the  most  important  applications  is  for  making  brass,  which 
is  ordinarily  composed  of  from  66  to  83  parts  of  copper  and  27  to 
34  parts  of  zinc.  The  composition  varies,  entirely  depending  on  the 
use  to  which  it  is  to  be  put,  and,  with  the  variation  in  proportion, 
the  color  becomes  more  golden,  or  whiter,  according  as  the  percent- 
age of  copper  is  increased  or  decreased.  With  an  increase  in  the 


652 


ECONOMIC   GEOLOGY 


amount  of  zinc,  the  alloy  becomes  more  fusible,  harder,  and  more 
brittle. 

White  metal  is  an  alloy  of  zinc  and  copper  in  which  zinc  pre- 
dominates, and  which  is  often  employed  for  making  buttons. 
Imitation  gold  is  also  made  by  alloying  zinc  with  a  predominance 
of  copper,  varying  from  77  to  85  per  cent  of  the  mass,  and  this  is 
in  common  use  as  "  gold  foil  "  for  gilding.  Zinc  is  also  made  use  of 
in  the  construction  of  electric  batteries. 

German  silver  has  60  parts  copper,  20  zinc,  and  20  nickel.  Its 
use  is  for  mathematical  and  scientific  instruments. 

Zinc  is  used  wholly  or  in  part  as  the  base  of  four  pigments,  viz. 
zinc  oxide,  leaded  zinc  oxide,  zinc-lead  oxide,  and  lithophone.  All 
of  these  can  be  made  directly  from  the  ore,  and  the  first  three  usually 
are.  Zinc  oxide  is  the  most  important  of  the  four.  Lithophone  is 
an  intimate  mixture  by  chemical  precipitation  of  zinc  sulphide  and 
barium  sulphate. 

Production  of  Lead  and  Zinc.  —  The  production  of  refined  lead 
and  spelter  in  the  United  States  from  1875  to  1914  are  given 
below.  Other  statistics  of  production  are  given  in  the  tables  on 
pages  653  to  655. 

The  imports  of  manufactured,  block,  and  pig  zinc  amounted  to 
$1,363,884  worth  in  1912;  $632,036  in  1913,  and  $84,120  in  1914, 
The  total  amount  of  zinc  ore  imported  in  the  year  1914  was 
valued  at  $149,503.  The  total  value  of  the  exports  of  ore  and 
manufactured  zinc  in  1914  were  valued  at  $9,381,050.  The  im- 
ports of  zinc  oxide  in  1914  amounted  to  2,629  short  tons,  while 
the  exports  in  that  same  year  amounted  to  15,592  short  tons, 
valued  at  $1,408,525. 

The  total  value  of  lead  imported  in  1914  was  $504,978,  while 
the  exports  were  valued  at  $4,501,674  for  the  same  period. 


PRODUCTION  OF  REFINED  LEAD  AND  SPELTER  IN  THE  UNITED  STATES, 
1875  TO  1914,  IN  SHORT  TONS 


YEAR 

REFINED  LEAD 

SPELTER 

1875 

$6  913  620 

15  823 

1880  

9,572,500 

23  239 

1885    .  .     .... 

10  095  360 

40  688 

1890  

14,205,960 

63,683 

1895    .    .... 

15  092  608 

89  686 

1900  

32,364,024 

123,886 

1905    

36  500  858 

203  849 

1910  

41,383,936 

269,184 

1914  .  .    

42  285,516 

353  049 

LEAD  AND  ZINC 


653 


PRODUCTION  OF  PRIMARY  SPELTER  IN  THE  UNITED  STATES  IN  1912-1914, 
APPORTIONED  ACCORDING  TO  SOURCE  OF  ORE,  IN  SHORT  TONS 


SOURCE 

QUANTITY 

1912 

1913 

1914 

Arizona       
Arkansas    

4,092 
604 
1,672 
60,841 
6,800 
3,952 
5,668 
394 
149,557 
14,196 
6,132 
16,941 
6,882 

4,675 
478 
1,012 
58,113 
10,190 
1,345 
9,956 
172 
129,018 
35,604 
5,828 
24,247 
3,765 
152 
6,397 
2,635 
303 
9,503 
116 
33,743 

3,905 
670 
159 
41,746 
22,720 
1,833 
10,634 
147 
114,019 
55,986 
6,041 
27,734 
4,345 

9,449 
6,122 
156 
6,818 
20 
30,914 

Idaho          .           

Kansas        

Missouri     

Montana    
Nevada       
New  Jersey     

Oklahoma             

2,041 
1,935 
245 
7,756 
62 
34,137 

Tennessee        
Texas     
Utah 

Virginia      
Wisconsin        

Total  from  domestic  ores    .     . 

Foreign 
Canada        

323,907 

337,252 

343,418 

4,199 
10,700 

1,424 
6,205 
1,175 
620 

4,538 
5,093 

Europe   
Siberia    



14,899 

9,424 

9,631 

Grand  Total     

338,806 

346,676 

353,049 

PRODUCTION  OF  SPELTER  IN  THE   UNITED  STATES,  1910-1914,  APPORTIONED 
ACCORDING  TO  THE  LOCALITY  IN  WHICH  SMELTED,  IN  SHORT  TONS 


1910 

1911 

1912 

1913 

1914 

Illinois      

73  038 

83  130 

88  397 

106  654 

127  946 

Kansas 

105  697 

98  413 

101  104 

74  106 

44  510 

Missouri        
Oklahoma 

5,571 
34  760 

4,116 
46  315 

7,805 
76  925 

5,085 
83  214 

3,550 
91  367 

Eastern  and  Southern     . 
Colorado       . 

43,606 
6  512 

47,155 

7  397 

56,'  252 
9  043 

69,063 
8  554 

77,593 
8083 

Total     

269,184 

286,526 

338,806 

346,676 

353,049 

PRODUCTION  OF  ZINC  IN  CANADA,  1912 — 1914 


YEAR 

ZINC  ORE  SHIPPED 

METALLIC  ZINC  IN 
ORE  SHIPPED 

Tons 

Spot  Value 

Pounds 

Final  Value 

1912     . 

6,415 
7,889 
10,893 

$215,149 
186,827 
262,563 

5,354,700 
7.069,800 
9,101,460 

$371,777 
399,302 
474,459 

1913     . 

1914     

654 


ECONOMIC   GEOLOGY 


The  Canadian  imports  of  zinc  blocks,  pigs,  and  sheets  in  1914 
were  valued  at  $189,785,  and  spelter  at  $551,031. 

SOURCES  OF  PRIMARY  LEAD  SMELTED  OR  REFINED  IN  THE  UNITED  STATES, 
1912-1914,  IN  SHORT  TONS 


SOURCE  OF  ORE 

1912 

1913 

1914 

Domestic  ore: 
Alaska 

45 

6 

Arizona      

3,891 

4,901 

5,602 

52 

California       
Colorado   

811 
37,039 

3,294 
42,840 

3,698 
41,198 

Idaho    
Illinois        .           
Iowa      .                 
Kansas       .           

127,780 
513 

1,937 

137,802 
619 

1,504 

177,827 
427 
34 
1,043 

Kentucky             
Missouri    .           
Montana  .           
Nevada      .           
New  Mexico 

91 
162,610 
2,517 
5,699 
2  511 

16 
152,430 
3,256 
6,142 
1,821 

16 
194,275 
4,386 
5,996 
741 

North  Carolina        .... 
Oklahoma 

34 
2,500 

10 

3,214 

3,916 

Oregon       

21 

37 

17 

South  Dakota     
Texas    
Utah     
Virginia      
Washington   ...... 
Wisconsin       ....... 

12 
30 
60,664 
85 
53 
3,301 

7 
108 
71,069 
878 
9 
2,639 

2 

89 
88,976 
143 
2 

1,818 

Undistributed     
Zinc  residues       .      .      .     ;".'.'•    ' 

120 
3,131 

63 
3,765 

99 
4,125 

Total  from  domestic  ores  . 
Foreign  ore: 
Africa    
Canada      
Mexico       
South  America    .      .      . 
Other  foreign        .      .     .  '    . 
Foreign  base  bullion: 
Mexico       

415,395 

1,774 
29 
7,407 
2,332 
30 

76,805 

436,430 

5,976 
16 
4,512 
2,617 
102 

37,359 

534,482 

2,942 
2 
2,386 
1,821 
488 

21,689 

Total  from   foreign   ore  and 
base  bullion      .... 

88.377 

50,582 

29,328 

Grand  total  derived  from  all 
sources    

503,772 

487,012 

563,810 

PRODUCTION  OF  LEAD  IN  CANADA,  1912-1914 


YEAR 

1  POUNDS 

VALUE 

LEAD  ORES 
SHIPPED, 
TONS 

1  LEAD 
CONTENTS, 
POUNDS 

SILVER 
CONTENTS, 
OUNCES 

1912    
1913 

35,763,476 
37  662  703 

$1,597,554 
1  754,705 

59,814 
85,978 

45,896,537 
53,807,570 

2,366,294 
2,564,155 

1914    

36,337,765 

1,627,568 

70,207 

50,537,130 

2,501,820 

Difference  between  production  of  lead,  and    that  in  ore  shipped  due  in  part  to  ore 
accumulations  at  smelters. 

The  Canadian  imports  of  lead  in  all  shapes  in  1914  were  valued 
at  $928,532,  while  the  exports  of  pig  and  lead  in  ores  and  concen- 
trates had  a  total  value  of  $22,188. 


LEAD  AND   ZINC 


655 


THE  WORLD'S  PRODUCTION  OF  SPELTER,  1912-1913,  IN  SHORT  TONS 


1912 

1913 

Australia      .      .      

2,531 
21  609 

4,105 
23  928 

220,678 

217  928 

France  and  Spain      .     

79,543 
298  794 

78,289 
312  075 

63,086 

65  197 

Holland 

26  380 

26  811 

8  959 

10  237 

Poland                                                       .                 ... 

9  659 

8  389 

United  States 

338  806 

346  676 

Total    /......     .     . 

1,070,045 

1,093,635 

United  States  percentage  of  world's  production      . 

31.7 

31.7 

THE  WORLD'S  PRODUCTION  OF  LEAD,  1912-1913,  IN  SHORT  TONS 


Country 

1912 

1913 

118  387 

127  867 

Austria-Hungary       

23,589 
56  438 

26,565 
55  997 

Canada         

17,968 

18  849 

34  282 

30  864 

194  666 

199  627 

32  187 

33  620 

15  983 

20  282 

Italy                                     

23  699 

23  920 

4  960 

3  968 

Mexico                      

132  276 

68  343 

1  102 

1  102 

Spain       

205,799 

223  767 

1  433 

1  653 

Turkey  in  Asia     
Other  countries           

13,779 

13,448 
392  517 

15,322 
6,834 
411  878 

Total  

1,282,513 

1.970  458 

United  States  percentage  of  world's  production     . 

30.6 

32.4 

REFERENCES   ON  LEAD    AND    ZINC 

These  references  refer  to  deposits  which  are  predominatingly  or  exclusively 
lead  and  zinc,  others  are  under  Silver-Lead  and  Gold-Silver. 

GENERAL.  1.  Allen  and  Crenshaw,  Amer.  Jour.  Sci.,  XXXIV:  341,  1912. 
(Genetic  conditions  of  zinc,  cadmium,  mercury.)  2.  Ingalls,  Lead  and 
Zinc  in  the  United  States.  New  York,  1908.  (Historic.)  3.  Wang, 
Amer.  Inst.  Min.  Engrs.,  Bull.,  Sept.,  1915.  (Weathering.)  Arkansas: 
4.  Adams,  U.  S.  Geol.  Surv.,  Prof.  Pap.  24,  1904.  5.  Branner,  Amer. 
Inst.  Min.  Engrs.,  Trans.,  XXXI:  572,  1902.  Also  Ark.  Geol.  Surv., 
V,  1900.  Colorado:  6.  Argall,  G.  O.,  Eng.  and  Min.  Jour.,  LXXXIX: 
261,  1910.  (Recent  developments  at  Leadville.)  7.  Argall,  G.  O.,  Eng. 
and  Min.  Jour.,  Aug.  26,  1911.  (Ox'd  ores  Leadville.)  8.  Argall,  P., 
Min.  and  Sci.  Press,  July  11  and*  25,  1914.  (Siderite  and  sulphides, 
Leadville.)  9.  Butler,  G.  M.,  Econ.  Geol.,  VIII:  1,  1913.  (New 
developments,  Leadville)  and  Ibid.,  VII:  315,  1912.  10.  Emmons, 
U.  S.  Geol.  Surv.,  Mon.  XII,  1886.  (Leadville.)  10a.  Emmons  and 


356  ECONOMIC  GEOLOGY 

Larsen,  Ibid.,  Bull.  530:  42,  1913.  (Creede.)  11.  Emmons  and  Irving, 
Ibid.,  Bull.  320,  1907.  (Downtown  district,  Leadville.)  lla.  Irving 
and  Bancroft,  U.  S.  Geol.  Surv.,  Bull.  478,  1911.  (Lake  City.)  12. 
Moore,  Econ.  Geol.,  VII:  590,  1912.  (Recent  developments,  Leadville.) 

13.  Ransome,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  II:  229,  1901.     (Rico 
Mts.)     Idaho:    14.  Lindgren,  U.  S.  Geol.  Surv.,  20th  Ann.  Rept.,  Ill: 
190,   1900.     (Wood  River  district.)     15.  Schrader,  U.  S.  Geol.  Surv., 
20th  Ann.  Rept.,  Pt.  Ill:    187.     Illinois:    16.  Bain,  U.  S.  Geol.  Surv., 
Bull.  246,  1906.     (N.  W.  111.)     17.  Bain,  Ibid.,  Bull.  225:    202,  1904. 
(111.)     18.  Cox,  111.  Geol.  Surv.,  Bull.  21,  1914.     (N.  W.  111.)  and  Bull. 
16:   24,  1911.     19.  Cox,  Econ.  Geol.,  VI:   427  and  582,  1911.     (Origin 
Up.  Miss.  Val.  ores.)     Iowa:  20.  Bain,  U.  S.  Geol.  Surv.,  Bull.  294,  1906. 
21.  Calvin  and  Bain,  la.  Geol.  Surv.,  X:   370,  1900.     22.  Leonard,  la. 
Geol.  Surv.,  VI:    10,   1897.     Kansas:    23.  Haworth  and  others,  Kas. 
Geol.  Surv.,  VIII,  1904.     Kentucky:   24.  Miller,  Ky.  Geol.  Surv.,  Bull. 
2,  1905.     (Cent.  Ky.)     25.  Ulrich  and  Smith,  W.  S.  T.,  U.  S.  Geol. 
Surv.,    Prof.    Pap.    36,    1905.     Massachusetts:     26.  Clapp    and    Ball, 
Econ.   Geol.,   IV:    239,    1909.     (Newburyport.)     Missouri:    27.  Bain, 
Van  Hise  and  Adams,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  II:   23,  1901. 
28.  Ball  and  Smith,  Mo.  Bur.  Geol.  Min.,  2d  ser.,  I,  1903.     (Central 
Mo.)     29.  Buckley  and  Buehler,  Mo.  Bur.  Geol.  Min.,  2d  ser.,  IV,  1905. 
(Granby  area.)     30.  Buckley,  Mo.  Bur.  Geol.  Min.,  IX,  1908.     (S.  E. 
Mo.)     31.  Jenney,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXII:    171,  1894. 
(Genesis.)     32.  Siebenthal,  Econ.  Geol.,  I:    119,  1906.     (Joplin.)     33. 
Siebenthal,  U.  S.  Geol.  Surv.,  Bull.    606,  1916.     (Origin  Joplin  ores.) 
34.  Smith  and  Siebenthal,  U.  S.  Geol.  Atlas  Folio,  No.  148,  1907.     (Jop- 
lin.)    35.  Wheeler,  Eng.  and  Min.  Jour.,  LXXVII:  517,1904.     (RePn 
lead  to   igneous   rock.)     36.  Winslow,  Mo.  Geol.  Surv.,  VI   and  VII, 
1894.     (Mo.  and  general.)     Montana:  37.  Pepperberg,  U.  S.  Geol.  Surv. 
Bull.  430:    135,   1910.     (Bearpaw  Mtns.)     Nevada:    38.  Bain,   U.   S. 
Geol.  Surv.,  Bull.  285.     (Zinc.)     New  Jersey:   39.  Kemp,  N.  Y.  Acad. 
Sci.,  Trans.  XIII:  76,  1894.     40.  Spencer,  N.  J.  Geol.  Surv.,  Ann.  Rept.. 
1908:,  23,  1909.     41.  Wolff,  U.  S.  Geol.  Surv.,  Bull.  213:    214,  1903, 
New  Mexico:    42.  Lindgren,  Graton  and  Gordon,  U.  S.  Geol.  Surv.. 
Prof.  Pap.  68,  1910.     (General.)     43.  Lindgren.  Ibid.,  Bull.  380,  1908, 
(Tres  Hermanas  district.)     New  York:    44.  Ihlseng,  Eng.   and  Min. 
Jour.,    LXXXV:    630,  1903.     (Ellenville.)     45.  Newland,  N.  Y.  State 
Museum,  Bull.  161:    101,  1912.     (St.  Lawrence  County.)     Oklahoma: 
46.  Siebenthal,  U.  S.  Geol.  Surv.,  Bull.  340,  1907.     47.  Snider,  Okla. 
Geol.  Surv.,  Bull.  9,  1912.     Pennsylvania:   48.  Clerc,  U.  S.  Geol.  Surv., 
Min.  Res.,  1882:  61.     49.  Hall,  Sec.  Pa.  Geol.  Surv.,  D3:  239.    Tennes- 
see:  50,  Keith,  U.  S.  Geol.  Surv.,  Bull.  225:   208,  1904.     51.  Osgood, 
Tenn.  Geol.  Surv.,  Bull.  2,  1910.     52.  Purdue,  Tenn.  Geol.  Surv.,  Bull. 

14,  1912.     (N.  E.  Tenn.)     53.  Watson,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXXVI:    681,  1906.     United  States:    54.  Ingalls,  Lead    and  Zinc  in 
the   United   States.     New  York,    1908.     (Historic.)     55.  U.   S.    Geol. 
Surv.,    Mineral  Resources,   published   annually.     Statistics   and   trade 
data.     Utah:  56.  Crane,  Amer.  Inst.  Min.  Engrs.,  Bull.  106:  2147,  1915. 
(Tintic.)     57.  Tower  and  Smith,  U.  S.  Geol.  Surv.,  19th  Ann.  Rept.,  Ill: 


LEAD  AND  ZINC  657 

601, 1899.  (Tintic.  District  as  a  whole  treated  under  Lead-Silver  ores.) 
58.  Zalinski,  Eng.  and  Min.  Jour.,  June  21, 1913.  (Tintic  ox'd  zinc  ores.) 
Virginia:  59.  Watson,  Va.  Geol.  Surv.,  Bull.  1,  1905;  also  Min.  Res. 
Va.,  1907.  60.  Watson,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXXVII: 
304,  1907.  (Metallurgy,  etc.)  Washington:  61.  Bancroft,  U.  S.  Geol. 
Surv.,  Bull.  470,  1910.  (Metaline  district.)  Wisconsin:  62.  Chamber- 
lin,  Geol.  of  Wis.,  Ft.  IV,  1882.  63.  Grant,  Wis.  Geol.  and  Nat.  Hist. 
Surv.,  Bull.  14,  1906.  64.  Wright,  C.  A.,  Bur.  Mines,  Tech.  Pap.  95. 
(Mining  and  milling.)  Canada:  See  references  under  Silver-Lead  ores. 


CHAPTER   XVIII 
SILVER-LEAD   ORES 

THE  silver-lead  ores  form  a  large  class,  of  rather  wide  dis- 
tribution, and  while  the  two  metals  characterizing  the  group  are 
prominent,  there  may  also  be,  and  often  is,  present  a  variable 
quantity  of  other  metals  such  as  gold,  zinc,  and  copper.  Indeed, 
some  that  are  included  in  this  chapter  might  possibly  be  placed 
in  the  following  one.  The  silver  contents,  though  sometimes 
high,  are  not  necessarily  visible,  and  may  be  contained  within 
the  galena  as  Ag2S.1 

The  ore  bodies  as  a  whole  present  a  variety  of  forms,  the 
ore  having  been  deposited  either  by  cavity  rilling  or  replace- 
ment, or  both.  Most  of  the  important  occurrences  seem  to 
have  been  formed  at  intermediate  depths.  Oxidation  zones 
frequently  cap  the  ore  body,  and  downward  secondary  enrich- 
ment has  probably  occurred  in  some  cases. 

Silver-lead  ores  form  a  widely  distributed  class  in  the  Cor- 
dilleran  region  of  the  United  States  and  supply  most  of  the 
lead  mined  in  this  country.  Deposits  are  prominent  in  Colo- 
rado, Idaho,  and  Utah,  but  are  also  known  in  New  Mexico, 
Montana,  Wyoming,  Nevada,  Arizona,  California,  and  South 
Dakota. 

Canada  supplies  a  small  but  steady  production  from  British 
Columbia,  while  in  other  foreign  countries  districts  worth 
noting  for  either  commercial  or  historic  importance  are  Broken 
Hill,  New  South  Wales;  Clausthal  and  Freiberg,  Germany; 
Przibram,  Bohemia;  Sala,  Sweden;  Laurium,  Greece;  Mexico, 
etc. 

Deep-vein  Zone  Deposits 

United  States.  —  Silver-lead  mines  of  this  class  are  unim- 
portant in  the  United  States,  but  some  carrying  tourmaline 
occur  in  the  Boulder  batholith  (15)  of  Montana  (p.  593). 

1  Nissen,  A.  E.,  and  Hoyt,  S.  L.,  Econ.  Geol.,  X:   172,  1915. 
658 


SILVER-LEAD  ORES  659 

Canada.  —  In  Canada  there  are  certainly  two  occurrences 
in  British  Columbia  that  should  be  mentioned.  One  of  these, 
the  Sullivan  mine  (30),  northwest  of  Cranbrook,  represents 
a  conformable  replacement  of  argillaceous  quartzites  by  galena, 
blende,  iron  sulphides,  and  jamesonite  (Pb2Sb2,$5),  with  garnet, 
diopside,  actinolite,  and  biotite.  This  has  been  a  good  pro- 
ducer. 

The  other  deposit,  no  longer  worked,  is  the  St.  Eugene 
at  Moyie  (29),  which  is  a  replacement  in  a  fractured  quartzite, 
and  shows  somewhat  similar  mineral  composition  to  the  pre- 
ceding. 

Other  foreign  deposits.  —  The  best-known  example  perhaps  of  this 
group  is  the  Broken  Hill  Lode  in  western  New  South  Wales.1 

This  great  lode,  discovered  in  1883,  was  first  worked  for  silver,  then 
silver  lead,  and  in  recent  years,  also  zinc.  The  rocks  of  the  region  include: 
(1)  pre-Cambrian  sediments,  chiefly  arkoses  and  sandstones  near  the  lode, 
all  altered  to  gneisses  and  schists;  (2)  amphibolites  derived  from  eruptives; 
and  (3)  granite  gneisses  and  pegmatites.  Regional  metamorphism  was 
accompanied  by  shearing  along  the  line  of  the  lode,  and  later  injection  of 
pegmatite  along  the  ore  zone.  There  was  also  developed  in  the  country 
rock,  garnet,  gahnite  (ZnAl2O4),  sillimanite,  and  rhodonite. 

The  ore  bodies,  which  are  associated  with  the  shear  zone,  often  form 
peculiar  saddle-shaped  masses.  A  gossan  rich  in  manganese  and  iron, 
passes  downwards  into  oxidized  ores  of  lead,  silver,  and  some  copper,  while 
below  this  is  a  coarse-grained  mixture  of  sphalerite  and  galena,  carrying 
silver,  and  intergrown  with  quartz,  garnet,  feldspar,  and  rhodonite.  Oxi- 
dation extends  to  depths  of  500  to  600  feet,  and  secondary  enrichment  is 
well  marked.  The  primary  ores  average  3  to  14  oz.  silver,  14  to  16  per 
cent  lead,  and  8  to  18  per  cent  zinc. 

The  theories  advanced  to  explain  these  saddle  deposits  include,  lateral 
secretion  (Pittman  and  Jacquet);  bedded  deposits  (Krusch,  Stelzner  and 
Bergeat);  epigenetic  origin  (Beck),  and  contact  metamorphism  (Vogt). 
Moore  2  suggests  replacement  in  the  hanging  wall  of  the  tabular  shear  zone, 
the  beds  being  replaced  in  such  a  way  as  to  give  the  saddle  form. 

In  this  same  group  may  also  be  mentioned  the  lead-silver-zinc  ores  of 
Sala,  Sweden,  which  occur  in  dolomitized  limestone.  One  series  of  steeply- 
dipping  ore  bodies  carries  silver  and  lead,  with  some  blende,  pyrite,  arseno- 
pyrite,  and  stibnite;  the  other  series  of  lesser  dip  predominates  in  zinc. 
The  ore  minerals  are  intergrown  with  salite,  tremolite,  actinolite,  epidote, 
biotite,  and  a  little  tourmaline.  They  are  regarded  as  replacements,  but 
show  no  direct  connection  with  any  instrusive.3 

1Vogt,  Krusch,  and  Beyschlag,  Ore  Deposits,  Translation,  I:  399,  1914. 
Jacquet,  Mem.  Geol.  Surv.,  N.  S.  W.,  No.  5  Geology,  1894;  Mawson,  Mem. 
Roy.  Soc.  S.  Austral.,  1912;  Austral.  Inst.  Min.  Engrs.,  VI,  No.  2,  17,  1910. 

2  Manuscript  notes,  kindly  loaned  to  author 

3  Vogt,   Krusch,  and  Beyschlag,   Lagerstatten,  II:    264,   1912;  also  Sjogreni 
Internat.  Geol.  Cong.,  Stockholm,  1910,  Guidebook,  No.  28. 


660 


ECONOMIC  GEOLOGY 


Deposits  Formed  at  Intermediate  Depths 

United  States.  —  Most  of  the  occurrences  of  silver-lead  ores 
found  in  the  United  States  are  placed  in  this  group. 

Cceur  d'Alene,  Idaho  (13).  —  The  Coeur  d'Alene  district 
(which  is  really  made  up  of  several  local  mining  districts) 


120"      110"      118"      117"       110"      115"      114       113J      112"      111"      110- 


120°      119°       118°       117"       110"       115°       114°       113°       112°       111 


FIG.  229.  —  Map  showing  location  of  Coeur  d'Alene,  Ido.,  district.     (After  Ran- 
some,  U.  S.  Geol.  Surv.,  Prof.  Pap.  62.) 

lies  in  Shoshone  County,  mostly  on  the  western  slope  of  the 
Cceur  d'Alene  Mountains.  Wallace  is  the  principal  town, 
but  there  are  several  smaller  ones,  as  Wardner,  Mullan,  Burke, 
Mace,  Gem,  and  Murray. 

The  prevailing  rocks  here  are  a  thick  (10,000  feet),  apparently 
conformable  series  of  shales,  sandstones,  and  some  limestones  of 
Algonkian  age,  which  on  the  west  are  faulted  down  against  granitic 
and  gneissic  rocks,  but  extend  some  distance  to  the  eastward. 

The  condensed  section  is  as  follows:  — 

FEET 

.      .      .  1,000  + 

.      .      .  4,000 

.      .      .  1,000  + 

.     .     .  1,200 

.     .     .  2,000 

8,000 


Striped  Peak  shales  and  sandstones  .  .  . 
Wallace  sandstones,  shales  and  limestones 
St.  Regis  shales,  and  sandstones  .  .  .  . 

Revett  white  quartzite 

Burke  shales  and  sandstones 

Prichard  shales  and  sandstones     .     .     .     . 


17,200  + 


PLATE  LXI 


FIG.    1.  —  View   near   Linden  in   Wisconsin  lead  and   zinc   district.       (H.    Ries, 

photo.) 


FIG.  2.  —  View  looking  north  over  the  Coeur  d'Alene  Mountains  from  the  Stem- 
winder  tunnel  above  Wardner.  Shows  mature  dissection  of  plateau-like  uplift. 
Town  of  Wardner  in  foreground.  (After  Ransome,  U.S.  GeoL  Surv.,  Prof.  Pap. 
62.) 

(661) 


662 


ECONOMIC   GEOLOGY 


The  igneous  rocks  includes  some  small  intrusive  stocks  of  mon- 
zonite,  and  a  few  dikes  of  diabase  and  lamprophyre-like  rocks, 
but  the  age  of  all  is  uncertain. 


Areas  in  which  Areas  in  which  occur       Areas  in  which 

occur  lead-silver  lead-silver  deposits  of        occur  copper 

deposits  of  secondary  Importance  deposits 

known  primary  Bo  far  at  present 

importance  known 


FIG.  230.  —  Geologic  map  of  Coeur  d'Alene,  Ido.,  district. 
Geol.  Surv.,  Prof.  Pap.  62.) 


Prospects  or  mines 

not  of  "primary 

importance 


(After  Ransome,  U.  S. 


The  rocks  show  a  series  of  complex,  sometimes  overturned, 
folds  as  well  as  extensive  faults,  and  slaty  cleavage  has  been 
developed  in  all  except  the  quartzite. 

The  largest  ore  bodies,  although  wonderfully  persistent,  are  likely 
to  become  poor  at  depths  ranging  from  1000  to  2000  feet.  Three 
types  of  ore  bodies  are  recognized,  and  of  these,  which  are  described 
below,  the  first  is  the  most  important. 

1.  Lead-silver  deposits,  consisting  essentially  of  metasomatic 
fissure  veins,  formed  in  greater  part  by  replacement  of  siliceous 
sedimentary  rocks,  along  zones  of  fissuring,  and  carrying  mainly 
galena  and  siderite.  The  galena  may  first  replace  the  quartzite,  or 
siderite  may  replace  quartzite  first  and  then  be  replaced  by  galena. 

Pyrite  and  sphalerite  are  always  present,  and  tetrahedrite,  if 


SILVER-LEAD  ORES 


663 


found,  indicates  high  silver  values,  but  chalcopyrite  is  rare, 
dized  ores  occur  above. 


OxU 


The    lead-silver    veins,    which  He  mainly  in  that  portion  drained  by 
the  south  forks  of  the  Coeur  d'Alene    River    and  its    tributaries,  occur 

mostly  in  the  Burke  formation,  while 
a  few  are  found  in  the  Revett,  Wal- 
lace, St.  Regis,  and  Prichard. 

The  average  contents  of  ore  in  silver 
is  a  little  over  half  an  ounce  to  each 
per  cent  of  lead  per  ton.  In  1914  the 
Bunker  Hill  and  Sullivan  milling  ore 
assayed  10.35  per  cent  of  lead  and 
3.796  ounces  silver,  while  concentrates 
from  the  same  mine  averaged  62.91  per 
cent  lead  and  20.68  ounces  silver.  The 
tailings  assayed  2.675  per  cent  lead  and 
1.331  ounces  of  silver.  The  bulk  of 
the  ore  ranges  from  3  to  14  per  cent 
lead  and  2.5  to  6  ounces  silver  per 
ton.  Most  of  the  ore  in  the  district 
is  concentrated  to  50  or  60  per  cent 
lead. 


FIG.  231. —  Section  of  lead-silver  vein, 
Cocur  d'Alene,  Ido.  (1)  Country 
rock.  (2)  Sheared  rock.  (3)  Ga- 
lena and  siderite.  (4)  Fissure  with 
fine-grained  galena.  (5)  Barren, 
silicified  country  rock.  (After 
Finlay  Amer.  Inst.  Min.  Engrs., 
XXXIII.) 


The  rich  ores  and  concentrates  may  be  sent  to  Tacoma ;  San  Francisco ; 
Salida,  Colorado;  Helena,  Montana;  etc. 

In  the  mines,  the  galena  is  shown  to  have  a  vertical  range  of  at  least 
2600  feet. 

2.  Gold  deposits,  including  bed  veins,  fissure  veins,  and  placers  formed 
in  at  least  two  periods. 

The  productive  gold-quartz  veins  occur  near  Murray  and  are  bed 
veins,  following  stratification  planes  of  the  Prichard  formation.  They 
are  usually  a  foot  or  two  in  width  and  carry  quartz,  gold,  pyrite,  galena, 
sphalerite,  and  chalcopyrite,  with  occasional  bunches  of  scheelite.  The 
average  value  of  the  ore  probably  does  not  exceed  over  $7  per  ton. 

3.  Copper  deposits,  consisting  either  of  impregnations  along  certain 
quartzitic  beds  or  metasomatic  fissure  veins.     Only  the  former  type  is  of 
commercial  importance,  and  at    the  Snowstorm  mine  it  forms    an  im- 
pregnated zone  with  a  maximum  width  of  40  feet.      The  ore  is  chalcopyrite, 
bornite,  chalcocite,  etc.,  and  the  greater  part  runs  3  to  4  per  cent  copper, 
and  4.5  to  5.5  ounces  silver. 

Origin  of  lead-silver  ores.  —  It  is  believed  that  the  association  of 
the  ore  with  fissures  and  the  absence  of  irregular  deposits  indicate 
that  it  has  been  deposited  by  ascending  solutions,  moreover  the 
mineralogical  composition  of  the  ore  suggests  its  precipitation  from 
hot  solutions. 

These  solutions  are  thought  to  have  been  given  off  by  the  mon- 
zonite  in  vaporous  form,  producing  contact  metamorphism  and 


664  ECONOMIC   GEOLOGY 

depositing  ores  rich  in  sphalerite  and  pyrrhotite  associated  with 
garnet  and  biotite,  found  in  some  parts  of  the  district. 

Farther  away  from  the  intrusive  the  lead-silver  ores  were  depos- 
ited. It  is  probable  that  the  solutions  entered  the  stratified  rocks 
carrying  ferrous  carbonate  and  lead  sulphide,  and  not  only  filled  the 
open  spaces  but  replaced  the  quartzite. 

The  first  prospecting  occurred  in  this  district  about  1878,  and  subse- 
quent discoveries  in  1879  started  a  rush  to  this  region,  but  this  centered 
round  the  placers,  which  commanded  the  most  attention  even  up  to  1885 ; 
but  in  the  following  year  the  miners  awoke  to  an  appreciation  of  the  lead- 
silver  deposits,  and  the  building  of  a  railroad  into  the  district  in  1887  gave 
a  great  impetus  to  the  lode-mining  industry.  Since  then  the  Cceur  d'Alene 
has  been  an  important  producer,  in  spite  of  severe  though  temporary  set- 
backs due  to  labor  troubles  in  1892  and  1899. 

Park  City,  Utah  (22),  which  is  located  on  the  eastern  slope 
of  the  Wasatch  Range,  about  25  miles  southeast  of  Salt  Lake 
City  (Fig.  246),  has  made  Summit  County  famous  as  one  of 
the  important  mining  centers  of  this  country,  as  there  are  here 
large  bodies  of  rich  silver-lead  ores  carrying  minor  values  of 
gold  and  copper.  The  success  of  this  camp,  therefore,  depends 
more  or  less  on  the  condition  of  the  silver  and  copper  industry. 

The  geological  section  involves  a  series  of  limestones,  quartz- 
ites,  and  shales,  of  Carboniferous  to  Triassic  age,  the  series 
being  folded  into  an  anticline,  which  has  been  intruded  by 
diorite  rocks  of  post-Cretaceous  age.  Numerous  fault  fractures 
cross  the  district.  The  ores,  which  in  the  oxidized  zone  are 
cerussite,  anglesite,  azurite,  malachite,  etc.,  and  in  the  sulphide 
zone  are  galena,  sphalerite,  tetrahedrite,  and  chalcopyrite, 
occur  either  as  lodes  or  fissures,  or  as  bedded  deposits  in  lime- 
stones. The  latter,  which  supply  most  of  the  ore,  form  re- 
placements in  certain  strata  of  both  the  Upper  Carboniferous 
and  Permocarboniferous,  and  lie  between  siliceous  members 
as  walls.  Both  types  of  ore  deposit  are  frequently  associated 
with  porphyry. 

The  fissures  carry  either  silver  or  lead  with  or  without  zinc, 
and  copper  or  gold  with  some  silver.  The  replacement  ores  of 
the  limestones  hold  silver  and  lead  chiefly.  The  contact  ores 
contain  copper  and  gold  with  or  without  silver,  and  form 
irregular  bodies  in  metamorphic  limestone  adjacent  to  the 
igneous  rock. 


SILVER-LEAD   ORES 


665 


FIG.  232.  —  Map  of  Nevada,  showing  location  of  more  important  mining  districts. 

The  ordinary  crude  ore  carries  50  to  55  ounces  silver,  20  per  cent  lead, 
.04  to  .05  ounce  gold,  1.5  per  cent  copper,  10  to  18  per  cent  zinc.  Silver  is 
obtained  in  the  proportion  of  3  ounces  silver  to  each  per  cent  iron,  1  ounce 


666 


ECONOMIC  GEOLOGY 


silver  to  each  per  cent  lead,  and  .5  ounce  silver  to  each  per  cent  zinc. 
Bonanzas  are  known.  The  low-grade  ores  are  treated  at  the  concentrat- 
ing mill,  while  the  rich  ores  are  shipped  to  the  smelter. 

Tintic  District,  Utah  (23  and  26) .  —  This  district  lies  in  the 
Tintic  Mountains,  about  65  miles  southwest  of  Salt  Lake  City 
(Fig.  246).  The  rocks  of  the  district  include  over  12,000  feet 
of  Paleozoic  sediments,  folded  into  an  overturned  syncline, 
and  broken  by  faulting,  fissuring  and  sheeting.  Following  a 
period  of  erosion  there  was  a  period  of  igneous  activity  in  the 


Quartzife 
ftftyo/ife 
FIG.  233. — Geologic  map  of  Tintic  district,  Utah.     (Adapted  from  Tower  and  Smith.') 


At/uvium 

MINES  AMD  MINERALS. 


Tertiary,  yielding  rhyolites,  tuffs  and  breccias,  as  well  as  mon- 
zonitic  intrusions.  The  ore  deposits  include:  (1)  Thin  iron- 
manganese  deposits  on  the  limestone-igneous  rock  contacts; 
(2)  veins  of  silver-lead  ores  in  monzonite,  mostly  abandoned; 
and  (3)  limestone  replacement  deposits.  The  last,  or  most 
important,  occur  in  four  parallel  zones,  the  lead-silver  ores 
predominating  at  the  north  end  of  the  belts,  and  gold-copper 
ores  at  the  south  end,  while  zinc  is  found  in  both.  The  ores 
are  mainly  oxidized  ones,  weathering  having  reached  a  depth 
of  from  1500  to  2300  feet.  Crane  suggests  that  the  ore-bearing 
solutions  came  from  the  monzonite. 

The  Tintic  is  one  of  the  oldest  camps  in  the  state,  the  ore 


PLATE  LXII 


FIG.   1.  —  General  view  of  Rico,  Col.,  and  Enterprise  group  of  mines. 


JIG.  2.  —  View  of  a  portion  of  Mercur,  Ltah,  and  the  Mercur  mine. 

(667) 


668  ECONOMIC  GEOLOGY 

having  been  discovered  in  1869,  and  it  was  at  first  shipped  as 
far  as  Baltimore  and  Wales.  Since  then  mills  have  been  erected 
at  the  mines.  The  chief  towns  are  Eureka,  Mammoth,  Rob- 
inson, Silver  City,  and  Diamond. 

The  same  type  of  ore  occurs  in  Big  and  Little  Cotton  wood 
canons  and  Bingham  Canon  (Fig.  246),  the  latter  having  been 
worked  longer  than  those  of  the  Tintic  district.  The  camps 
lie  southeast  and  southwest  of  Salt  Lake  City,  and  the  ores 
are  oxidized  silver-lead  ones,  parallel  to  the  bedding  of  Car- 
boniferous limestones  and  the  underlying  quart zite.  Galena 
and  pyrite  occur  in  the  lower  workings  below  water  level. 

San  Francisco   district,    Utah    (23) .  —  This   is   an   area   pro- 
ducing essentially  silver-lead  ores,  as  well  as  copper  and  zinc, 
and   lies  in  Beaver   County,   Utah.     There   is   a   sedimentary 
series  of  Paleozoic  limestones,  shales,  and  quartzites,  covered 
by  a  thick  flow  of  lava,  and  intruded  by  quartz  monzonite  and 
related   rocks.     The  ore   deposits  consist  of:    (1)  Replacements 
along  fissures  in  quartz  monzonite,  as  in  the  Cactus  ore  zone, 
referred  to  under  Copper;    (2)  replacements  in  limestone,  con- 
sisting chiefly  of  lead-silver  with  smaller  amounts  of  gold  and 
copper,  and  also  some  contact  deposits;    (3)  replacement  fissure 
deposits  in  the  lava,  the  primary  ore  containing  chiefly  pyrite, 
galena,  and  sphalerite  in  a  gangue  of  quartz,  sericite  and  altered 
lava.     Interesting  replacements  of  one  sulphide  by  another  occur. 
Aspen,    Colorado  (ll).  —  The  ores  are  oxidized  and  occur  in 
highly  folded  and  faulted  Carboniferous  limestone,  although  the 
section  involves  rocks  ranging  in  age  from  Archaean  to  Mesozoic. 
Two  quartz  porphyries,  one  at  the  base  of  the  Devonian,  the  other 
in  the  Carboniferous,  are  present,  but  bear  no  special  relation  to  the 
ore. 

At  the  close  of  the  Cretaceous  the  rocks  were  folded  into  a  great 
anticline,  with  a  syncline  on  its  eastern  limit,  which  passed  into  a 
great  fault  along  Castle  Creek  west  of  the  mines.  Contemporaneous 
with  the  folding  there  were  also  produced  two  faults  parallel  to  the 
bedding  of  the  Carboniferous  dolomite,  while  at  the  same  time  much 
cross  faulting  occurred.  The  ore  is  found  chiefly  at  the  intersection 
of  these  two  sets  of  fault  planes,  and  Spurr  believes  that  the  ores 
were  deposited  by  magmatic  waters  ascending  vertically  along 
faults,  and  were  precipitated  by  a  reaction  between  the  solutions 
and  certain  wall  rocks,  chiefly  shale.  Mingling  of  solutions  at 


SILVER-LEAD   ORES 


669 


the  intersection  of  fissures  also  played  an  important  role  in  the 
formation  of  the  ore.  This  stronger  deposition  of  the  ore  at  the 
intersection  of  fault  planes  was  thought  by  Weed  to  be  due  to 
secondary  enrichment,  but  Spurr  finds  little  evidence  of  secondary 
sulphide  formation. 

On  account  of  the  intimate  association  of  the  dolomite,  quartz,  and 
barite  with  the  ore  their  origin  is  considered  as  similar. 

The  ores  are  peculiarly 
free  from  other  metals  except 
lead,  and  the  rich polybasite 
(Ag9SbS6)  ores  of  Smuggler 
Mountain  do  not  contain 
even  this. 

The  mining  camp  of  Aspen 
started  in  1879,  but  its  de- 
velopment for  a  time  was 
much  retarded  by  lawsuits. 
The  richer  ore  bodies  were 
not  discovered  until  1884, 
and  then  by  underground 
exploration,  for  owing  to  the 
heavy  mantle  of  glacial  grav- 
els their  outcrops  were  hid- 
den. Since  also  the  ore 
carries  no  iron  or  manganese, 
as  do  the  Leadville  ores,  its 
outcrop  may  be  inconspic- 
uous. 


I  GLACIAL  DRIFT 


•'  •  I  PARTING  QUARTZITE 


WEBER  FORMATION 


LEADVILLE  DOLOMITE 


YLN.E  FORMATION 


SAWATCH  FORMATION 


GRANITE 


The  railroads  did  not  reach 
the  camp  until  1887,  so  that 
during  the  first  few  years  of  its 
history  the  ore  had  to  be  carried 
out  on  burros. 

i  QUARTZ  PORPHYRY  In  both  Aspen  and  Smuggler 

FIG.  234. —  Section  of  ore  body  at  Aspen,  Col.    Mountains    long    tunnels    have 
(After  Spurr,  U.  S.  Geol.  Surv.,  Mon.  XXXI.)      been  run  for  drainage  and  haul- 
ing purposes.     The  Cowenhoven 

tunnel,  which  is  the  largest  of  these,  is  over  8300  feet  long,  and  taps  a 
number  of  mines.  Aspen  was  one  of  the  first  mining  camps  in  the  West 
to  install  electric  machinery  for  hoisting,  haulage,  etc.,  and  the  current 
was  cheaply  supplied  by  the  neighboring  water  power.  One  shaft  1000 
feet  deep  is  operated  electrically. 

At  the  present  day  the  larger  ore  bodies  are  worked  out,  but  the  camp 


670 


ECONOMIC   GEOLOGY 


is  still  an  active  producer.     From   1881  to  1895  it  produced  $63,653,989 
worth  of  silver. 


Rico,  Dolores  County,  Colorado  (3,  9,  10).  —  In  this  region  the 
mountains,  which  are  the  remains  of  the  structural  dome  rising 
above  the  Dolores  plateau  lying  in  the  San  Juan  region,  contain  a 
series  of  sedimentary  beds  ranging  from  Algonkian  to  Jurassic  in  age, 
which  have  been  uplifted  partly 
by  the  intrusion  of  igneous  rocks, 
as  stocks,  sills,  and  dikes,  and 
partly  by  upthrows  due  to  fault- 
ing. 

The  ore  occurs  as  lodes,  re- 
placements in  limestones,  stocks, 
and  blankets,  the  last  consist- 
ing usually  of  deposits  lying 
parallel  to  the  planes  of  bedding 
or  to  the  sheets  of  igneous  rock, 
and  known  locally  as  "  con- 
tacts," although  not  such  in  the 
true  sense. 

The  four  types  of  deposit  men- 
tioned may  pass  into  each  other. 
Most  of  the  ore  in  the  district 

has,    however,    Come    from    the    FIG.  235.  —  Diagrammatic  section   across 
blankets,    and   the   bulk   of  this  a  northeasterly  lode  at  Rico,  Col.,  show- 

has  been  found  in  the  Carbon-        £g '' ^J*6*"  of  ™:  A  WfrRansome, 

U.S.  GeoL  Surv.,  22d  Ann.  Rept.) 

nerous,   especially  in  the  Her- 

mosa  formation,  a  striking  feature  of  the  deposits  being  their  limited 

vertical  range. 

The  ores  are  primarily  galena,  often  highly  argentiferous  and 
associated  with  rich  silver-bearing  minerals.  In  many  deposits 
the  more  or  less  complete  oxidation  of  the  silver  ores  has  resulted 
in  powdery  masses,  often  very  rich  in  silver.  Below  the  zone  of 
oxidation,  the  veins  have  not  been  successfully  worked. 

The  bulk  of  the  ores  can  be  roughly  divided  into  pyritic  ores, 
usually  low  grade,  and  silver-bearing  galena  ores,  sometimes  con- 
taining rich  silver  minerals.  Quartz  is  the  commonest  gangue  min- 
eral, but  the  beautiful  pink  rhodochrosite  is  also  conspicuous. 

The  ore  deposition  is  believed  to  be  closely  associated  with  the 
igneous  intrusions  of  the  district,  especially  with  the  later  ones. 


SANDY  SHALE 
SANDSTONE 

BLACK  SHALE 
BLANKET 

BLANKET  LIMESTONE 
BLACK  SHALE 
SANDSTONE 
SANDY  SHALE 


SANDY  SHALE 

DSTONE 
SANDY  SHALE 
SANDSTONE 

SANDY  SHALE 
SANDSTONE 


SILVER-LEAD   ORES 


671 


Most  of  the  ore  produced  in  the  Rico  district  has  been  shipped 
crude  or  smelted  in  Rico  without  mechanical  concentration. 

Other  Occurrences. —  Argentiferous  lead  ores  also  occur  in  the  Ten  Mile 
district  (4),  in  Chaff ee  County,  and  along  the  Eagle  River  (8),  both  in 
Colorado. 

The  Eureka  district  (17,  18)  of  eastern    Nevada  (Fig.  232),  discovered 
in  1868,  is  chiefly  of  historic  importance.     The  ores  are  oxidized  lead-silver 
ores,  carrying  some  gold.     They  occur 
in  Cambrian  limestone  which  is  much 
faulted  and  crushed,  and  is  part  of  a 
Paleozoic  section  30,000  feet  thick. 

The  ore  is  associated  with  a  great 
fault,  and  is  oxidized  to  a  depth  of 
1000  feet.  There  are  two  mining  dis- 
tricts, Prospect  Hill  and  Ruby  Hill. 
Near  the  mines  are  great  prophyry 
masses  which  are  supposed  to  have 
afforded  the  ores.  Up  to  1882  the 
output  was  not  far  from  $60,000,000 
of  precious  metals  and  225,000  tons  of 
lead,  but  the  production  now  is  insig- 
nificant. 

Montana  contains  several 
lead-silver  ore  localities.  Those 
of  Neihart  (16)  occur  as  veins 
in  gneiss  and  igneous  rocks, 
the  ores  being  galena,  silver  sul- 
phides, and  some  blende.  The 
veins  are  best  denned  in  the  FlG-  236-  — Vein  filling  a  fault  fissure, 
gneiss,  and  are  mostly  replace-  %%&  T**1  7*7*  M^'  ***** 

J  Richard,    Amer.    Inst.    Mm.    Engrs., 

ment  deposits,  which  have  been      Trans.  XX vi.) 

subsequently       fractured      and 

secondarily  enriched.     Lead-silver  ores  also  occur  at  Glendale 

and    in    Jefferson    County.     Some    are    also   known   in   South 

Dakota,  and  at  Lake  Valley,  New  Mexico  (20,  21). 

Canada.  British  Columbia. —  The  Slocan  (28)  district,  which 
lies  between  the  Kootenay  and  Arrow  Lakes  of  the  Selkirk 
province  of  southern  British  Columbia,  contains  a  number  of 
silver-lead  and  zinc  deposits.  The  country  rock  includes  a 
series  of  interbedded  argillaceous  quartzites,  limestones  and 
slates  of  the  Slocan  series  (Carboniferous  ?),  which  have  been 
invaded  by  the  granitic  rocks  of  the  Nelson  (Jurassic  ?)  bath- 
olith.  Folding,  faulting,  and  lithologic  similarity  of  the  sedi- 


Rhodoohrosite    |  1  Quartz 


672  ECONOMIC  GEOLOGY 

ments  have  interfered  with  an  accurate  determination  of  the 
structural  details.  There  is  also  an  extensive  system  of  quartz 
porphyry  and  lamprophyre  dikes  which  seem  to  antedate  the 
vein  fissures.  The  ores  occur  in  veins,  in  part  breccia  filled, 
whose  length  varies  from  a  few  hundred  to  over  4000  feet, 
and  a  thickness  of  from  a  few  inches  to  over  50  feet.  Ore 
shoots  of  varying  size  and  sometimes  following  cross-fractures 
are  common.  The  chief  ore  minerals  are  galena,  sphalerite 
and  freibergite,  as  well  as  ruby  silver,  native  silver,  and  argentite. 
Chalcopyrite  and  pyrite  are  common  but  unimportant.  Sid- 
erite,  calcite,  and  quartz  form  the  gangue.  Weathering  effects 
are  shallow,  and  the  ore  seems  to  be  primary,  derived  probably 
from  the  Nelson  batholith. 

The  tenor  of  the  ores  ranges  from  7  per  cent  Pb  and  20 
ounces  per  ton  Ag  to  50-75  per  cent  Pb  and  80-175  ounces 
per  ton  Ag.  A  little  gold  is  found  in  some. 

Other  foreign  deposits.  —  Przibram,  Bohemia,  is  a  classic  locality, 
yielding  argentiferous  lead  ores.1  The  steeply  dipping  veins  occur  in  gray- 
wackes  and  clay  slates,  which  have  been  folded,  faulted,  and  intruded  by 
a  diorite  stock.  There  are  also  a  number  of  diabase  dikes,  which  follow 
the  veins  more  or  less  closely.  The  veins,  some  of  which  have  been  fol- 
lowed to  a  depth  of  over  3500  feet,  show  a  variable  thickness,  some  being 
25  feet.  The  common  ore  minerals  are  galena  and  blende,  with  some 
pyrite  and  chalcopyrite,  in  a  gangue  chiefly  of  calcite,  siderite,  and  quartz. 
Silver  sulphides  are  found  especially  in  the  oxidized  zone.  Where  the  veins 
pass  from  the  graywacke  into  the  diorite,  they  may  lose  their  galena  and 
silver,  and  take  up  stibnite  (Plate  XLI,  Fig.  1).  The  origin  is  not  perfectly 
clear,  but  was  possibly  connected  with  the  associated  intrusives. 

The  Freiberg,  Saxony,  district,  now x  practically  closed,  possesses  an 
historic  interest,  because  it  was  here  that  Werner  in  1791  developed  his 
theories  regarding  fissure  veins.  The  veins,  of  which  over  1100  are  known, 
occur  in  an  arch  of  biotite  gneiss,  and  are  separable  into  an  older  and  a 
younger  group.  The  former  contains  the  argentiferous  quartz,  pyritic  lead, 
and  argentiferous  ("noble  ")  lead  formation.  The  latter,  the  barytic-lead 
formation.2 

Clausthal,  Germany,3  is  also  well  known  on  account  of  its  series  of  veins 
carrying  argentiferous  galena,  blende,  and  subordinate  chalcopyrite,  pyrite, 
or  marcasite,  in  a  gangue  of  calcite-quartz  (Plate  XL),  or  barite-siderite. 
The  enclosing  formations  consists  of  Devonian  and  Carboniferous  clay 
slates  and  graywackes.  The  ores  are  found  filling  fissures  or  breccia  zones, 
and  while  unassociated  with  igneous  rocks,  may  be  genetically  connected 
with  the  granite  of  the  Brocken  Mountains  of  the  Harz. 

1  Vogt,  Krusch,  und  Beyschlag,  Lagerstatten,  II:  197,  1912. 

2  Ibid.,  II:  163,  1912. 

3  Ibid.,  II:  177,  1912. 


SILVER-LEAD  ORES  673 

Laurium,  Greece,1  is  another  locality  deserving  mention,  its  replace- 
ment deposits  of  ores  carrying  argentiferous  galena  and  sphalerite  in  crys- 
talline limestone.  In  Burma,  the  Bawdwin  mines  are  looked  upon  by  some 
as  a  coming  great  producer.  They  represent  replacements  of  ancient  vol- 
canic rocks.2 

Among  the  Mexican  silver-lead  deposits  those  of  the  Sierra  Mojada  3 
forming  replacement  deposits  in  Cretaceous  limestone  and  similar  ones 
of  the  Santa  Eulalia  district 4  are  of  importance. 


Deposits  Formed  at  Shallow  Depths 

United  States.  —  In  the  Creede  district  of  Colorado  (5), 
lead-silver  zinc  veins  occur  in  rhyolite,  and  rhyolite  breccias, 
the  ore  carrying  sphalerite,  galena,  pyrite,  etc.,  in  a  gangue 
of  manganiferous  quartz,  barite,  chlorite,  and  adularia. 

At  Lake  City,  Colo.  (6),  the  ores  fill  fissures  in  Tertiary 
flows  and  tuffs  of  the  Silverton  volcanic  series.  The  primary 
minerals  at  lower  levels  are  chiefly  quartz,  galena,  blende,  and 
pyrite,  while  at  shallower  depths  there  are  also  tetrahedrite, 
rhodochrosite,  barite,  and  jasperoid.  Secondary  minerals  are 
chiefly  pyrargyrite  and  galena,  as  well  as  some  chalcocite  and 
possibly  proustite.  Native  gold  occurs  in  the  upper  part  of 
the  sulphide  enrichment  zone.  The  mineralizing  solutions  came 
probably  from  a  quartz-monzonite  intrusion, 

REFERENCES    ON    SILVER-LEAD 

California:  1.  Knopf,  U.  S.  Geol.  Surv.,  Bull.  580-A:  1,  1914.  (Darwin 
dist.).  2.  Spurr,  U.  S.  Geol.  Surv.,  Bull.  208,  1903.  —  Colorado :  3. 
Cross  and  Spencer,  U.  S.  Geol.  Surv.,  21st  Ann.  Rept.,  II:  15,  1900. 
(Rico  Mts.).  4.  Emmons,  S.  F.,  Ibid.,  Ten  Mile  Atlas  Folio.  (Ten 
Mile  district.)  5.  Emmons,  W.  H.,  and  Larsen,  Ibid.,  Bull.  530:  42, 
1913.  (Creede.)  6.  Irving  and  Bancroft,  Ibid.,  Bull.  478,  1911. 
(Lake  City.)  7.  Kedzie,  Amer.  Inst.  Min.  Engrs.,  Trans.  XVI:  570, 
1888.  (Red  Mts.)  8.  Olcott,  Eng.  and  Min.  Jour.,  XLIII:  418, 
436,  1887  and  LIII:  545,  1892.  (Eagle  Co.,  Colo.)  9.  Ransome, 
U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  II:  229,  1902.  (Rico  Mts.)  10. 
Rickard,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXV:  906,  1896.  (Enterprise 
Mine,  Rico.)  11.  Spurr,  U.  S.  Geol.  Surv.,  Mon.  XXXI,  1898;  also 
Econ.  Geol.,  IV:  301,  1909.  (Aspen.)  —  Idaho :  12.  Hershey,  Min. 
and  Sci.  Press,  CIV:  750,  786  and  825,  1912.  (Wardner  district.) 

1  Vogt,  Krush  und  Beyschlag,  Lagerstatten,  II:  163,  1912. 

2  Hoffman,  Min.  Mag.,  XIV:  39,  1916. 

3  Malcolmson,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXII:     100,  1902. 

4  Weed,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXII:    396,  1902. 


674  ECONOMIC   GEOLOGY 

13.  Ransome  and  Calkins,  U.  S.  Geol.  Surv.,  Prof.  Pap.  62,  1908. 
(Coeur  d'Alene.)  14.  Umpleby,  Ibid.,  Bull.  540,  1914.  (Dome  dist.) 
—  Montana:  15.  Knopf,  Econ.  Geol.,  VIII:  105,  1913.  (Tourmaline 
lead  veins.)  16.  Weed,  U.  S.  Geol.  Surv.,  20th  Ann.  Kept.,  Ill:  271, 
1900.  (Neihart.)  —Nevada:  17.  Curtis,  U.  S.  Geol.  Surv.,  Mon.  VII, 
1884.  (Eureka.)  18.  Hague,  Ibid.,  Mon.  XX,  1892.  (Eureka.)  19. 
Pack,  Sch.  M.  Quart.,  XXVII:  285  and  365,  1910.  (Pioche.)  —  New 
Mexico:  20.  Clark,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXIV:  138. 
(Lake  Valley.)  21.  Lindgren,  Graton  and  Gordon,  U.  S.  Geol.  Surv., 
Prof.  Pap.  68,  1910. —Utah:  22.  Boutwell,  U.  S.  Geol.  Surv.,  Prof. 
Pap.  77,  1912.  (Park  City.)  23.  Butler,  U.  S.  Geol.  Surv.,  Prof. 
Pap.  80,  1913,  also  Econ.  Geol.  IX:  413,  1915.  (San  Francisco.)  23a. 
Crane,  Amer.  Inst.  Min.  Engrs.,  Bull.  106:  2147,  1915.  (Tintic.) 
24.  Lindgren,  Econ.  Geol.,  X:  225,  1915.  (MineraPn  and  enrich't, 
Tintic.)  25.  Loughlin,  Econ.  Geol.,  IX:  1,  1914.  (Oxid.  zinc  ores, 
Tintic.)  26.  Tower  and  Smith,  19th  Ann.  Rept.,  Ill:  601,  1899. 
(Tintic.)  —  Canada:  27.  Argalls  and  others,  Rept.  of  Com.  on  Zinc 
Resources  Brit.  Col.,  Mines  Branch,  1906.  28.  LeRoy,  Internat. 
Geol.  Congr.,  Canada,  1913,  Guidebook  9.  (Slocan.)  29.  Schofield, 
Can.  Geol.  Surv.,  Summ.  Rept.  for  1911:  158,  1912.  (St.  Eugene 
mine,  Moyie.)  30.  Schofield,  Econ.  Geol.,  VII:  351,  1912.  (E.  Koo- 
tenay,  Brit.  Col.)  31.  See  also  annual  reports  of  Minister  of  Mines, 
British  Columbia, 


CHAPTER  XIX 
GOLD  AND  SILVER 

GOLD  and  silver  are  obtained  from  a  variety  of  ores,  in  some  of 
which  the  gold  predominates,  in  others  silver,  while  in  still  a  third 
class  these  two  metals  may  be  mixed  with  the  baser  metals,  lead, 
copper,  zinc,  and  iron.  Few  gold  ores  are  absolutely  free  from  silver, 
and  vice  versa,  so  that  a  separate  treatment  of  the  two  is  more  or  less 
difficult;  however,  some  lead-silver  ores,  although  they  may  carry 
some  gold,  are  sufficiently  prominent  to  be  discussed  as  a  separate 
type,  and  have  been  referred  to  in  the  preceding  chapter. 

Ore  Minerals  of  Gold.  —  Gold  occurs  in  nature  chiefly  as  native 
gold,  mechanically  mixed  with  pyrite,  or  as  telluride  such  as  calav- 
erite  (AuTe2;  Au,  39.5  per  cent;  Ag,  3.1  per  cent;  Te,  57.4  per 
cent).1 

Gold  is  also  found  at  times  in  chalcopyrite,  arsenopyrite,  and 
stibnite,  but  not  as  a  rule  in  such  large  amounts  as  may  be  shown  by 
pyrite.  Sphalerite  and  pyrrhotite  sometimes  carry  it. 

The  gold-bearing  sulphides,  as  well  as  the  tellurides,  are  of 
primary  character,  although  auriferous  chalcopyrite  might  be 
formed,  by  secondary  enrichment.  4 

Native  gold  may  occur  in  the  primary,  secondary  enrichment, 
or  oxidized  zones.  The  tellurides,  which  are  usually  associated 
with  pyrite,  are  widely  distributed,  though  not  so  abundant, 
but  not  always  recognized;  indeed  by  some  they  are  mistaken 
for  sulphides. 

Ore  Minerals  of  Silver.  —  The  minerals  which  may  serve  as 
ores  of  silver,  together  with  the  percentage  of  silver  they  con- 
tain, are  shown  in  the  table  on  the  following  page. 

Galena,  sphalerite,  pyrite,  chalcopyrite,  and  chalcocite  may  all 
be  and  frequently  are  argentiferous,  but  in  most  ore  deposits 
is  usually  favors  the  first  named. 

Of  the  ore  minerals  above  mentioned,  the  most  common  primary 
ones  are  argentiferous  galena,  sphalerite,  and  pyrite,  while  native 
silver  and  the  sulphides  and  arsenides  are  less  common. 

1  Other  tellurides  are  sylvanite  and  krennerite. 
675 


676 


ECONOMIC   GEOLOGY 


MINERAL  1 

COMPOSITION 

Ag 

Native  silver   
Argentite,  silver  glance 
Pyrargyrite,  ruby  silver     .     . 
Proustite,  light  ruby  silver     . 
Stephanite,  brittle  silver,  black 
silver        

Ag 

Ag2S 
3Ag2S,  SboS3 
3Ag2S,  As2S3 

5Ag2S,  Sb2S3 

100. 
87.1 
59.9 
65.5 

68.5 

Polybasite             

Ag9SbS6 

75.6 

Cerargyrite,  horn  silver     .     . 
Bromyrite  
Embolite     

AgCl 
AgBr 
Ag(ClBr) 

75.3 
57.4 
64.5 

lodyrite      

Agl 

46.0 

Tetrahedrite  (Freibergite).     . 

4(Cu2Ag2FeZn)S,Sb2S3 

Variable; 
usually  present; 
may  be  high. 

In  the  oxidized  zone,  silver  chloride  is  the  most  abundant, 
and  native  silver  less  so,  while  the  iodides  and  bromides  are 
quite  rare  and  formed  only  under  certain  conditions. 

The  secondary  enrichment  ores  include  native  silver,  argentite, 
stephanite,  tetrahedrite,  pyrargyrite,  and  proustite. 

Mode  of  Occurrence.  —  Most  of  the  gold  and  silver  mined  in 
the  United  States  is  obtained  from  fissure  veins,  or  closely  related 
deposits  of  irregular  shape  (113),  in  which  the  gold  and  silver 
ores  have  been  deposited  from  solution,  either  in  fissures  or  other 
cavities,  or  by  replacement.  Considerable  gold  and  a  little 
silver  are  obtained  from  gravel  deposits,  and  some  true  contact- 
metamorphic  deposits  are  known.  Gold  has  been  found  to  occur 
in  rare  instances  as  an  original  constituent  of  igneous  rocks 
(l,  15,  18)  and  also  metamorphic  ones  (19),  but  there  are  no 
known  deposits  of  commercial  value  belonging  to  this  type. 

The  gold-  and  silver-bearing  fissure  veins  include  two  prom- 
inent types  (113),  viz.:  (1)  the  quartz  veins,  and  (2)  the  propy- 
litic  type,  in  which  the  metasomatic  alteration  of  the  wall  rock 
is  often  propylitic.  In  the  quartz- vein  type  silver  is  present 
usually  in  but  small  quantities,  while  in  the  propylitic  type  the 
silver  often  is  an  important  constituent.  Veins  of  intermediate 
character  may  also  occur. 

While  the  mode  of  occurrence  of  gold  and  silver  is  quite  vari- 
able, the  character  of  the  wall  rock  is  equally  so,  gold  and 
silver  ores  being  found  in  either  sedimentary  or  igneous  rocks, 
and  along  the  contact  between  the  two,  showing  that  the  kind 
of  rock  exerts  little  influence,  except  perhaps  where  replace- 

1  Other  less  common  ones  are  polyargyrite,  pearcite,  miargyrite,  etc. 


GOLD  AND  SILVER  677 

ment  has  been  active.  On  the  other  hand  the  influence  of  locality 
is  much  stronger,  for  it  has  been  found  that  many  gold-  and 
silver-bearing  deposits  are  closely  associated  with  masses  of 
igneous  rock,  the  most  common  of  these  being  diorite,  monzonite, 
quartz-monzonite,  granodiorite,  while  true  granites  are  rare  as 
associates.  A  second  large  class  of  vein  systems  shows  a  close 
association  with  lavas  of  recent  age,"  and  the  telluride  ores  rather 
favor  these  (8). 

Weathering  and  Secondary  Enrichment.  —  The  superficial  al- 
teration of  gold  ores  differs  somewhat  from  that  of  deposits 
containing  ores  of  the  other  metals.  In  quartz  veins  with  aurif- 
erous pyrite,  the  change  of  the  latter  to  limonite  leaves  a  rusty 
quartz  with  nuggets  or  threads  of  free  gold,  and  leaching  may 
remove  most  of  the  iron. 

The  conditions  under  which  gold  is  removed  by  the  influence 
of  manganese  are  discussed  on  p.  480. 

Telluride  ores  weather  in  a  somewhat  characteristic  manner, 
the  product  being  free  gold.  This  may  be  of  earthy  appearance 
and  faint  brownish  color,  or  consists  of  aggregates  of  extremely 
small  crystals  of  gold  which  form  a  spongy  mass,  or  a  thin  film 
on  the  surface  of  the  rock. 

Silver  sulphides  are  changed  to  chlorides,  and  native  silver 
may  also  be  formed.  In  the  weathered  portion  of  some  silver- 
bearing  deposits,  silver  bromides  and  iodides  are  also  fcund. 

Penrose  has  suggested  1  that  such  ore  bodies  were  in  the 
vicinity  of  saline  deposits,  where  haloid  compounds  were  dis- 
solved by  the  soil  waters  that  penetrate  the  ores.  Keyes,  how- 
ever, believes  that  the  prevailing  source  of  saline  materials  is 
the  wind-blown  dust  produced  by  disintegrative  processes  so 
predominant  in  arid  regions  (9). 

Downward  secondary  enrichment  has  evidently  occurred  in 
a  number  of  silver  and  silver-gold  deposits.  According  to 
W.  H.  Emmons  (7),  all  deposits  in  which  gold  appears  to  have 
migrated  include  manganiferous  ores.  In  deposits  carrying  both 
metals,  especially  where  chlorides  form,  secondary  silver  min- 
erals are  likely  to  be  precipitated  as  bonanzas  near  the  surface, 
while  gold  is  carded  deeper,  but  if  chlorides  are  not  formed  in 
manganiferous  deposits,  silver  may  be  carried  deeper  than  gold. 
Abundant  pyrrhotite  is  said  to  rapidly  halt  the  downward  mi- 
gration of  both  gold  and  silver.  In  copper  deposits  where  silver 

1  Jour.  Geol.  II:  1894. 


678  ECONOMIC   GEOLOGY 

and  gold  migrate  downward,  these  are  deposited  chiefly  in  the 
upper  part  of  the  secondary  sulphide  zone.  Many  deposits 
of  rich  silver  ore  and  some  of  rich  gold  ore  terminate  down- 
ward in  low-grade  sphalerite  ores. 

Geological  Distribution.  —  Gold  and  silver  ores  have  been 
deposited  at  a  number  of  different  periods  in  the  geological 
history  of  the  continent,  notably,  in  the  pre-Cambrian,  Cam- 
brian, Cretaceous,  and  Tertiary  ages. 

Some  of  the  Appalachian  veins  are  probably  early  Paleozoic, 
and  those  of  Nova  Scotia  are  post-Cambrian.  Silver  ores  show 
much  the  same  geological  range. 

The  geological  distribution  is  referred  to  in  more  detail  under 
Metallogenetic  Epochs  in  Chapter  XIV. 

Classification.  —  A  classification  of  gold  and  silver  ores  is  in 
any  event  attended  with  more  or  less  difficulty.  Divisions 
based  on  geological  and  structural  characters  would  for  many 
purposes  be  more  satisfactory,  while  for  commercial  or  metal- 
lurgical work  a  grouping  according  to  metallic  contents  is  per- 
haps  more  desirable. 

The  following  classification  according  to  the  associations  of 
the  ores  is  sometimes  used  in  the  United  States. 

1.  Placers  or  Gravel  Deposits.  —  These  serve  chiefly  as  a  source 
of  native  gold,  but  may,  and  often  do,  contain  a  little  silver, 
mud!  of  which  is  never  separated  from  the  ore  in  which  it  occurs. 
These  gravels  are  derived  chiefly  from  quartz  veins  of  Mesozoic 
age  in  the  Pacific  coast  region,  and  to  a  less  extent  from  pre- 
Cambrian  veins  of  the  Appalachian  region  and  Black  Hills 
of  South  Dakota.  Some  are  also  derived  from  veins  in  Tertiary 
lavas,  but  these  usually  contain  the  metals  in  such  a  finely 
divided  condition,  or  in  such  combination,  that  they  do  not  readily 
accumulate  in  stream  channels. 

Large  quantities  cf  placer  gold  are  obtained  from  Alaska 
and  California. 

Taking  all  sources,  we  see  that  placer  gold  is  obtained  by  dredging, 
drift-mining,1  hydraulicking,  and  sluicing,  as  well  as  in  small  amounts  from 
dry  placers  in  the  southwest  and  beach  gravels  of  California  and  Oregon. 

Dredging,  which  was  started  in  New  Zealand  about  1882,  and  first 
profitably  tried  in  the  Bannock  district  of  Montana  in  1893,  is  now  of  great 
importance,  the  modern  bucket  elevator  dredge  (often  electrically  driven) 

1  In  decreasing  quantity  from  frozen  ground  in  Alaska,  but  still  in  considerable 
amounts  from  buried  channels  in  California. 


GOLD  AND   SILVER  679 

being  capable  of  excavating  as  much  as  10,000  cubic  yards  daily,  and  the 
buckets  each  having  a  capacity  of  16  cubic  feet.  The  total  value  of  gold 
in  millions  of  dollars  produced  in  this  manner  by  several  states  up  to  date 
is:  Montana,  6|;  Idaho,  3;  Colorado,  2|;  Alaska,  10;  California,  over  71. 

2.  Dry  or  Siliceous  Ores.  —  These  include:    (a)  The  gold  and 
silver  ores  proper;    (6)  fluxing  ores  carrying  considerable  quan- 
tities of  iron  and  manganese  oxides  with  small  gold  and  silver 
contents;    and    (c)    precious-metal   bearing   ores    with    copper, 
lead  and  zinc  in  small  amounts.     Colorado,  California,  Nevada, 
South  Dakota,  and  Alaska  have  been  the  largest  gold  producers 
of  this  type. 

The  siliceous  gold  ores  are  in  part  free  milling  (amalgamating)  as  Alaska, 
California,  and  Oregon;  in  part  both  amalgamating  and  concentrating; 
in  part  simply  concentrating,  as  parts  of  Colorado  and  Arizona;  in  increasing 
part  all-sliming  and  cyaniding;  and  in  part  smelting. 

A  great  deal  of  the  silver  from  the  gold-silver  siliceous  ores  is  obtained 
with  the  gold  by  amalgamation  and  cyanidation,  the  silver  being  recovered 
by  refining  the  mill  bullion.  The  remainder  is  obtained  by  smelting  rich 
ores  and  refining  copper  or  lead  bullion  produced. 

Nevada  yields  now  over  one-half  the  silver  production,  but 
much  also  conies  from  Colorado. 

The  siliceous  ores  are  of  varying  age.  Those  of  California, 
Oregon,  and  Alaska  are  Mesozoic  and  associated  chiefly  with 
quartz— monzonite,  granodiorite,  and  diorite.  Another  great 
class  of  post-Miocene  age,  found  chiefly  in  Colorado,  Nevada, 
and  Montana,  is  associated  with  Tertiary  lavas  and  charac- 
terized by  Bonanzas.  The  most  productive  ones  carry  fluorite 
and  normally  also  tellurides.  In  some,  gold  may  predominate; 
in  others,  silver.  A  third  class,  of  pre-Cambrian  age,  is  found 
in  the  Atlantic  states,  Wyoming,  and  South  Dakota,  the  last 
mentioned  including  the  famous  Homestake  mine. 

3.  Copper  ores,  usually  with   over  2J   per  cent  copper,  but 
with  less  in  the  case  of  the  western  disseminated  ores  and  those 
of  Lake  Superior. 

The  largest  gold  producers  are  those  of  Utah,  Arizona,  Nevada, 
and  Montana.  The  silver  production  comes  from  the  elec- 
trolytic refining  of  Michigan  copper,  and  blister  copper  pro- 
duced by  smelting.  The  great  disseminated  deposits  of  Utah, 
Arizona,  Nevada,  and  New  Mexico  are  yielding  increasing  quan- 
tities, while  the  vein  deposits  of  Butte,  Mont.,  are  also  im- 
portant. 


680  ECONOMIC   GEOLOGY 

The  gold-  and  silver-bearing  copper  ores  exhibit  great  dif- 
ferences in  form  and  age;  neither  do  all  the  occurrences  yield 
much  gold  or  silver,  and,  moreover,  they  are  of  more  importance 
as  gold  producers,  silver  being  less  often  associated  with  the 
copper. 

4.  Gold-  and  Silver-bearing  lead  ores,  containing  4J  per  cent 
or  more  of  lead.     The  gold  is  obtained  chiefly  from  Utah  and 
Colorado.     The  silver  comes  mainly  from  the  lead-silver  ores 
of  Creur  d'Alene,  Idaho,  Utah  (chiefly  Park  City  and  Tintic), 
Colorado  (Leadville  and  Aspen) .      Most  of  the  output  is  obtained 
by  the  de-silverization  of  lead  bullion. 

5.  Copper-lead  or  Copper-lead-zinc  Ores.  —  These    are   unim- 
portant as  compared  with  the  others.     The  gold  supply  is  small, 
and  the  main  silver  supply  is  from  Colorado  and  Nevada. 

6.  Zinc  ores,   containing  at  least  25  per    cent   zinc.     These 
yield  little  gold,  and  the  silver  which  is  obtained  mainly  as  a 
by-product  from  the  smelting  of  zinc  concentrates  is  obtained 
chiefly  from  Nevada,  Montana,  and  Arizona. 

Extraction.  —  Since  gold  and  silver  ores  vary  so  in  their  mineralogical 
associations  and  richness,  the  metallurgical  processes  involved  in  their  ex- 
traction are  varied  and  often  complex. 

Those  ores  whose  precious  metal  contents  can  be  readily  extracted  after 
crushing,  by  amalgamation  with  quicksilver,  are  termed  free-milling  ores. 
This  includes  the  ores  which  carry  native  gold  or  silver,  and  often  repre- 
sent the  oxidized  portions  of  ore  bodies.  Others  containing  the  gold  as 
telluiide  or  containing  sulphides  of  the  metals,  are  known  as  refractory  ores 
and  require  more  complex  treatment.  These,  after  mining,  are  sent  direct 
to  the  smelter  if  sufficiently  rich,  but  if  not  they  are  oiten  crushed  and 
mechanically  concentrated.  The  smelting  process  is  also  used  lor  rrixed 
ores,  the  latter  being  often  smelted  primarily  for  their  lead  or  copper  con- 
tents, from  which  the  gold  or  silver  is  then  separated.  While  in  some  cases 
there  are  smelters  at  the  mines,  still  there  is  a  growing  tendency  towards 
the  centralization  of  the  industry,  and  large  smelters  are  now  located  at 
Denver,  Salt  Lake  City,  etc.,  which  draw  their  ore  supply  from  many  mining 
districts. 

Low-grade  ores  may  first  be  roasted,  and  the  gold  then  extracted  by 
leaching  with  cyanide  or  chlorine  solutions.  The  introduction  of  the  cyanide 
and  chlorination  processes,  which  are  applied  chiefly  to  gold  ores,  has  per- 
mitted the  working  of  many  deposits  formerly  looked  upon  as  worthless, 
and  in  some  regions  even  the  mine  dumps  are  now  being  worked  over  for 
their  gold  contents.  It  is  estimated  that  in  1914  $28,629,147  worth  of  gold 
bullion  was  recoverd  by  cyanidation.  The  chief  fields  are  in  the  Cripple 
Creek  region  of  Colorado;  the  De  Lamar  district,  Idaho;  Marysville, 
Montana;  Bodie,  California;  and  in  Arizona. 


GOLD  AND   SILVER 


681 


The  most  important  gold-milling  centers  of  the  United  States  are  the 
Mother  Lode  district  of  Caliiornia;  the  Black  Hills,  South  Dakota,  and 
Douglas  Island,  Alaska. 

The  value  of  ore  and  bullion  is  determined  from  a  sample  assay,  and  the 
smelter,  in  paying  the  miner  for  his  ore,  allows  for  gold  in  excess  of  $1  per 
ton  of  ore  at  the  coining  rate  of  $20.67  per  ounce,  and  for  silver  at  New 
York  market  price,  deducting  5  per  cent  in  each  case  for  smelter  losses. 
Lead  and  copper  are  paid  for  in  the  same  manner,  as  are  also  iron  and  man- 
ganese, if  there  is  a  sufficient  quantity  present.  No  allowance  is,  however, 
made  for  zinc,  and,  in  fact,  a  deduction  is  made  if  it  exceeds  a  certain  per 
cent. 

Distribution  of  Gold  and  Silver  Ores  in  the  United  States 

(Fig.   237) .  —  Gold  ores  are  widely  distributed  in  .the  Cordil- 
leran  and  Appalachian  regions,  while  the  silver  ores  are  found 


FIG. 


237.  —  Map  showing  distribution  of  gold  and  silver  ores  in  the  United  States. 
(Adapted  from  Ransome,  Min.  Mag.,  X.) 


chiefly  between  the  Great  Plains  and  Pacific  coast  ranges,  ex- 
clusive of  the  Colorado  plateau  region.  This  occurrence  in  two 
widely  separated  areas  is  brought  out  in  an  interesting  manner 
in  Fig.  237. 

More  than  one-half  of  the  United  States  production  of  gold 
comes  from  three  states — California,  Colorado,  and  Nevada. 
In  these,  however,  the  ores  vary  widely  in  their  mineralogical 
associations,  the  gold  occurring  mostly  in  combination  with 
silver,  lead,  copper,  and  zinc  ores,  but  also  at  times  free,  or,  in 
the  most  productive  district,  as  a  telluride. 


682  ECONOMIC   GEOLOGY 

The  Pacific  belt,  excluding  Alaska,  supplies  about  25  per 
cent  of  the  total  amount  of  gold  produced,  the  famous  Mother 
Lode  region,  mentioned  later,  being  the  most  important  producer. 
Alaska  yields  about  17  par  cent,  and  the  Basin  Range  province 
nearly  22  per  cent,  collected  from  widely  separated  deposits  in 
Utah,  Nevada,  Arizona,  and  New  Mexico,  and  in  which  the 
gold  is  associated  with  copper,  silver,  or  lead. 

About  49  per  cent  of  the  silver  obtained  in  the  United  States 
comes  from  the  Rocky  Mountain  region,  Idaho  alone  yielding 
nearly  one-fifth,  while  Montana  supplies  a  little  less.  The  Basin 
Range  province  furnishes  something  under  two-fifths,  nearly 
one-half  of  this  coming  from  Utah,  especially  from  the  Park 
City  mines  near  Salt  Lake  City1  (114). 

The  gold  and  silver  occurrences  of  the  United  States  can  be 
grouped  under  five  regions  as  follows: 

1.  Cordilleran  Region.  —  This  includes  several  types  geolog- 
ically arranged  as  follows:  (a)  belt  of  Pacific  coast  Cretaceous 
gold  quartz  ores,  characterized  by  ores  with  free  gold,  and 
auriferous  sulphides,  extending  along  the  Pacific  coast  from  Lower 
California  up  to  the  British  Columbia  boundary.  The  deposits 
belonging  to  this  are  especially  important  in  California,  but 
farther  north,  in  Oregon  and  Idaho,  the  veins  in  many  cases 
have  been  covered  up  by  the  lava  flows  of  the  Cascade  Range, 
and  those  known  in  that  region  differ  somewhat  from  the  Cali- 
fornia deposits  in  containing  many  mixed  silver-gold  ores  and 
also  veins  carrying  auriferous  sulphides  without  free  gold.  The 
ores  of  this  belt  are  all  of  undoubted  Mesozoic  age,  and  are 
accompanied  by  many  extensive  placer  deposits,  which  have 
been  derived  by  the  weathering  down  of  the  upper  parts  of 
the  quartz  veins,  the  portions  now  remaining  in  the  ground 
representing  probably  but  the  stumps  of  originally  extensive 
fissure  veins  (113). 

Among  the  deposits  of  this  belt  two  groups  stand  out  in  some 
prominence,  namely,  those  of  the  so-called  Mother  Lode  dis- 
trict and  of  Nevada  County. 

b.  Late  Cretaceous  or  Early  Tertiary  deposits,  occupying  a 
broad  zone  in  the  central  and  eastern  part  of  the  Cordilleran 
region,  and  -delding  gold  ores  of  varying  character.  While 
they  differ  ii*  °  and  characters  from  the  Pacific  coast  ores, 

1  These  estimates  are,  of  course,  only  approximate. 


GOLD  AND   SILVER 


683 


and  those  of  the  belt  next  to  be  mentioned,  nevertheless  they 
are  not  absolutely  separated  from  them  geographically. 

The  Mercur,  Utah  (Fig.  246),  and  Leadville,  Colorado  (Fig. 


FIG.  238.  —  Map  of  California,  showing  location  of  more  important  mining  districts 

249),  deposits,  the  latter  referred  to  under  lead  and  zinc,  are 
included  under  this  type. 

The  northward  continuation  of  this  belt        ^jld-bearing  veins 


684  r      ECONOMIC  GEOLOGY 

in  Idaho  and  Montana  presents  somewhat  different  types  of 
deposits,  for  there  the  veins  are  causally  connected  with  great 
batholiths  of  Mesozoic  granite ;  and  while  the  veins  resemble 
those  of  the  Pacific  coast  in  the  quartz  filling  and  free  gold  con- 
tents, they  differ  from  the  latter  in  containing  more  silver,  and 
often  large  quantities  of  sulphides  with  little  free  gold.  In 
fact,  in  their  geologic  relations  they  are  intermediate  between 
the  quartz  vein  and  propylitic  type.  Of  special  prominence  are 
those  of  Marysville,  Montana  (so),  and  Idaho  Basin,  Florence, 
etc.,  in  Idaho.  This  difference  is  more  marked  in  the  Montana 
occurrences,  in  which  the  gold  becomes  subordinate  and  is  ob- 
tained as  a  by-product  in  silver  mining. 

(c)  Eastern  belt  of  Tertiary  gold-silver  veins,  of  greater  im- 
portance than  the  preceding  class  and  characteristic  of  regions 
of  intense  volcanic  acticity.  The  veins  cut  across  andesite 
flows,  or  more  rarely  rhyolite  and  basalt.  They  may  be  entirely 
within  the  volcanic  rocks,  or  the  fissures  may  continue  down- 
ward into  the  underlying  rocks,  which  have  been  covered  by 
the  extrusive  masses.  Many  of  these  Tertiary  deposits  belong 
to  the  propylitic  class,  showing  characteristic  alterations  of  the 
wail  rock.  The  ores  are  commonly  quartzose,  and  though 
either  gold  or  silver  may  predominate,  the  quantities  of  the 
two  metals  are  apt  to  be  equal.  Bonanzas  are  of  common  occur- 
rence, and  on  this  account  the  mines  may  be  very  rich  but  short- 
lived; still,  the  workable  ore  in  many  extends  to  great  depths; 
but  is  less  rich  than  nearer  the  surface.  Extensive  and  rich 
placers  are  rarely  found  in  the  Tertiary  belt  of  veins,  for  the 
reason  that  the  fine  distribution  of  the  gold  is  not  favorable 
to  its  concentration  and  retention  in  stream  channels.  Deposits 
of  this  type  are  worked  in  a  number  of  states,  including  Colo- 
rado, Nevada,  Arizona,  New  Mexico,  and  Idaho.  Colorado 
leads  in  the  production  of  gold  ores,  for  in  no  state  are  the 
Tertiary  deposits  of  the  propylitic  type  developed  on  such  a 
scale. 

2.  Black  Hills  Region,  the  ores  which  are  found  chiefly  in 
the  northern  Black  Hills,  including:  (a)  Auriferous  schists  in 
pre-Cambrian  rocks;  (b)  Cambrian  conglomerates;  (c)  refrac- 
tory siliceous  ores;  (d)  high-grade  siliceous  ores;  and  (e)  placers. 
Of  these,  the  first  and  third  are  the  most  important. 

The  surface  placers,  being  the  most  easily  discovered,  were 
developed  first,  followed  by  the  conglomerates  at  the  base  of 


GOLD  AND  SILVER  685 

the  Cambrian.1  These  are  found  near  Lead,  occupying  depres- 
sions in  the  old  schist  surface,  and  the  material  is  thought  to 
have  been  derived  from  the  reef  formed  by  the  Homestake 
ledge  in  the  Cambrian  sea.  These  deposits  are  of  interest  as 
being  probably  the  oldest  gold  placers  known-  in  the  United 
States.  The  fact,  however,  that  the  matrix  of  the  gold-bearing 
portion  of  the  conglomerate  is  pyrite  rather  than  quartz,  and 
the  occurrence  of  the  gold  along  fractures  stained  by  iron,  has 
led  some  to  believe  that  the  gold  has  been  precipitated  chem- 
ically by  the  action  of  iron  sulphide  and  is  not  a  detrital  product. 

3.  Eastern  Crystalline  Belt  (114).  —  Gold,  with  some  silver, 
has  been  found  in  the  rocks  of  this  belt  from  Vermont  to  Ala- 
bama, but  the  deposits  are  of  little  importance  except  in  North 
Carolina  (96-97),  South  Carolina  (106,  107),  Georgia  (69-71),  and 
Alabama  (22,  23),  in  other  words,  in  the  southern  Appalachian 
and  Piedmont  region;  but  even  in  this  part  of  the  area  the 
deposits  are  not  found  everywhere,  but  are  restricted  to  three 
belts  (Becker),  viz.:  (1)  the  Georgia  belt,  extending  from  Mont- 
gomery, Alabama,  across  northern  Georgia  to  North  Carolina; 
(2)  the  South  Mountains  region  of  North  Carolina;  (3)  the 
Carolina  belt,  lying  to  the  eastward  of  the  others,  and  extend- 
ing from  South  Carolina  northeastward  through  Charlotte, 
North  Carolina,  and  continued  in  Virginia;  at  least  the  Vir- 
ginia deposits  lie  in  part  in  the  line  of  strike  of  this  zone. 

Geologic  Comparisons  (i3a).  —  It  will  be  seen  from  the  pre- 
ceding pages  that  the  ores  of  South  Dakota  and  the  Appala- 
chians belong  to  an  older  group  whose  age  ranges  from  pre- 
Cambrian  to  Paleozoic,  and  to  which  belong  also  the  gold  ores 
of  Nova  Scotia,  Ontario,  and  Quebec.  Here  too  belong  many 
of  the  deposits  of  Brazil  and  other  eastern  and  northern  South 
American  countries.  Representatives  of  this  group  are  known 
also  in  other  countries,  notably  Australia. 

The  other  North  American  occurrences  belong  to  a  younger 
group  of  late  Mesozoic  to  Quaternary  age.  Few  representatives 
of  this  class  are  found  in  Canada,  but  they  yield  the  enormous 
silver  supply  of  Mexico,  and  many  are  known  and  worked  in 
the  Andean  region  of  South  America. 

Other  important  occurrences  are  worked  in  Hungary,  New 
Zealand,  etc. 

1  These  are  referred  to  as  cement  mines,  owing  to  their  partly  cemented 
character. 


686  ECONOMIC   GEOLOGY 

Contact-metamorphic  Deposits 

Gold  and  silver  may  be  present  in  small  amounts  in  copper 
deposits  of  this  class,  but  ore  bodies  of  this  type  containing  the 
noble  metals  as  important  constituents  are  rare. 

Such  a  case  has,  however,  been  recorded  in  the  Cable  mine 
in  the  Philipsburg  quadrangle  of  Montana  (?8o),  where  the 
ore  body  occurs  in  limestone  surrounded  by  quartz-monzonite. 
The  chief  non-metallic  minerals  are  calcite,  quartz,  barite, 
and  dolomite,  with  pyrite,  chalcopyrite,  pyrrhotite,  arsenopyrite, 
magnetite,  specularite,  and  gold  as  the  primary  metallic  ones. 
Contact  silicates  also  occur. 

Of  considerably  greater  importance  is  the  ore  deposit  of  the 
Nickel  Plate  Mine  at  Hedley,  British  Columbia  (135),  which 
is  of  a  rare  type.  The  ore  deposits  occur  at  the  contact  of 
dikes  and  sheets  of  gabbro  in  Carboniferous  limestones  (Fig. 
239)  which  are  interbedded  with  quart zite,  shale  and  volcanic 
tuffs.  The  ore  bodies,  which  are  of  irregular  outline,  contain 
arsenopyrite,  with  chalcopyrite,  pyrrhotite,  blende,  pyrite,  native 
gold  and  tetradymite  (I^Tes).  The  gangue  includes  garnet, 
epidote,  diopside,  amphibole,  quartz,  calcite,  and  axinite.  The 
gold  averages  $11.00  per  ton. 

Other  deposits  of  this  group  are  auriferous  tellurides  at  Elk- 
horn,  Montana,  and  deposits  of  argentiferous  and  auriferous 
bornite  at  Chiapas,  Mexico.1 


Deposits  of  the  Deep-vein  Zone 

These  include  deposits,  chiefly  in  the  form  of  fissure  veins, 
precipitated  under  high-temperature  conditions,  either  in  cavities 
or  by  replacement.  In  most  of  the  deposits  belonging  to  this 
class,  gold  is  more  abundant  than  silver. 

United  States.  —  Gold  and  silver  ores  of  this  class  are  not 
very  abundant  in  the  United  States,  but  include  some  well- 
known  deposits. 

Silver  Peak,  Nev.  (92).  —  The  deposits  at  this  locality  are 
so  closely  associated  with  igneous  rocks  that  Spurr  classed  them 
as  magmatic  segregations  (p.  92),  but  some  may  feel  that 
they  might  be  better  put  in  the  deep-vein  zone  class.  The  ore 
occurs  in  lenticular  masses  and  fissure  veins  of  quartz,  which 

1  McCarty,  Inst.  Min.  and  Met.,  London,  Trans.  IV:  169,  1895. 


PLATE  LXIII 


FIG.  1.  —  Mill  of  Nickel  Plate  mine,  Hedley,  B.  C.     Mines  on  ridge  in  back- 
ground.     (H.  Ries,  photo.) 


FIG.  2.  —  Virginia  City,  Nev.,  Mt.  Davidson  in  rear,  on  whose  lower  slope  the 
Comstock  Lode  outcrops.     (H.  Ries,  photo.) 

(687) 


688 


ECONOMIC   GEOLOGY 


grade  into  alaskite  and  this  in  turn  into  granite,  so  that  the 
quartz   represents   the   end-phase   of  the   intrusion.     The   gold 


ri"  <M*  CO  •* 


690 


ECONOMIC   GEOLOGY 


occurs  chiefly  in  the  quartz.     Paleozoic  limestone  is  the  main 
country  rock. 

South  Dakota.  —  The  gold  ores  of  the  Homestake  belt  (109, 
110),  which  are  the  most  important  in  the  Black  Hills,  occur 
in  a  broad  zone  of  impregnated  schists,  containing  many  quartz 
lenses,  alternating  with  dikes  of  fine-grained  rhyolite,  which 
al&o  formed  sheets  in  the  Cambrian  sediments  overlying  the 
schists,  and  now  remain  as  a  resistant  cap  on  many  of  the  sur- 
rounding ridges  (Fig.  240).  The  ore,  which  is  all  low-grade, 
averaging  about  $4  per  ton,  is  usually  a  mixture  of  quartz, 


I  CEMENT  MINES 


FIG.  240.  —  Section  of  Homestake  belt  at  Lead,   S.  Dak.,   showing  realtion  of 
ancient  and  modern  placers  to  Homestake  lode.     (From  Min.  Mag.,  XI.) 

pyrite,  and  occasionally  other  minerals  having  no  definite  con- 
nection with  it,  occupying  a  zone  in  the  Algonkian  rocks  which 
shows  greater  hardness,  irregularity  of  structure,  and  mineral- 
ization than  the  surrounding  schists.  The  boundaries  are  poorly 
defined,  and  superficial  examination  may  fail  to  distinguish 
between  ore  and  barren  rock.  In  the  upper  levels  the  ore  seems 
to  be  with  the  dikes,  but  diverges  from  them  in  depth,  and 
there  is  apparently  no  genetic  relation  between  the  two.  In 
the  earlier  days  the  ore  encountered  was  oxidized  and  free- 
milling,  but  the  appearance  of  sulphides  with  depth  has  neces- 
sitated the  introduction  of  the  cyanide  method  of  extraction. 
The  ore  was  originally  worked  as  an  open  cut  (PL  LXIV),  but 
later  by  underground  methods. 

In  1914  the  output  of  this  mine  was  1,587,774  short  tons  of 
ore  milled,  with  $6,160,161  of  bullion  recovered,  the  ore  value 
per  ton  being  $3.87. 

Appalachian  Belt  (114).  —  The  crystalline  belt  of  the  southern 
Appalachians  contains  numerous  quartz  veins,  some  of  which 


GOLD  AND   SILVER  691 

are  of  lenticular  character.  There  may  also  be  replacement 
deposits  in  silicified  schist.  The  placers  derived  from  these 
quartzose  ores  have  yielded  considerable  gold  in  the  past, 
notably  in  Georgia,  Virginia,  and  North  Carolina,  but  the  vein 
mining  has  been  less  productive.  It  is  doubtful  whether  all 
the  veins  belong  to  the  deeper-vein  zone,  some  probably  having 
been  formed  at  intermediate  depths. 

In  the  Carolina  belt  Graton  (106)  states  that  the  quartz 
veins  with  more  or  less  pyrite  occur  in  dense  metamorphic 
rocks,  and  most  commonly  in  amphibole  or  gabbro  closely 
related  to  it,  and  formed  by  the  filling  of  fracture  spaces.  The 
veins,  which  are  irregular  and  have  a  steep  dip,  conform  usu- 
ally somewhat  closely  to  the  strike  and  dip  of  the  inclosing 
rocks. 

Similar  occurrences  are  found  in  the  other  belts  of  the  southern 
Appalachians,  and  some,  as  those  at  Gold  Hill,  North  Carolina, 
have  shown  copper  with  depth,  so  that  they  were  worked  for 
both  metals. 

The  replacement  type,  which  is  important  in  the  Carolina  belt, 
is  less  common  but  more  productive  than  the  preceding,  and 
with  one  or  two  exceptions  is  found  in  volcanic  rocks,  mostly 
tuffs.  The  porous  nature  and  easily  alterable  character  of  these, 
especially  the  tuffs,  has  allowed  widespread  penetration  and  re- 
placement by  the  ore  solutions,  which  deposited  chiefly  silica  and 
pyrite. 

The  ore  bodies  are  usually  large,  and  range  from  40  or  50  to  hun- 
dreds of  feet  in  length,  and  20  to  several  hundred  feet  in  width ;  but 
their  outline  is  rudely  lenticular. 

At  the  Haile  Mine  in  South  Carolina,  which  belongs  to  this  type, 
the  country  rock  is  a  quartz-sericite  schist,  which  has  been  derived 
by  foliation  from  a  porphyry  tuff  which  had  an  original  well-bedded 
structure  that  is  still  preserved  in  some  cases.  The  silicification 
appears  to  correspond  in  intensity  with  the  amount  of  foliation, 
although  in  cases  of  extreme  silicification  all  traces  of  former  struc- 
ture have  been  quite  destroyed,  and  the  rock  is  simply  a  massive 
siliceous  hornstone.  Several  dikes  of  diabase  cut  the  schist. 

The  ore  consists  of  large  lenses  of  altered  tuff,  which  have  been 
silicified  and  pyritized,  the  two  processes  having  gone  on  at  the  same 
time,  so  that  the  rock  now  consists  of  a  fine-grained  aggregate  of 
quartz  and  pyrite  with  scattered  fibers  of  sericite.  The  replace- 
ment is  not  uniform.  The  gold  occurs  (1)  mainly  as  native  gold 


692 


ECONOMIC  GEOLOGY 


originally  deposited,  (2)  free  gold  derived  from  oxidation  of  the 
inclosing  pyrite,  and  (3)  gold  in  pyrite. 

This  mine,  which  has  been  worked  more  or  less  continuously 
since  about  1830,  has  been  one  of  the  most  important  producers 
in  the  southern  Appalachian  region. 

Other  occurrences.  —  The  copper  deposits  of  the  Cactus  Mine, 
Utah;  Copperopolis  Calif;  and  Meadow  Lake,  Calif,  yield  not 
a  little  gold,  but  copper  as  well,  and  are  mentioned  under  the 
latter. 

Alaska  (24).  —  Although  gold  has  been  known  to  occur  in 
Alaska  since  the  early  part  of  the  century,  and  was  even  worked 
in  1860,  its  production  is  not  definitely  stated  until  1880,  when 


LEGEND 

.Gold  placers 

4. Gold  and  silver  lodes 

n  Copper 

+  Tin  lodes 

X  Tin  placers 

•  Coal 

o  Petroleum 


FIG.  241.  —  Map  showing  mineral  deposits  of  Alaska.      (After  Brooks,  U.  S.  Geol. 

Surv.,  Bull.  250.) 

it  was  added  to  the  list  of  gold-producing  regions,  with  an  out- 
put of  $20,000,  which  since  that  time  has  increased  many  times 
over,  but  not  steadily,  until  it  reached  a  maximum  of  $22,036,794 
in  1906,  and  had  dropped  to  $15,764,259  in  1914. 

The  first  gold  was  discovered  on  the  islands  of  the  Alexander 
Archipelago  and  along  the  adjoining  coast,  but  subsequently  pros- 
pectors found  their  way  into  the  interior,  the  first  strikes  there  being 


GOLD  AND   SILVER 


693 


made  in  British  Columbia  near  the  head  of  the  Stikine  River.  These 
were  followed  by  discoveries  in  the  Yukon  Valley,  especially  along 
some  of  the  tributaries  known  as  Birch  Creek,  Mission  Creek,  and 
Forty  Mile  Creek.  In  1896  still  richer  discoveries  were  made  along 
the  Klondike  River,  and  within  one  year  the  yield  of  this  region 
had  exceeded  the  purchase  price  of  Alaska.  Other  discoveries 
have  since  followed  rapidly. 

At  the  present  time  approximately  68  per  cent  of  the  value 
of  the  gold  produced  in  Alaska  is  obtained  from  placers,  31  per 
cent  from  quartz  ores,  and  the  balance  from  copper  ores. 

Auriferous  Lodes  (32).  —  The  gold  quartz  lodes,  which  are 
most  prominent  along  the  coast  (Fig.  241),  were  first  discovered 
near  Sitka  in  1897,  but  the  first  important  production  came  from 
the  Tread  well  mine  on  Douglas  Island  southeast  of  Juneau 
(32)  in  1882. 

The  geology  of  this  region  bears  in  many  ways  a  strong  re- 
semblance to  the  California  gold  belt,  but  the  ores  differ  in 


FIG.  242.  —  Sketch  map  of  Douglas  Island,  Alaska.     (After  Spencer,  U.  S.  Geol. 

Surv.,  Bull.  259.) 


origin.  The  section  involves  a  series  of  steeply  dipping  slates 
and  greenstone  and  diorite  dikes.  The  ore  bodies  (Figs.  242, 
243)  are  dikes  of  albite-diorite,  permeated  with  metallic  sulphides 
and  carrying  small  amounts  of  gold,  with  a  hanging  wall  of  green- 
stone and  a  foot  wall  of  black  slate.  The  veinlets,  which  are 
thought  to  have  been  formed  by  shearing  stresses  incident  to 
epeirogenic  movements,  occur  in  two  sets  of  fractures  at  right 


694  ECONOMIC   GEOLOGY 

angles  to  each  other.  Spencer  believes  that  the  mineralization 
has  been  caused  by  hot  ascending  solutions  of  magmatic  origin. 
Secondary  concentration  is  not  in  evidence,  and  it  is  thought  that 
the  depth  to  which  the  ores  can  be  worked  will  depend  more 
on  the  increased  cost  of  mining  at  great  depths  than  on  exhaustion 
of  the  ore. 

The  workings  on  Douglas  Island  extend  for  a  distance  of 
7000  feet.  Gold  also  occurs  in  quartz  veins  along  the  cost. 

The  southeastern  Alaska  gold  ores  are  placed  in  this  group 
because  of  the  character  of  the  gangue  minerals  and  alteration 
of  the  wall  rocks. 


,-•          '  "w  r-    BUWL 

DIORITE         /  SLATERS  GREENSTONE    <      CLA 


SCALE    1,050   FEET=1    INC 


FIG.  243.  —  Cross  section  through  Alaska  Treadwell  mine  on  northern  side  of 
Douglas  Island.     (After  Spencer,  U.  S.  Geol  Surv.,  Bull.  259.) 

Canada.  —  A  number  of  auriferous  quartz  veins  are  known 
in  Ontario  (126,  127,  137)  and  Quebec  (138),  but  few  of  them 
are  of  much  importance. 

The  best  known  deposits  are  those  of  the  Porcupine  district, 
Ontario.  The  ore  bodies  which  occur  in  the  metamorphosed 
sediments  of  the  Temiskaming  series,  and  schistose  volcanics 
of  the  Keewatin,  consist  of  lenticular  veins,  irregular  veins  and 
domelike  masses  of  quartz,  carrying  native  gold  together  with 
pyrite  and  some  other  metallic  sulphides,  with  which  are  asso- 
ciated calcite,  dolomite,  sericite,  chlorite,  tourmaline,  and  quartz. 
The  gold  and  pyrite  appear  to  have  been  deposited  about  the 
same  time,  and  especially  in  the  crushed  portions  of  the  quartz 
or  the  schist  bordering  these.  The  annual  production  of  this 
district  now  exceeds  $4,000,000. 

Other  gold  quartz  veins  are  known  in  the  Lake  of  the  Woods 
(145)  and  Rainy  Lake  districts  (137),  also  at  Lakes  Abitibi 
(145)  and  Larder  Lake  (147). 

The  deposits  at  Rossland,  B.  C.,  referred  to  under  copper, 
also  yield  an  appreciable  quantity  of  gold. 


GOLD  AND   SILVER  695 

Other  Foreign  Deposits.  —  West  Australia  l  contains  several  gold  mining 
districts,  that  of  Kalgoorlie  being  the  most  important,  the  others  including 
Pilbarra,  Murchison,  and  Mount  Margaret.  The  rocks  are  chiefly  crystalline 
schists  derived  from  igneous  rocks  and  granites  together  with  altered  sedi- 
mentaries,  but  the  gold  deposits  are  found  chiefly  in  the  schists.  Two 
types  are  recognized,  viz.:  (1)  Quartz  veins  in  amphibolite,  or  at  its  con- 
tact with  granite,  and  (2)  lodes,  formed  by  ore  deposition  along  shear  zones. 
The  first  class  carries  native  gold,  galena,  blende,  pyrrhotite,  chalcopyrite, 
arsenopyrite,  stibnite,  bismuthinite,  pyrite,  scheelite,  chlorite,  calcite,  sericite, 
and  sometimes  tourmaline;  the  latter  has  native  gold,  tellurides,  pyrite, 
chalcopyrite,  blende,  galena,  pyrargyrite,  magnetite,  siderite,  ankerite, 
sericite,  tourmaline,  albite,  etc.  The  wall  rock  bordering  the  lodes  has 
been  noticeably  altered. 

Brazil  contains  several  deep  gold  mines  in  the  province  of  Minas  Geraes, 
of  which  the  Morro  Velho  is  not  only  the  most  important,  but  also  the 
deepest  in  the  world,  having  reached  a  vertical  depth  of  5800  feet.2  The 
ore  deposits  are  quartz  veins  in  Archaean  schists,  gneisses  and  granites,  or 
in  sedimentary  schists  and  quartzites. 

India.  —  The  pre-Cambrian  veins  in  crystalline  schists  of  the  Kolar 
gold  fields  in  Mysore,  India,  also  belong  in  this  group,3 


Deposits  Formed  at  Intermediate  Depths 

This  group  includes  a  number  of  auriferous  quartz  veins, 
carrying  free  gold,  pyrite,  and  even  other  sulphides,  but  lacking 
the  silicates  characteristic  of  the  deep-vein  zone.  The  quartz 
veins  do  not,  as  a  rule,  show  a  high  silver  content.  Alteration 
of  the  wall  rocks  sometimes  occurs,  resulting  in  the  development 
of  sericite,  carbonates,  and  pyrite. 

United  States.  —  California.  Mother  Lode  Belt  (45,  52).- 
This  includes  a  great  series  of  quartz  veins,  beginning  in  Mari- 
posa  County  and  extending  northward  for  a  distance  of  112 
miles.  The  veins  of  this  system  break  through  black,  steeply 
dipping  slates  and  altered  volcanic  rocks  of  Carboniferous  and 
Jurassic  age  (Fig.  244),  and  since  they  are  often  found  at  a  con- 
siderable distance  from  the  granitic  rocks  of  the  Sierra  Nevada, 
they  have  apparently  no  genetic  relation  with  them.  The  veins, 
which  occur  either  in  the  slate  itself  or  at  its  contact  with  diabase 
dikes,  show  a  remarkable  extent  and  uniformity,  due  to  the 

1  Bulletins  of  West  Austral.  Geol.  Surv.,  especially  Nos.  6,  14,  15,  20,  22,  23, 
45,  46,  51,  56;  also  Lindgren,  Econ.  Geol.,  I:  530,  1905;   Maclaren  and  Thomson, 
Min.  and  Sci.  Pr.,  CVII:  45,  1913;  Larcombe,  Ibid.,  CXI:  238,  1915. 

2  Harder  and    Leith,  Jour.  Geol.,  XXIII:    341  and  385,  1915;    also  Lindgren 
Amer.  Inst,  Min.  Engrs.,  Bull.  112:  721,  1916. 

3  Hatch,  Geol.  Surv.,  Ind.,  Mem.  33,  1901. 


696 


ECONOMIC  GEOLOGY 


fact  that  in  the  tilted  layers  of  the  slates  there  were  planes  of 
weakness  for  the  mineral-bearing  solution  to  follow.  The  ore 
is  native  gold  or  auriferous  pyrite  in  a  gangue  of  quartz,  and 
the  average  value  may  be  said  to  vary  from  $3  to  $4  up  to  $50 
or  $60  per  ton.  The  veins  often  split  and  some  of  the  mines 
have  reached  a  depth  of  several  thousand  feet. 


ji  nt 

"  /  ^ 

7f  [*• \jftf 


,'     ams    I     I          ams  I    Co 


FIG.  244. —  Map  and  section  of  portion  of  Mother  Lode  district,  Calif.  Pgv,  river 
gravels,  usually  auriferous  ;  Ng,  auriferous  river  gravels.  Sedimentary  rocks  : 
Jm,  mariposa  formation  (clay,  slate,  sandstone,  and  conglomerate)  ;  Cc,  cala- 
veras  formation  (slaty  mica  schists) .  Igneous  rocks  :  Nl,  latite  ;  Nat,  andesite 
tuffs,  breccia,  and  conglomerate ;  mdi,  meta-diorite ;  Sp,  serpentine ;  ma, 
meta-andesite  ;  ams,  amphibole  schist.  (From  U.  S.  GeoL  Surv.,  Atlas  Folio, 
Mother  Lode  sheet.) 

Nevada  County  (48).  —  In  Nevada  County  the  mines  of  Grass 
Valley  and  Nevada  City  are  likewise  quartz  veins  (PI.  LXV,  Fig.  2) 
but  they  occur  along  the  contact  between  a  granodiorite  and  dia- 
base porphyry,  as  well  as  cutting  across  the  igneous  rock  (Fig.  245). 
Two  systems  of  fault  fissures  occur,  and  in  these  the  ore  is  found 
either  in  native  form  or  associated  with  metallic  sulphides.  The 
width  of  the  vein  averages  from  2  to  3  feet,  and  the  lode  ore 
generally  occurs  in  well-defined  bodies  or  pay  shoots.  The  vein 
filling  was  deposited  by  hot  solutions,  and  while  the  wall  rocks 


PLATE  LXV 


FIG.  1.  —  Kennedy  mine  on  the  Mother  Lode,  near  Jackson,  Calif. 


FIG.  2.  —  Auriferous  quartz  veins  in  Maryland  mine,  Nevada  City,  Calif.     (After 
Lindgren,  U.  S.  Geol.  Surv.,  17th  Ann.  RepL,  III.) 

(697) 


698 


ECONOMIC   GEOLOGY 


contain  the  rare  metals  in  a  disseminated  condition,  Lindgren  (48) 
believes  that  the  ores  have  been  leached  out  of  the  rocks  at  a  con- 
siderable depth.  The  mines  at  Nevada  City  and  Grass  Valley 
have  been  large  producers  of  gold  and  some  silver.  Placer  mines 
have  furnished  a  small  portion  of  the  product,  but  at  the  present 
day  these  latter  are  of  little  importance. 

In  Oregon,  the  quartz  veins  are  worked  in  Baker  County,  which 
is  the  most  important  gold-producing  region  of  the  state  (104,  105). 
Gold  ores  with  sulphides  in  quartz  gangue  are  worked  in  the  Monte 
Cristo  district  of  Washington  (122) 


|V_>/|  METAMORPHIC 
h^M  SCHIST  AND  DIABASE 


I  GRANODIORITE 

a.  MERRIFIELD  VEIN    6.URAL  VEIN  C.SLATE  VEIN 


FIG.  245.  —  Section  illustrating  relations  of  auriferous  quartz  veins  at  Nevada 
City,  Calif.     (After  Lindgren,  U.  S.  Geol.  Surv.,  17th  Ann.  Rept.,  II.) 

South  Dakota.  Siliceous  Cambrian  Ores  (109,  111).- — The 
refractory  siliceous  Cambrian  ore  is  found  in  the  region  between 
Yellow  Creek  and  Squaw  Creek,  and  yielding  about  two-thirds 
as  much  gold  as  the  Homestake.  The  deposits,  which  occur 
as  replacements  in  a  siliceous  dolomite  (Fig.  247),  are  found  at 
two  horizons,  one  immediately  overlying  the  basal  Cambrian 
quartzite,  and  the  other  near  the  top  of  the  Cambrian  series. 
The  ore  forms  flat  banded  masses  known  as  shoots,  and  varying 
in  width  from  a  few  inches  to  300  feet.  It  is  overlain  by  shale 
or  eruptive  rock,  and  associated  with  a  series  of  vertical  fractures, 
made  prominent  by  a  slight  silicification  of  the  wall  rock.  These 
fractures,  which  are  termed  verticals,  are  supposed  to  have  con- 
ducted the  ore-bearing  solutions. 

The  ore  is  a  hard,  brittle  rock,  composed  of  secondary  silica, 
with  pyrite  and  fluorite,  and  at  times  barite,  wolframite,  stib- 
nite,  and  jarosite.  Its  contents  range  from  $3  or  $4  per  ton 
to  in  rare  cases  $100  per  ton,  with  an  average  of  $17.  Other, 


700 


ECONOMIC  GEOLOGY 


but    less   important,   siliceous  ores  occur  in  the  Carboniferous 
rocks. 
Mercur,  Utah.  —  The  gold-silver  mines  of   the  Mercur   (117) 


FIG.  246.  —  Map  of  Utah,  showing  location  of  more  important  mining  districts. 

district  in  Utah  form  perhaps  the  most  important  occurrence  in 
this  central  zone.  Here  the  Carboniferous  limestones,  shales,  and 
sandstones,  representing  about  12,000  feet  of  sediment,  are  folded 
into  a  low  anticline  (Fig.  248) .  Near  the  center  of  the  section  is 
the  great  blue  limestone,  carrying  an  upper  and  a  lower  shale  bed. 


GOLD   AND   SILVER 


.701 


Quartz  porphyry  has  intruded  the  limestone,  and,  at  two  places 
especially,  spread  out  laterally  in  the  form  of  sheets,  on  whose  under 
side  the  ore  is  found,  the  silver  ores  under  the  lower  sheet,  the  gold 
/  i 


FIG.  247.  —  Typical  section  of  siliceous  gold  ores,  Black  Hills,  S.  Dak.     (After 
Irving,  U.  S.  GeoL  Surv.,  Prof.  Pap.  26.) 

ores  under  the  upper  one,  about  100  feet  above  the  first.  The 
silver  ore  is  cerargyrite  and  argentiferous  stibnite  in  a  silicified  belt 
of  the  limestone.  The  gold  is  native  and  occurs  in  a  belt  of  resid- 
ual contact  clay,  near  northeast  fissures  cutting  the  limestone, 
being  oxidized  in  places  and  accompanied  by  sulphides  in  others. 


EAGLE   HILL  PORPHYRY 
GREAT  BLUE  LIMESTONE 


GREAT   BLUE  LIMESTONE 


LOWER  LIMESTONE 


FIG.  248.  —  Section  at  Mercur,  Utah.     (After  Spurr,  U.  S.  Geol.  Surv., -16th  Ann. 

Kept.,  II.) 

The  ore  runs  1-19  ounces  of  silver  per  ton,  and  2-3  ounces  of  gold, 
with  a  gangue  of  quartz,  barite,  limonite,  and  arsenical  sulphides. 
The  silver  minerals  are  thought  to  have  been  deposited  by  heated 
solutions  which  came  up  along  the  igneous  sheet  some  time  after 
its  intrusion,  and  the  deposition  of  the  gold  ore  is  believed  to  have 
taken  place  some  time  after  the  silver  was  deposited.  Some  doubt 


702 


ECONOMIC   GEOLOGY 


exists  as  to  the  exact  source  of  the  ascending  waters,  but  in  all 
probability  they  were  derived  from  some  deep-seated  cooling 
mass  of  igneous  rock.  The  ores  are  especially  suited  to  the 
cyanide  treatment. 

Georgetown,  Colorado  (68).- — Clear  Creek  County  (Fig.  249), 
in  which  Georgetown  lies,  is,  next  to  Gilpin  County,  the  oldest 
mining  district  in  Colorado,  if  not  the  entire  Rocky  Mountain 
region. 

There  are  a  number  of  mining  camps  in  this  area,  including 
Georgetown,  Idaho  Springs,  Silver  Plume,  Central  City,  etc., 


FIG.  249.  —  Map  showing    approximate  distribution  of  the  principal  silver,  lead 
and  gold  regions  of  Colorado.     (After  Spurr.) 

but  the  only  area  which  has  been  described  in  detail  is  that 
included  in  the  Georgetown  quadrangle.  The  conditions  here, 
however,  are  in  a  general  way  similar  to  those  existing  in  other 
parts  of  the  district. 

The  earliest  rocks  of  the  district  consist  of  a  series  cf  pre- 
Cambrian  schists,  the  oldest  ones  (Idaho  Springs  formation) 
being  probably  of  sedimentary  origin,  but  the  later  ones  meta- 
morphosed igneous  rocks. 

This  series  has  been  successively  injected  by  about  eight  types  of 
plutonic  rocks  ranging  from  granites  to  diorites. 


GOLD   AND   SILVER 


703 


was 


Following  these,  in  late  Cretaceous  or  early  Tertiary,  came  the 
intrusion  of  a  series  of  porphyry  dikes  which  are  as  varied  in 
their  composition  as  the  plutonics.  These  porphyries  are_.of 
more  than  local  interest  because  they  form  part  of  a  wide  ir- 


704  ECONOMIC   GEOLOGY 

regular  zone  that  extends  in  a  general  northeast-southwest  direc- 
tion from  Boulder  to  Leadville  and  then  on  to  the  San  Juan  region 
(Fig.  249,).  It  will  thus  be  seen  that  many  important  mining 
districts  lie  within  it. 

The  ore-bearing  fissure  veins  (PI.  LXVI),  which  may  occur 
in  any  of  the  older  schistose  rocks  of  the  district,  are  divisible 
into  two  groups,  viz.,  argentiferous  blende-galena  ones  with  little 
gold,  and  auriferous  pyrite  veins  with  or  without  silver.  The 
former  predominate  in  the  Georgetown  region,  the  latter  south- 
west of  Idaho  Springs,  but  the  two  types  of  ore  are  occasionally 
known  to  occur  in  the  same  vein.  Both  types  of  veins  are  seen 
to  show  a  general  agreement  in  trend  and  distribution  with 
the  porphyry  dikes  (Fig.  250),  and  the  vein  formation  is  thought 
by  Spurr  not  only  to  have  followed  the  porphyry  intrusions, 
but  to  show  characteristic  petrographic  associations.  That  is, 
the  silver-galena -blende  veins  are  related  to  dikes  of  alaskite 
porphyry,  granite  porphyry,  quartz -monzonite  porphyry,  and 
dacite;  the  auriferous  pyrite  veins  with  bostonite,  alaskite, 
quartz  monzonite,  biotite  latite,  and  alkali  syenite. 

The  two  classes  of  veins  show  the  same  primary  minerals 
(galena,  blende,  and  pyrite),  but  the  proportions  of  them  in 
each  differ,  and  they  have  the  same  bonanzas,  wall  rocks,  and 
gangue  minerals  (mainly  quartz). 

It  is  suggested  by  Spurr  that  the  alteration  of  the  wall  rocks 
was  caused  by  descending  atmospheric  waters,  changing  them 
to  mixtures  of  quartz,  sericite,  carbonates,  and  kaolin,  and  the 
gangue  minerals  have,  moreover,  come  from  the  walls;  but 
while  the  source  of  the  metals  in  the  silver  veins  is  in  doubt, 
Spurr  considers  that  the  metalliferous  minerals  of  the  gold  veins 
were  contributed  by  magmatic  waters. 

Crosby  has  questioned  whether  the  gold  and  silver  veins 
represent  distinct  classes,  and  points  out  that  since  the  former 
outcrop  at  low  levels,  they  may  simply  represent  the  basal 
portions  of  silver  veins,  these  being  known  to  outcrop  only  at 
the  higher  points  in  the  district. 

Gilpin  County  (54) .  —  The  rock  formations  are  somewhat 
similar  to  those  of  the  Georgetown  quadrangle,  as  are  also  the 
gold-silver  ore  veins,  which  are  grouped  by  Bastin  and  Hill 
as:  (1)  Pyritic  ores;  (2)  galenarspnalerite  ores;  and  (3)  com- 
posite ores,  carrying  the  minerals  of  both  the  other  classes,  and 
being  the  result  of  dual  mineralization.  Most  of  the  veins 


GOLD  AND  SILVER 


705 


occupy  zones  of  minor  faulting  the  ore  deposition  having  been 
partly  by  filling  and  partly  by  replacement. 


Fort 
organ 


!      G       A       R       F'~    I* 


FIG.  251.  —  Map  of  Colorado,  showing  location  of  mining  regions.     (After  Rickard, 
Amer.  Inst.  Min.  Engrs.  Trans.,  1904.) 

Canada.  Nova  Scotia  (140,  146).  —  The  gold  veins  of  this 
province,  which  form  a  belt  along  the  south  coast,  occur  in 
folded  Cambrian  (?)  slates  and  quartzites  which  have  been 
intruded  by  Silurian  (?)  granites.  The  veins,  which  are  often 
saddle-shaped,  are  usually  found  along  the  axes  of  plunging 
anticlines,  and  most  of  them  are  parallel  to  the  stratification. 
Some  show  a  strong  crenulation  supposed  to  be  of  post-mineral 
character,  and  small  veins  often  pass  outward  from  the  main 
ones.  The  ore  mineral  is  native  gold,  in  quartz  gangue,  and 
associated  with  pyrite,  chalcopyrite,  galena,  blende,  and  arseno- 
pyrite.  While  the  ore  is  supposed  to  be  due  to  cavity  filling, 
Faribault  believes  that  the  veins  are  younger  than  the  granite, 
but  Rickard  holds  that  they  are  later. 

Other  Foreign  Deposits.  —  Victoria.1  This  colony  contains  two  well- 
known  gold  districts,  viz.,  those  of  Bendigo  and  Ballarat.  In  both  we  find 

1  Rickard,  Amer.  Inst.  Min.  Engrs.,  Trans.  XX:  463,  1891;  Lindgren,  Eng.  and 
Min.  Jour.,  Mar.  9,  1905;  Vogt,  Krusch  und  Beyschlag,  Lagerstatten,  II:  107, 
1912. 


706 


ECONOMIC   GEOLOGY 


strongly  folded  Ordovician  slates  and 
sandstones  cut  by  a  batholith  of 
granite  or  quartz  monzonite.  At 
Bendigo  especially  the  ore  bodies 
show  saddles  along  the  axes  of  anti- 
clines, there  being  not  only  several 
lines  of  these  saddles,  but  in  each 
line  a  number,  one  below  the  other. 
Other  irregular  veins  occur.  The 
ore  is  gold-bearing  quartz,  with 
associated  pyrite  and  arsenopyrite, 
and  some  albite.  These  reefs,  as 
they  are  called,  have  been  worked  to 
a  depth  of  4500  feet,  but  are  much 
richer  in  the  first  2500  feet. 

At  Ballarat,  the  gold-quartz  veins 
show  more  irregularity  of  form,  and 
the  rich  ore  often  appears  to  be  at 
the  contact  of  flat  bodies  of  quartz 
with  thin  veins  of  pyrite,  or  carbo- 
naceous seams  in  the  slate,  both 
known  as  "indicators." 

Other  important  Australian  dis- 
tricts are  those  of  Charter  Towers, 
Queensland,  and  Hill  End,  New 
South  Wales. 

Queensland.  —  The  ore  body  at 
Mount  Morgan,  Queensland  *  is  to 
be  classed  as  one  of  the  interesting 
occurrences  of  the  world.  Worked 
for  many  years  as  a  gold  deposit, 
it  now  shows  signs  of  changing  to 
copper.  Below  a  rich  gossan  of 
limonite  and  manganese  carrying 
free  gold,  there  is  a  mass  of  porous, 
crumbly,  siliceous  rock,  carrying 
gold  and  some  silver,  which  is  in 
the  oxidized  zone.  Thi,s  at  depths 
of  200  to  300  feet  grades  into  a 
mixture  of  pyrite  and  chalcopyrite, 
carrying  gold.  While  several  theo- 
ries of  origin  have  been  advanced, 
it  can  probably  be  regarded  as 
a  replacement,  and  is  provis- 
ionally placed  in  the  intermediate 
group. 


1  Rickard,  Amer.  Inst.  Min.  Engrs.,  XX:    133,  1891;   Vogt,  Krusch  and   Bey- 
schlag,  Lagerstatten,  II:  134,  1912. 


GOLD   AND   SILVER 


707 


DETAIL  SECTION 

Showing  the  structure  of  quartz  crumple  and  "feeders"  at  east  face  of  drift 
on  Borden  lead,  from  actual  measurements  and  photographs,  10th  Sepl.  1903, 
by  E.R.  Faribault 


Scale  of  Feet 


FIG.  253.  —  Transverse  section  of  a  part  of  West  Lake  Mine,  Mount  Uniake, 
N.  S.     (After  Malcolm,  Can.  Geol.  Sum.,  Mem.  20-E.) 


708 


ECONOMIC   GEOLOGY 


£3 

\l 


Deposits  Formed  at  Shallow  Depths 

These  include  a  great  number  of  gold 
and  silver  deposits,  in  which  the  two 
metals  mentioned  are  present  in  varying 
proportions,  and  always  associated  with 
Tertiary  volcanics.  The  group  corre- 
sponds to  the  young  gold-silver  group  of 
Vogt,  Krusch,  and  Beyschlag.1 

The  wall  rocks  may  show  propyliti- 
zation,  silicification,  or  in  rarer  cases, 
alunitization.  Sericitization  is  also 
noted.  Quartz  is  the  commonest  gangue 
mineral,  but  carbonates  of  lime,  iron, 
or  manganese,  as  well  as  adularia  are 
noticed.  The  gold  may  be  native,  or 
combined  with  tellurium,  while  the  sil- 
ver is  usually  piesent  as  sulphides,  sulph- 
arsenides,  or  sulphantimonides. 

United  States.  —  As  stated  on  p.  684, 
the  ores  of  this  group  are  of  great  im- 
portance in  the  western  United  States. 

Goldfield,  Nevada  (88,  89).  —  Gold- 
field  lies  near  the  eastern  border  of 
Esmeralda  County  (Fig.  232),  on  the 
southern  rim  of  one  of  the  typical  des- 
ert basins  of  the  region  which  connects, 
through  a  low  pass  on  the  north,  with 
a  still  larger  basin  west  of  Tonopah. 

The  geologic  structure  (Fig.  254)  of 
the  district  is  quite  simple,  consisting 
essentially  of  a  low  dome-like  uplift  of 
Tertiary  lavas  and  lake  sediments,  rest- 
ing on  a  foundation  of  ancient  granitic 
and  metamorphic  rocks. 

The  kind  of  rocks  in  this  district, 
their  age,  and  relationships  are  shown  in 
the  map  and  section  given  by  Ransome 
(Figs.  255,  256).  The  oldest  or  Cam- 
brian beds  were  intruded  by  alaskite 


1  Lagerstatten,  II:  12,  1912. 


GOLD   AND   SILVER 


709 


at  about  the  close  of  Jurassic  time,  and  there  then  followed  a 
long  interval  of  erosion  before  the  eruption  of  the  Tertiary  lavas. 
It  will  be  seen  from  the  section  that  the  same  type  of  rock  was 
in  some  cases  erupted  more  than  once. 


Olivine  basalt, 
(Flows  and 

small  intru- 
Bions,) 


Rhyolite      Siebert        Quartz      Volcanic  Quartz  latite,  Dacite      Andesite     fthyolite    Andesite  Alaskite     Paleozoic 

(Later           tuffs,           basalt,       breccia   (Flowe  with    (Intru-  (Later  flows    (Earlier      (Earlier  (Intrusive    sediments 

flows;     (Lake  beds  (Flows  inter- (Roughly      same       give  masses)    and          flow  with        flows)  in 

including    oalated  in     bedded      rhyolite)                     intrusions)  intrusive  Paleozoic 

thin  flows      Siebert        local                                                           masses  and  sediments) 
ofrhyolite)      tuffs)        deposit)                                                             tuffs) 


FIG.  255.  —  Geologic,  Map  of  Goldfield,  Nev.,  district.    (After  Ransome,  Econ,  Geol.) 


The  ores  of  this  district,  which  are  of  somewhat  complex 
character,  consist  of  native  gold  and  pyrite  accompanied  by 
minerals  containing  copper,  silver,  antimony,  arsenic,  bismuth, 
tellurium,  and  other  elements. 

The  free  gold  occurs  in  some  of  the  ores,  in  fine  particles 
closely  crowded  together  and  forming  bands  or  blotches  in  the 


710 


ECONOMIC   GEOLOGY 


flinty  gangue,  and  is  not  likely  to  be  recognized  as  such  until 
examined  with  a  lens.  The  common  associated  minerals  are 
pyrite,  marcasite,  bismuthinite,  and  famatinite  (?).  At  times  the 
rich  ore  shows  a  curious  concentric  crustification,  consisting  of 


g  Malpais  basalt 

_o  Rabbit  Spring  formation 

ol  Spear  head  rhyolite 

Pozo  formation 


Siebert  formation 
Mira  basalt 

Siebert  formation 


Meda  rhyolite  and 

overlapping  andesite  breccia 

Dacite  vitrophyre 
Chispa  andesite 

Dacite  vitrophyre 


MilTtown  andesite 

and 
intrusive  dacite 


Sandstorm  rhyolite 
cut  by  dacite  and 
Morena  rhyolite 
Kendall  tuff 
cut  by  dacite 

Latite  cut  by  dacite 
and  Morena  rhyolite 

Vindicator  rhyolite 


Alaskite  and  granite 

intrusive  into 
Cambrian  shale 


mt&M 


Unc'f'y 
Unc'f'y 


Unc'fy 


Unc'f'y 


Long  erosion 
interval 


FIG.  256.  —  Generalized  columnar  section  of  geological  formations  at  Goldfield, 
Nev.     (After  Ransome,  U.  S.  Geol.  Surv.,  Prof.  Pap.  66.) 


fragments  of  silicified,  alunitized,  and  pyritized  rock,  covered 
with  shells  of  gold  and  sulphides. 

The  ore  bodies,  which  are  noted  for  their  remarkable  richness 
and  irregularity  (PI.  LXVII)  are  closely  related  to  fissures,  usually 
of  irregular  trend,  but  not  representing  fault  planes. 

The  deposits  (PL  LXVII)  are  denned  as  irregular  masses  of 
altered  and  mineralized  rock,  traversed  by  multitudes  of  small 
irregular,  intersecting  fractures,  such  fracturing  passing  in  many 
places  into  brecciation. 


712  ECONOMIC  GEOLOGY 

These  irregular  masses  are  termed  ledges  (Fig.  257),  and  within 
them  occur  the  actual  ore  bodies  or  pay  shoots.  Capping  these 
ledges  of  soft  rock  are  craggy  outcrops  (PL  LXVIII,  Fig.  2)  of 
silicified  and  alunitic  material  which  stand  out  in  relief  on  the 
surface  because  more  resistant  than  the  surrounding  rocks.  The 
ores  are  almost  invariably  associated  with  these,  but  every  sili- 
ceous knob  is  not  underlain  by  ore. 

The  most  important  ore  bodies  are  found  in  dacite,  but  some 
small  although  rich  ones  are  known  in  the  Milltown  andesite 
(Fig.  256). 


0  Myers  Mtn. 


FIG.  257.  —  Map  showing  outcrops  of  siliceous  ledges  east  of  Goldfield,  Nev. 
(After  Ransome,  U.  S.  GeoL  Surv.,  Prof.  Pap.  66.) 

The  alteration  of  the  rock  adjoining  the  fissures  is  of  three  types. 
Where  it  is  most  intense  the  rock  has  been  changed  to  porous,  fine- 
grained aggregates  consisting  essentially  of  quartz.  A  second  type 
is  the  change  to  a  soft,  light-colored  mass  of  quartz ;  while  a  third, 
which  is  of  propylitic  character,  consists  an  the  development  of 
calcite,  quartz,  chlorite,  epiddte,  and  gypsum. 

Most  of  the  ore  produced  during  the  first  two  or  three  years  of  the 
camp  was  oxidized  in  character,  but  now  some  of  the  mines  are 
working  in  sulphides. 

Origin.  —  Ransome's  theory  is  that  after  the  dacite  had  solidified, 
but  not  perhaps  entirely  cooled,  the  subjection  of  the  rocks  to 
stresses  of  unknown  origin  developed  a  complicated  system  of 
fractures. 

Hot  waters  carrying  hydrogen  sulphide  with  some  carbon  dioxide 
and  the  metallic  constituents  of  the  ores  rose  along  these  fissures ; 
oxidation  of  a  part  of  the  hydrogen  sulphide  to  sulphuric  acid 
occurred  in  the  upper  parts  of  the  fissure  zones  or  at  the  surface. 


PLATK  LXV1II 


FIG.  1.  —  Columbia  Mountain,  Goldfield,  Nev.,  from  the  south.     (H.  Ries,  photo.)} 


FIG.  2.  —  Ledge  outcrop  in  dacite  between  the  Blue  Bell  and  Commonwealth 
mines,  Goldfield,  Nev.  The  conspicuous  white  dump  is  alunitic  material. 
The  rough  knob  on  sky  line  near  right  side  of  view  is  Earner  Mountain. 
(After  Ransome,  U.  'S.  Geol.  Surv.,  Prof.  Pap.  66.) 

(713) 


714  ECONOMIC   GEOLOGY 

These  acid  solutions  then  percolated  downward  through  the 
shattered  rocks,  changing  their  feldspars  to  alunite,  mingled 
with  the  rising  solutions,  and  precipitated  most  of  their  metallic 
load  as  ore,  but  the  original  solutions  were  not  everywhere  rich 
in  metals. 

Following  this  the  ledges  were  fractured,  and  a  second  stage  of 
mineralization  occurred,  during  which  further  deposition  of  ore 
and  in  some  cases  repeated  precipitation  followed  more  fracturing. 

The  ledges  are  thought  to  have  been  formed  during  the  first  stage 
of  deposition,  and  the  softening  and  alunitization  of  the  rock,  as 
well  as  the  propylitization,  are  believed  to  have  occurred  at  the  same 
time.  Some  good  ore  was  also  deposited  then. 

The  Goldfield  mining  district  may  be  classed  as  one  of  the  newer  ones 
of  Nevada.  For  some  years  the  total  production  of  the  state  had  been 
small  but  the  discovery  of  Tonopah  in  1900  gave  a  new  impetus  to  the 
search  for  precious  metals  in  this  region,  and  the  finding  of  the  Goldfield 
deposits  may  be  rightly  reckoned  as  one  of  the  results. 

From  the  year  1904  to  the  end  of  1914  the  Goldfield  district  has  produced 
$71,311,552  in  gold,  833,442  ounces  of  silver,  and  3,139,780  pounds  of  copper. 
The  maximum  total  production  of  about  $11,000,000  was  reached  in  1910, 
since  which  time  it  has  dropped  off  to  about  $5,000,000.  The  bulk  of  the 
ore  is  cyanided. 

Tonopah,  Nevada  (83a^c,  90a,  91).  —  This  district,  which  was 
opened  up  in  1900,  has  grown  somewhat  steadily  in  production, 
so  that  its  maximum  yield  in  1913  was  about  $9,500,000. 1 
Tonopah  (PL  LXX,  Fig.  2)  lies  in  the  arid  desert  region  of  Ne- 
vada, and  the  rocks  consist  according  to  Spurr  of  a  somewhat 
complex  series  of  flows  and  intrusives  as  follows: 

8.  Basalts  and  rhyolites. 

7.  Siebert  tuffs. 

6.  Rhyolitic  flows. 

5.  Midway  andesite  flow. 

4.  West  end  rhyolite,  intrusive  just  above  3. 

3.  Montana  breccia,  a  trachy-alaskite  intrusion,  just  above  2. 

2.  Andesite  intrusion  between  la  and  16. 

1.  Trachyte  consisting  of:  a,  an  upper  part,  and  b,  a  lower 
flowbanded  glassy  part. 

Burgess  (83c),  differs  with  Spurr  in  considering  that  the  rocks 
are  all  surface  flows. 

1  The  1914  production  was  slightly  lower. 


GOLD  AND   SILVER 


715 


The  veins  belong  to  three  sets  or  periods  as  follows:  (1)  The 
chief  set,  formed  after  the  lower  trachyte,  and  before  the  andesite 
intrusion,  carrying  quartz  gold  and  silver;  (2)  formed  after  the 
West  end  rhyolite  and  before  the  Midway  andesite,  and  including 
four  subgroups,  viz.  a,  large  typically  barren  quartz  veins;  6, 
tungsten  bearing  veins;  c,  barren,  mixed  quartz  and  adularia 


Earlier  AndesiteR^f        Later  Ande 


Fraction  Dacite  Breccia  |o  o  o|     Oddie  Rhyolite  \~, 71 

olU,  DaciteLooJ  Broughef  Dacitel£<UU 


I  Tonopah  Rbyo 


300          COO  900          1200         1500 


TIG.  258.  —  Geologic  surface  map  of  the  producing  area  of  Tonopah.     (After 
Burgess,  Econ.  Geol,  IV:  683,  1909.) 

veins;  d,  productive  veins  like  those  of  set  1;  (3)  formed  after 
the  Tonopah  rhyolite,  and  carrying  quartz  with  occasional  lead, 
zinc  and  copper  sulphides. 

The  rocks  are  complexly  faulted,  and  the  movement  has 
occurred  at  different  periods.  The  primary  ore  consists  of  finely 
divided  native  gold,  argentite,  and  polybasite  in  a  gangue  of 
quartz  and  adularia.  In  the  oxidized  ore,  which  may  extend  to 
over  700  ft.,  cerargyrite,  embolite  and  iodyrite  are  found. 


716 


ECONOMIC  GEOLOGY 


I  I  I  I  I  § 


718 


ECONOMIC   GEOLOGY 


In  1914  the  total  average  recovery  value  per  ton  of  ore  pro- 
duced was  $16.84,  most  of  the  ore  being  treated  by  cyanidation 
with  and  without  concentration. 

Comstock  Lode,  Nevada  (83) .  —  This  lode,  of  historic  interest, 
occurs  near  Virginia  City,  in  southwestern  Nevada  (LXIII,  Fig. 
2),  and  is  a  great  fissure  vein  (Fig.  260),  about  4  miles  long,  several 
hundred  feet  broad,  and  branching  above,  following  approximately 


FIG.  260.  —  Section  of  Comstock  lode.    D,  diorite;  V,  vein  matter  in  earlier  dia- 
base  (/>&);  H,  earlier  hornblende  andesite;  A,  augite  andesite.     (After  Becker.) 

the  contact  between  eruptive  rocks,  and  dipping  at  an  angle  of  35 
to  45  degrees.  There  is  abundant  evidence  of  faulting,  which 
in  the  middle  portion  of  the  vein  has  amounted  to  3000  feet. 
The  lode  is  of  Tertiary  age,  and  contains  silver  and  gold  minerals 
in  a  quartzose  gangue. 

One  of  the  peculiar  features  of  the  deposit  is  the  extreme 
irregularity  of  the  ore,  which  occurs  in  great  "  bonanzas,"  some 
of  which  carried  several  thousand  dollars  to  the  ton.  The  fault- 
ing is  considered  to  have  been  quite  recent,  and  the  high  tem- 
peratures encountered  in  the  lower  levels  of  the  mine  indicate 
that  there  is  probably  a  partially  cooled  mass  of  igneous  rock 
at  no  great  depth. 

In  former  years  the  enormous  output  of  this  mine  caused  Nevada  to 
be  one  of  the  foremost  silver  producers.  It  was  discovered  as  early  as 
1858,  and  increased  until  1877,  after  which  it  declined.  Many  serious 
obstacles  were  met  with  in  the  development  of  the  mine,  such  that  it  has 
never  become  a  source  of  much  profit  in  spite  of  its  enormous  output.  In 
1863,  at  a  depth  of  3000  feet,  the  mine  was  flooded  by  water  of  a  temperature 


GOLD   AND   SILVER  719 

of  170°  F.,  due  to  a  break  in  the  clay  wall;  and  to  drain  it  $2,900,COO  were 
spent  in  the  construction  of  the  Sutro  tunnel,  which  was  nearly  four  miles 
long,  but  by  the  time  it  was  finished  the  workings  were  below  its  depth. 
A  second  difficulty  was  the  encountering  of  high  temperatures  in  lower 
workings,  those  in  the  drainage  tunnel  mentioned  being  110°  to  114°  F. 
The  lode  is  credited  with  a  total  production  of  over  $378,000,000.  In  recent 
years  its  output  has  been  slowly  increasing  again. 

Cripple  Creek  (63) .  —  This  district,  which  is  a  most  important 
one  of  this  type,  is  a  producer  of  ores  containing  gold  almost 
exclusively.  The  region  lies  about  ten  miles  west  of  Pike's  Peak 
proper,  but  in  the  foothills  of  this  mountain  mass. 


N.W. 

12,COO 

SECTION  C-C' 

vn.ni"  °°ne  - 

S.E. 

ll.COO  Copper  Mt. 

roneiWe  outline  o£ 

Big  Bull  lit. 

;       ' 

^Siiiigip^ 

, 

Vertical  and  horizontal  scale 

2 

8.s.w.  SECTION  D-D' 

12.000  ^c  ffone_    Bull  Cliff 


ll.COO    Straub  Jit.  .    nut1^eJ^-^°- """  '"~~-^  Trachyte  Mt. 


^??" 


Vertical  and  horizontal  scale 


FIG".  261.  —  Sections  showing  possible  outline  of  the  Cripple  Creek  volcanic  cone 
at  the  close  of  the  volcanic  epoch.  (After  Lindgren  and  Ransome,  U.  S.  Geol. 
Surv.,  Prof.  Pap.  54.) 

The  rocks  of  the  district  include  (1)  a  series  of  pre-Cambrian 
metamorphic  rocks  and  igneous  basement  complex,  and  (2)  the 
products  of  the  Tertiary  Cripple  Creek  volcano  (Fig.  261). 

The  metamorphic  rocks  include  a  quartz-muscovite-fibrolite 
schist,  and  a  biotite  gneiss ;  the  old  igneous  rocks  include  (1)  three 
varieties  of  granite,  viz.  the  Pikes  Peak  (quartz-biotite-microcline), 
Cripple  Creek  (finer-grained  but  similar),  Spring  Creek  (quartz- 
orthoclase  mainly,  and  of  medium  grain);  and  (2)  differentiation 
products  of  an  olivine-syenite  magma. 

The  Tertiary  volcanic  rocks  represent  a  series  of  chemically 
related  products,  from  a  single  eruptive  center.  Commonest  of 
these  are  tuffs  and  breccias,  which  are  cut  by  a  series  of  dikes  of 
phonolite,  next  a  latite-phonolite,  followed  by  a  syenite,  trachy- 
dolerite,  and  several  dark  basic  dike  rocks. 

The  ore  bodies,  which  in  nearly  all  cases  are  associated  with 
fissures,  are  of  two  types,  viz.  (1)  lodes  or  veins  (Figs.  262,  263), 


720 


ECONOMIC   GEOLOGY 


and  (2)  irregular^replacement  bodies,  occurring  usually  in  granite. 
The  two  are  not  sharply  separated. 

All  the  veins  are  characterized  by  the  narrowness  of  the  fissure 
and  incomplete  filling.  The  lode  fissures  occur  mainly  within  the 

volcanic  neck,  have  a  roughly  radial 
plan,  and  are  usually  nearly  vertical, 
the  individual  fissures  rarely  exceed- 
ing a  half  mile  in  length.  But  even 
the  productive  ones  may  be  quite 
short,  not  exceeding  a  few  hundred 
feet;  and  while  productive  lodes 
may  occur  in  all  rocks,  except  per- 
haps the  schist,  they  seem  to  favor 
the  breccia  and  granite,  many  fol- 
lowing phonolitic  or  basic  dikes. 

The  lodes  generally  show  a  char- 
acteristic sheeted  structure,  but  the 
fissures  in  general  are  not  fault 
planes,  having  probably  been  formed 
about  the  same  time  as  the  intru- 
sions of  the  basic  dikes  and  caused 
by  compressive  stresses  set  up  by  a 
slight  sinking  of  the  solidified  brec- 
cia and  associated  intrusives. 

The  ore  occurs  filling  narrow 
fissures,  and  within  the  veins  it  occurs  in  shoots  of  variable  size, 
which  may  develop  in  any  rock.  . 

The  ore  minerals  are  mainly  tellurides  of  gold,  deposited  chiefly 
by  fissure  filling  and  less  often  by  replacement,  with  pyrite  as  a 
common  associate;  but  native  gold  is  rare  in  the  unoxidized  ore. 
Quartz,  fluorite,  and  dolomite  are  the  most  important  gangue  min- 
erals, and  galena,  sphalerite,  tetrahedrite,  stibnite,  and  molybdenite 
are  found  sparingly. 

Oxidation  changes  the  vein  to  a  soft  brown,  homogeneous  mass, 
and  the  tellurides  into  brown,  spongy  gold  and  tellurites,  but  there 
is  no  evidence  of  secondary  enrichment.  The  ore  does  not  appear  to 
decrease  in  its  value  per  ton  with  depth,  though  the  actual  quantity 
of  it  is  less. 

The  rocks  bordering  the  veins  have  undergone  some  altera- 
tion, which  is  more  pronounced  in  the  breccia,  and  involves  a 
change  of  the  dark  silicates  to  carbonates,  pyrite,  and  fluorite, 


ORE  /LONG  5HEETEO  ZONE- 
FlG.  262. —  Section  of  vein  at  Cripple 
Creek,  Col.     (After  Rickard.) 


GOLD  AND   SILVER 


721 


and    of    the    feldspars   and  feldspathoids  to  sericite   and   adu- 
laria. 


0,900 


9,800- 


0,700- 


0,300- 


'&tf$£&.         : '  •  B R  F  cc i A 


0  100  200  300  FEET 

FIG.  263.  —  Vertical  section  through  the  Burns  shaft,  Portland  Mine,  Cripple 
Creek,  Col.  Shows  breccia,  contact  veins,  and  dikes.  V,  veins;  P,  phono- 
lite.  (After  Lindgren  and  Ransome,  U.  S.  Geol.  Surv.,  Prof.  Pap.  54.) 

The  ores  are  believed  to  have  been  deposited  by  hot  alka- 
line solutions,  which  contained  the  following  compounds  and 
ions  either  free  or  in  combination:  SiCb,  CC^,  H2S,  COs,  SO4, 
S,  Cl>  F,  Fe,  Sb,  Mo,  V,  W,  Te,  Au,  Ag,  Cu,  Zn,  Pb,  Ba,  Sr,  Ca, 


722 


ECONOMIC   GEOLOGY 


Mg,  Na,  K.     Some  of  these  may  have  been  leached  out  of  the 
volcanics. 

The  ore  is  in  part  smelting  ore,  which  is  sent  to  Fueblo  and 
Denver  for  treatment,  but  the  balance,  which  is  considerable,  is 
treated  by  the  cyanide  or  the  chlorination  process. 

The  Cripple  Creek  ores  as  a  rule  rim  low  in  silver  as  compared  with  gold, 
the  average  value  of  the  two  combined  being  about  $12.00  per  ton.  Over 
95  per  cent  of  the  crude  ore  is  treated  by  the  chlorination  or  cyanide 
process  at  mills  in  the  district  or  at  custom  mills  near  Colorado  City,  the 
rest  going  to  smelters. 

The  rapid  rise  of  this  district  is  well  shown  by  the  following  figures  of 
production.  A  maximum  was  reached  in  1900,  since  which  the  output 
has  gradually  declined. 

PRODUCTION  IN  CRIPPLE  CREEK  DISTRICT  IN  1893-1908  AND  1914 


YEAR 

VALUE 

YEAR 

VALUE 

1893       
1894 

$2,010,367 
2  908  702 

1902 
1903 

$16,912,783 
12  967  338 

1895       
1896 

6,879,137 
7  512  911 

1904       
1905 

14,504,350 
15  441  591 

1897       

10,139,708 

1906       

14,286,675 

1898 

13,507,244 

1907       

10,953,549 

1899       
1900 

15,658,254 
18,073,539 

1908       
1914       

12,772,477 
12,045,364 

17  261  579 

Total 

$203,835  568 

San  Juan  Region,  Colorado  (59,  62,  65,  66,  67).  — This  region  covers 
a  large  tract  of  mountainous  country,  in  southwestern  Colorado,  and 
includes  the  counties  of  San  Juan,  Dolores,  La  Plata,  Hinsdale,  and 
Ouray.  The  continental  divide  crosses  it,  but  the  main  portion 
consists  of  a  deeply  cut  volcanic  plateau.  The  area  is  an  important 
one  noted  for  its  veins  carrying  gold,  silver,  and  lead  ores  in  varying 
proportions,  but  owing  to  the  precipitous  slopes,  high  ridges,  and 
great  altitude  at  which  the  veins  outcrop,  mining  is  sometimes 
attended  with  difficulty.  Important  towns  in  the  area  are  Telluride, 
Silverton,  Ouray,  Creede,  etc. 

The  geological  history  of  the  San  Juan  region  is  exceedingly  com- 
plex, the  pre-Tertiary  surface  being  deeply  buried  under  volcanic 
beds  which  still  cover  the  main  area,  but  the  older  rocks  have  been 
exposed  by  erosion  in  the  surrounding  districts.  The  most  complete 
section  is  seen  in  the  Animas  Valley,  between  Silverton  and  Du- 
rango,  but  the  two  generalized  columnar  sections  of  the  Telluride 
and  Ouray  quadrangles  (PL  LXXI)  will  serve  to  give  a  somewhat 
clear  idea  of  the  age  and  succession  of  the  formations. 


PLATE  LXX 


FIG.  1.  —  View  of  Independence  Mine  and  Battle  Mountain,  Cripple  Creek,  Col. 
(A.  J.  Harlan,  photo.) 


FIG.  2.  —  General  view  of  region  around  Tonopah,  Nev.     (J.  E.  Spurr,  photo.) 

(723) 


ECONOMIC  GEOLOGY 


•5N 


i.'r--<i 
•I,-  ~v£ 


twr: 


•lo 


III? 


•5.-S 


*»       LL 

^   if 


KJ 


'•g  1  1 

O    £    +L 


•f!   * 


The  entire  region  has  not  been 
studied  in  detail  geologically,  but 
several  quadrangles  are  known  with 
some  intimacy  and  mayibe  referred  to. 

Telluride  Quadrangle  (65) .  • —  In  this 
quadrangle,  whose  geologic  section  is 
shown  (PL  LXXI  and'  'Fig.  264)  the 
ores  occur  in  veins  which  are  filled 
fissures  that  penetrate  all  rocks  ex- 
posed in  the  area,  and  were  later 
even  than  the  rhyolite  or  the  intru- 
sions of  the  diorite  stocks.  Four 
general  directions  of  fissuring  are 
noted. 

The  lodes  are  narrow  zones  of 
closely  spaced  fissures  filled  with 
ore,  little  of  which  is  found  outside 
of  the  zone.  The  veins  vary  in 
width,  averaging  about  3  feet,  but 
the  ore  usually  forms  a  narrow  strip 
following  one  side  or  the  other,  and 
rarely  filling  the  entire  zone. 

The  veins  also  vary  somewhat  in 
their  regularity,  according  to  the 
kind  of  rock  through  which  they 
pass,  being  best  developed  in  the 
andesite.  Faulting  is  rare. 

The  ore  minerals  are  galena,  frei- 
bergite  (argentiferous  gray  copper), 
polybasite,  proustite,  stephanite,  and 
perhaps  other  silver  sulphides,  with 
more  or  less  gold,  which  may  be  in 
pyrite  and  chalcopyrite.  There  are 
also  a  number  of  metallic  and  non- 
metallic  gangue  minerals,  including 
sphalerite,  zinc  blende,  mispickel, 
magnetite,  native  copper,  quartz,  cal- 
cite,  siderite,  rhodochrosite,  dolo- 
mite, fluorite,  barite  sericite,  biotite, 
chlorite,  amphibole,  apatite,  garnet, 
orthoclase,  picotite,  and  kaolinite. 


-+-4-  *f  7  +     -F4-4  4-  -*•  4 
44-   -44-  H-4  -J-  -r  -n-t 

VVA-VVV+W 

^V:^ 


Potosi  ^olcanics 
(2,000') 


•Silverton  series 
Andesites 
(230'-  2,500') 


San  Juan 
Andesite 
tuffs 
(3,000.0 


Shales  and* 
sandstones 
(  1,600'+ 


Sandstones 
and  shales 
(700'-  1,000') 


Permian 

sandstones   etc. 
(  2,000'+) 


Pennsylvanian 

sandstones 

shales  and 

limestones 
(  1,200'- 2,000') 

'l-lmetone(175') 


Quartzite  and 
slate 
(  8,000'+) 


+•  y-t  .  * 
'' 


--' 

V"  *  •  '*  "   ;  t  T<  *••  •  +";~^  ^  'i 

^^^t 

" 


^S'^V;^ 

.4  •1+%:4>'4(|+1  J-  V f.4>H,+* 

t*|^>S;&;/Sfe 


Potosi  rhyofite 
series  (1300'+) 


Intermediate 
1  series,  Andesite 
'  &  rhyoljte 
^  (1300') 


Saa  Juan  series, 
Andesite  debris 
12^00') 


San  Mjgu-el 
conglomerate 
(200'-  1,000*1 


Dolores 
sandstones 
conglomerates 
(1,550'+-) 


PLATE  LXXI  —  General  columnar  section  of  A,  Ouray  quadrangle;  B,  Telluride 
quadrangle.     U=  unconformity.     (U.  S.  Geol.  Surv.) 

(725) 


726 


ECONOMIC   GEOLOGY 


The  greater  number  of  veins  have  been  found  in  the  granular 
rocks  of  the  stocks  along  the  central,  east,  and  west  portions 
of  the  area,  and  in  the  heavy  andesitic  breccia,  tuff,  and  agglom- 
erate of  the  San  Juan  formation  (PL  LXXI),  best  developed 


Shales  and 
Sandstones 


FIG.  265.  —  Geologic  map  of  Telluride  district,   Col.,   showing  outcrop   of  more 
important  veins.     (After  Winslow,  Amer.  Inst.  Min.  Engrs,  Trans.  XXIX.) 

in  the  northern  half  of  the  area.  This  last  horizon  has  been  the 
most  productive. 

The  ore  appears  to  have  been  deposited  from  ascending  hot-water 
solutions  which  penetrated  all  open  spaces  in  the  fissured  zones. 

Ransome  explains  it  as  follows  :  Surface  waters  percolating  down- 
ward dissolve  alkalies  from  the  igneous  rocks  as  sulphides.  These 
alkalies  as  they  become  hotter  on  approaching  the  magma  become 
charged  with  sulphidic  and  carbonic  acids  derived  from  volcanic 


GOLD  AND  SILVER  727 

sources,  thus  becoming  solvents  for  the  metals,  and  silica,  lime, 
etc.,  which  they  gathered  from  the  more  basic  portions  of  the 
magma.  These  solutions  then  brought  metals  and  silicates  and 
deposited  them  higher  up. 

The  metals  were  deposited  in  the  fissures,  while  the  penetra- 
tion of  the  wall  rocks  by  the  alkaline  solutions  containing  sul- 
phuric acid  changed  the  iron  in  the  ferromagnesian  silicates, 
and  the  potash  went  toward  the  formation  of  sericite.  Carbon- 
ates were  deposited  on  the  walls,  due  to  the  action  of  water  on 
lime  feldspars.  Silica  was  set  free  and  removed  mostly  from 
the  walls.  Gold  was  carried  into  the  walls  to  some  extent. 

Silverton  Quadrangle  (67).  —  This  quadrangle  lies  east  of  the 
Telluride.  The  oldest  formations  are  the  Archaean  schists  and 
gneisses,  overlain  by  Algonkian  quartzites,  and  these  in  turn  by 
Cambrian,  Devonian,  and  Carboniferous  sediments,  the  whole 
being  capped  by  a  thick  series  of  Tertiary  volcanics  similar  to  those 
of  the  Telluride  quadrangle,  but  separated  from  the  top  of  the  Car- 
boniferous by  a  conglomerate.  A  number  of  unconformities  are 
present  in  different  parts  of  the  series. 

The  ore  deposits  are  of  three  types,  viz. :  (1)  lodes,  which  include 
most  of  the  now  productive  deposits;  (2)  stocks  or  masses,  which 
include  most  of  the  ore  bodies  formerly  worked  on  Red  Mountain; 
(3)  metasomatic  replacements,  including  a  few  deposits  found  in 
limestones  or  rhyolite. 

The  lodes,  which  are  widely  distributed  and  vary  in  size  and  de- 
gree of  mineralization,  may  occur  in  all  the  rocks  from  the  pre-Cam- 
brian  schists  to  the  latest  monzonitic  intrusions,  cutting  the  Ter- 
tiary volcanics,  but  the  greater  number  are  found  in  the  San  Juan 
tuff  and  Silverton  volcanic  series.  Moreover,  the  gold  and  silver 
are  not  uniformly  distributed  in  the  quadrangle. 

The  most  conspicuous  fissuring  is  northeast-southwest,  with  dips 
usually  of  about  75°,  and  faulting  noticeable  in  but  a  few  lodes. 
The  fissures  were  formed  substantially  at  the  same  time,  and  prob- 
ably in  late  Tertiary. 

Most  of  the  lodes  are  simple  fissure  veins,  showing  bands  of 
gangue  and  ore  confined  between  definite  walls,  while  the  width 
of  the  workable  vein  varies  from  a  few  inches  up  to  10  or  12  feet. 
The  wall  rock  is  not  usually  much  altered  except  in  the  rhyolite 
replacement  deposits. 

The  ore  minerals  are  tetrahedrite,  very  common,  may  carry  both 
As  and  Sb ;  enargite,  common  in  Red  Mountain  range ;  chalco- 


728  ECONOMIC  GEOLOGY 

pyrite,  common  and  sometimes  auriferous ;  galena,  very  important 
and  widespread ;  sphalerite,  common  and  accompanies  galena,  and 
several  silver  sulphides,  not  very  abundant.  Both  native  gold  and 
silver  also  occur. 

The  gangue  minerals  are  quartz,  barite,  calcite,  dolomite,  rho- 
dochrosite,  kaolinite,  pyrite,  etc. 

The  ores  were  probably  deposited  by  ascending  waters,  but  their 
exact  source  or  depth  of  origin  is  not  known. 

Metasomatism  of  wall  rocks  differs  in  different  parts  of  the  quad- 
rangle. Thus,  for  example,  in  the  Silver  Lake  Basin,  feldspar  is 
altered  to  sericite,  calcite,  and  quartz ;  augite,  to  calcite  and  chlorite; 
and  biotite,  to  sericite  and  rutile.  Sericite  and  quartz  are  common 
close  to  the  vein.  This  shows  a  propylitic  type  of  alteration. 

Ouray  Quadrangle  (62). — The  ore  deposits,  which  may  be  re- 
garded as  an  extension  of  those  of  the  Silverton  quadrangle  area,  are 
all  located  near  the  town  of  Ouray,  and  while  the  district  contains 
but  few  productive  mines,  they  are  of  great  scientific  interest.  A 
few  are  found  in  disturbed  rocks  near  dikes  or  sheets  of  porphyry, 
but  most  of  them  occur  in  but  slightly  disturbed  formations.  All 
owe  their  existence  to  the  presence  of  fissures,  the  form  of  the  ore 
body  depending,  however,  on  the  openness  of  the  fissure  and  kind 
of  wall  rock.  The  three  following  types  are  recognized  :  (1)  fissure 
veins  of  great  vertical  extent;  (2)  replacements  in  quartzite; 
.(3)  replacements  in  limestone.  Where  the  fissures  followed  by  the 
ore-bearing  solutions  were  open,  a  simple,  banded,  filled  vein  was 
formed;  but  where  narrow,  the  solutions  spread  out  laterally  in 
the  wall  rock,  replacing  the  same,  and  the  process  reached  a  maxi- 
mum in  the  more  soluble  beds. 

The  fissures  show  great  vertical  extent,  and  the  characters  of  the 
several  types  are  as  follows :  — 

Fissure  Veins.  —  (a)  This  type,  which  is  the  most  important, 
includes  silver-bearing  veins  in  fissures  of  slight  displacement, 
distributed  from  the  Mancos  shale,  to  the  sandstones  underlying 
the  McElmo  (PL  LXXI).  Ore  more  abundant  and  of  higher 
grade  in  quartzite  walls,  but  may  be  absent  or  of  low  grade  in 
shales.  Tetrahedrite  and  argentiferous  galena,  with  quartz  and 
barite  gangue  as  common  vein  minerals.  (6)  Gold-bearing  veins 
representing  a  group  of  mineralized,  highly  inclined,  sheeted 
zones  in  dikes  of  quartz-bearing  monzonite  porphyry.  The  chief 
minerals  are  auriferous  pyrite,  and  chalcopyrite  in  a  gangue  of 
country  rock  and  clay. 


GOLD  AND  SILVER  729 

Quartzite  Replacements.  —  Irregular  bodies  in  the  Dakota  sand- 
stones, with  gold  and  subordinate  silver. 

Limestone  Replacements.  —  Broad  flat  ore  bodies,  adjoining 
fissure  veins,  or  associated  with  numerous  small  vertical  fissures. 
Silver  predominates  in  some,  with  a  barite,  silica  gangue,  and  gold 
with  a  magnetite  gangue  in  others.  The  former  are  associated 
with  the  fissure  veins  which  penetrate  limestone. 

All  the  deposits  of  the  Ouray  district  appear  to  belong  to  a  single 
period  of  mineralization,  and  are  of  recent  formation,  being  later 
than  the  latest  igneous  intrusions. 

Other  Occurrences.  —  Among  the  other  occurrences  of  this  group 
may  be  mentioned  the  gold-quartz  veins  in  rhyolite  of  the  De 
Lamar  mine  in  Idaho  (72);  the  Bullfrog  district  of  Nevada  (87), 
and  the  National  mining  district  in  the  same  state  (85c).  At 
the  last  named,  the  fissures  in  Tertiary  lavas  carry  gold  and 
some  silver  in  a  quartz  gangue,  together  with  pyrite,  blende, 
and  always  more  or  less  stibnite,  while  one  contains  cinnabar. 
One  vein  had  a  remarkable  shoot  of  pale  gold  which  in  four  years 
yielded  nearly  $4,000,000. 

Another  interesting  occurrence  is  in  the  Republic  district  of 
Washington  whose  beautifully  crustified  quartz  veins  carry  both 
gold  and  selenium  (I19a),  the  only  other  deposit  of  this  type 
being  the  Redjang  Lebong  of  Sumatra.1 

Foreign  Deposits.  —  Hungary.  In  eastern  Hungary  2  including  Trans- 
sulvania,  there  are  a  number  of  gold  and  silver  deposits,  associated  with 
Tertiary  eruptives  chiefly  andesites  and  dacites.  Those  in  Hungary  include 
Nagybanya,  Felsobanya,  and  Kapnik,  and  in  Transylvania,  Brad  (the 
most  important),  Nagyag,  etc.  At  Nagyag  the  gold  occurs  as  tellurides, 
while  in  the  other  Transylvanian  districts,  it  is  native.  Accompanying  it 
are  silver-ore  minerals,  as  well  as  some  pyrite,  galena,  blende,  antimony, 
and  tetrahedrite,  in  a  gangue  chiefly  of  quartz,  but  often  containing  as  well 
manganese  carbonate  and  silicate.  The  veins,  which  may  be  a  meter  thick, 
are  usually  fissure  fillings,  and  the  lodes  may  be  30  to  60  feet  across.  Propy- 
litic  alteration  of  the  wall  rocks  is  common. 

New  Zealand.  —  The  veins  of  the  Hauraki  region  known  in  later 
years  for  the  output  of  the  famous  Waihi  mine,  contain  small  veins  of 
massive  or  comby  quartz  with  rich  pockets  of  gold  in  propylitized  Ter- 
tiary andesites  and  dacites  in  the  northern  part  of  the  district,  while  the 
southern  part  the  veins  are  of  great  width,  with  the  ore  shoots  uniform 
and  continuous.3 

1  Beck,  Erzlagerstatten,  I:  488;  Truscott,  Min.  Mag.,  VI:  355,  1912. 

2  Vogt,  Krusch  und  Beyschlag,  Lagerstatten,  II:  31,  1912. 

3  Finlayson,  Min.  Mag.,  II:  281,  1910;  also  Econ.  Geol.,  IV:  632,  1909. 


730  ECONOMIC   GEOLOGY 

Mexico  l  contains  a  number  of  well-known  representatives  of  this  group, 
located  especially  in  the  eastern  Sierra  Madre,  which,  though  usually  occurring 
in  Tertiary  eruptives,  sometimes  cut  sediments.  Among  these  localities 
should  be  mentioned  Parral,  Guanajuato,  Real  del  Monte,  Zacatecas,  and 
Pachuca.  Silver  predominates,  the  ore  minerals,  including  pyrargyrite, 
argentite,  stephanite,  and  polybasite,  accompanied  by  tetrahedrite,  galena, 
and  blende  in  a  gangue  chiefly  of  quartz.  The  greater  part  of  the  Mexican 
gold  production  comes  from  the  mines  of  El  Oro. 


Gold  Placers 

These  form  an  important  source  of  supply  of  gold,  together 
with  a  little  silver,  and,  although  widely  distributed,  become 
prominent  chiefly  in  those  areas  in  which  auriferous  quartz  veins 
are  abundant.  So,  while  in  North  America  they  are  found  in 
many  parts  of  the  Cordilleran  region,  the  Black  Hills,  and  south- 
ern Appalachian  region  of  the  United  States,  their  greatest 
development  is  in  the  Pacific  Coast  belt  from  California  to  Alaska, 
and  in  the  .Yukon  district  of  Canada.  Others  of  importance  are 
found  in  South  America  and  Australia. 

Most  of  the  gold  placers  are  of  Tertiary  or  Quaternary  age, 
but  older  ones  are  also  known  (p.  685) . 

Types  of  Placers.  —  Placer  deposits  may  be  formed  in  dif- 
ferent ways,  as  follows: 

Eluvial  placers.  —  These  originate  in  those  regions  where  gold- 
bearing  rocks  are  subjected  to  deep  weathering,  during  which  the 
gold  may  undergo  more  or  less  concentration,  and  also  migrate 
down  slope  to  some  extent.  The  gold  grains  are  usually  angular, 
as  they  have  not  been  exposed  to  the  wearing  action  of  streams. 
In  the  United  States,  this  type  is  known  in  the  southern  Appa- 
lachians, but  it  has  also  been  found  in  Brazil,  the  Guianas,  etc. 

Dry  cr  Eolian  placers  (36,  36a).  —  In  regions  of  aridity,  where 
the  rocks  are  disintegrated,  the  lighter  particles  may  be  blown 
away  while  the  heavier  ones,  including  gold,  remain  behind. 

Stream  placers  (42,  47) .  —  These  represent  the  most  important 
and  widespread  type.  As  the  products  of  rock  decay  are  washed 
down  the  slopes  into  streams,  the  fine  clayey  material  is  carried 
a  long  distance,  but  the  heavier  particles,  including  gold,  settle 
rapidly,  the  gold,  on  account  of  its  higher  gravity,  usually  col- 

1  Vogt,  Krusch  und  Beyschlag,  Lagerstatten,  II:  66,  1912.  Aguilera,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXXII:  497,  1902;  Ordonez,  Ibid.,  p.  224,  1902. 
(Pachuca);  Blake,  Ibid.,  p.  216,  1902.  (Guanajuato);  Bordeaux,  A.  F.  J.,  Ibid., 
XXXIX:  357,  1909.  (Silver  Mines.) 


GOLD  AND   SILVER  731 

lecting  in  the  lower  part  of  the  deposit,  or  even  in  crevices  of  the 
bed  rock.  Even  if  it  does  not  do  so  at  once,  agitation  of  the 
sediment  may  cause  it  to  settle  deeper,  or  even  slowly  migrate 
down  stream  as  the  sediment  shifts.  Coarse  gold  carried  down 
by  streams  from  higher  levels,  will  settle  with  coarse  sediment 
in  the  upper  part  of  a  stream's  course,  but  very  fine  flake  gold 
may  be  transported  some  distance  farther  down  stream. 

In  some  regions  thick  gold-bearing  gravel  deposits  have  by 
downward  cutting  of  the  streams  due  to  elevation  of  the  land, 
been  deeply  trenched,  leaving  the  uneroded  remnants  as  benches 
along  the  valley  slopes.  Cases  of  this  sort  are  found  on  the 
western  slope  of  the  Sierra  Nevada  in  California,  on  Anvil  Creek 
in  the  Nome  district  of  Alaska,  and  in  the  Klondike  district  of 
the  Yukon. 

In  some  instances  stream  placers  may  have  become  buried 
under  other  barren  gravels,  or  lava  flows.  (Victoria  and  some 
California  deposits.)  The  gold  in  such  instances  has  to  be 
recovered  by  underground  methods. 

Marine  placers.  —  These  are  formed  by  the  sorting  action  of 
the  waves  along  coasts  where  auriferous  gravels  or  sands  are 
exposed.  They  are  known  in  California  and  Oregon,  but  the 
best  examples  are  those  cf  Cape  Nome,  Alaska. 

Size  of  the  Placer  Gold.  —  Gold  occurs  in  placers  in  the  form 
of  nuggets,  flakes  or  dust-like  grains.  The  nuggets  represent  the 
largest  pieces,  and  the  finding  of  some  very  large  ones  has  been 
recorded  from  time  to  time  in  different  parts  of  the  world.  Two 
large  nuggets  are  recorded  from  Victoria:  one  the  "  Welcome 
Stranger,"  weighing  2280  ounces;  and  the  other  the  "  Welcome 
Nugget,"  weighing  2166  ounces.  Most  of  the  placer  gold  obtained 
is  in  small  grains,  and  some  may  be  very  fine.  Lindgren  states 
that  a  piece  of  gold  worth  one  cent  is  without  trouble  divisible 
into  2000  parts,  each  of  which  can  be  readily  recognized  in  a  pan. 

Associated  Minerals.  —  Placer  deposits  may  contain  a  num- 
ber of  heavy  minerals,  which  settle  out  with  the  gold  in  the  sluice 
boxes.  These  include  magnetite,  ilmenite,  (black  sand),  garnet, 
zircon  (white  sand),  monazite  (yellow  sand),  cassiterite,  and 
platinum.  Pyrite  or  marcasite  may  form  in  the  gravels. 

California  (42,  47). —  These  have  been  derived  from  the 
wearing  down  of  the  Sierras,  and  are  found  in  those  valleys  lead- 
ing off  the  drainage  from  the  mountains.  Many  were  formed 
during  the  Tertiary  period,  when  the  Sierras  were  subjected  to  a 


732 


ECONOMIC  GEOLOGY 


long-continued  denudation,  while  violent  volcanic  outbursts  at 
the  close  of  the  Tertiary  have  often  covered  the  gravels  and  pro- 
tected them  from  subsequent  erosion.  These  lava  cappings  are 
at  times  150  to  200  feet  thick,  as  in  Table  Mountain,  Tuolumne 
County. 

Many  of  the  gravel  deposits  are  on  lines  of  former  drainage,  while 
others  lie  in  channels  still  occupied  by  streams.     Some  show  but  one 

streak  of  gold,  while  in  others 
there  may  be  several,  some^f 
which  are  on  rock  benches  of 
the  valley  bottom  (Fig.  266). 

During  the  early  days  of  gold 
mining  in  California  the  gravels 
at  lower  levels  and  in  the  valley 
bottoms  were  worked,  but  as 
these  became  exhausted,  those 

FIG.     266.  —  Generalized    section   of    old 

placer,  with  technical   terms,     a,  vol-     farther    Up    the   slopes    Or    hills 
canic    cap ;   b,  upper   lead  ;   c,    bench     were  SOUght. 


gravel ;  d,  channel  gravel. 
Browne.) 


In  the  earlier  operations  the 
gravels  were  washed  entirely  by 
hand,  either  with  a  pan  or  rocker,  and  this  plan  is  even  now  followed 
by  small  miners  and  prospectors ;  but  mining  on  a  larger  scale  is 
carried  on  by  one  of  three  methods,  viz.  drift  mining,  hydraulic 
mining,  and  dredging. 

Drift  mining  is  employed  in  the  case  of  gravel  deposits  covered 
by  a  lava  cap,  a  tunnel  being  run  in  to  the  paying  portion  of  the 
bed  and  the  auriferous  gravel  carried  out  and  washed. 

In  hydraulic  mining  (PL  LXXII,  Fig.  1),  a  stream  is  directed 
against  the  bank  of  gravel  and  the  whole  washed  down  into  a 
rock  ditch  lined  with  tree  sections,  or  into  a  wooden  trough  with 
crosspieces  or  riffles  on  the  bottom.  The  gold,  being  heavy, 
settles  quickly  and  is  caught  in  the  troughs  or  ditches,  while  the 
other  materials  are  carried  off  and  discharged  into  some  neigh- 
boring stream.  Mercury  is  sometimes  put  behind  the  riffles  to 
aid  in  catching  the  gold. 

The  water  which  is  used  to  wash  down  the  gravel  deposits  is 
often  brought  a  long  distance,  sometimes  many  miles,  and  at 
great  expense,  bridging  valleys,  passing  through  tunnels,  and 
even  crossing  divides,  this  being  done  to  obtain  a  large  enough 
supply  as  well  as  a  sufficient  head  of  water. 

Owing  to  the  great  amount  of  debris  which  was  swept  down  into 


PLATE  LXXII 


FIG.   1.  —  Hydraulic  mining  of  auriferous  gravel.     The  sluice  box  in  foreground 
is  for  catching  the  gold. 


FIG.  2V —  An  Alaskan  placer  deposit. 


(733) 


734  ECONOMIC  GEOLOGY 

the  lowlands,  a  protest  was  raised  by  the  farmers  dwelling  there, 
who  claimed  that  their  farms  were  being  ruined  ;  and  it  soon  became 
a  question  which  should  survive,  the  farmer  or  the  miner,  for  in 
places  the  gravels  and  sand  from  the  washings  choked  up  streams 
and  accumulated  to  a  depth  of  70  or  80  feet.  The  question  was 
settled  in  1884  in  favor  of  the  farmer  by  an  injunction,  issued  by  the 
United  States  Circuit  Court,  which  caused  many  of  the  hydraulic 
mines  to  suspend  operations ;  and  at  a  later  date  this  was  extended 
by  state  legislation,  adverse  to  the  hydraulic  mining  industry. 
Owing  to  this  setback,  hydraulic  mining  fell  to  a  comparatively 
unimportant  place  in  the  gold-producing  industry  of  California, 
while  at  the  same  time  quartz  mining  increased. 

The  passage  of  the  Caminetti  law  now  permits  hydraulic  mining, 
but  requires  that  a  dam  shall  be  constructed  across  the  stream  to 
catch  the  tailings.  This  resulted  in  a  revival  of  the  industry,  but 
even  so,  the  placer  mining  industry  is  seriously  hindered  by  the 
present  laws  governing  it. 

Dredging  consists  in  taking  the  gravel  from  the  river  with  some 
form  of  dredge.     The  method,  which  was  first  practiced  in  New 
Zealand,  has  been  introduced  with  great  success  into   California, 
especially  on  the  Feather  River,  near  Oroville,  and  its  use  has  spread 
to  other  parts  of  the  Cordilleran  region  and  Alaska.     The  gravel 
when  taken   from  the  river  is  discharged   onto  a  screen,  which 
separates  the  coarse  stones,  and  the  finer  particles  pass  over  amal- 
gamated plates,  tables  with  riffles,  and  then  over  felt. 

Placer  gold  is  also  worked  in  Idaho,  Montana,  Oregon,  New 
Mexico,  and  Colorado,  all  of  the  deposits  except  those  of  the  last 
two  states  having  been  derived  mostly  from  Mesozoic  veins. 

Gold  also  occurs  in  beach  sand  of  certain  portions  of  the  Pacific 
coast  of  Washington  (119),  and  placer  mining  has  been  carried 
on  since  1894;  but  the  supply  of  gold,  which  is  obtained  from 
Pleistocene  sands  and  gravels,  is  small. 

In  arid  regions,  where  the  gold-bearing  sands  are  largely  the 
product  of  disintegration,  and  water  for  washing  out  the  metal  is 
wanting,  a  system  known  as  dry  blowing  is  sometimes  resorted  to. 

Alaska.  —  The  placer  deposits  have  been  found  in  many 
parts  of  Alaska,  but  the  two  regions  which  have  yielded  the 
largest  amount  are  the  Yukon  region  (24,  33)  and  the  Seward 
Peninsula  (24,  30),  the  latter  being  now  the  first. 

Gold  was  discovered  in  the  Forty  Mile  district  of  the  Yukon 
in  1886,  and  caused  a  stampede  for  this  region;  but  the  deposits 


GOLD  AND   SILVER  735 

of  the  Klondike  did  not  become  known  until  1896,  and  their  dis- 
covery was  followed  by  a  rush  of  gold  seekers  that  eclipsed  all 
previous  ones.  Indeed,  it  is  said  that  by  1898  over  40,000  people 
were  camped  out  in  the  vicinity  of  the  present  site  of  Dawson. 

The  Klondike  region  proper  is  situated  on  the  eastern  side  of 
the  Yukon  River,  and  the  richest  deposits  found  have  been  on 
the  Canadian  side  of  the  boundary.  The  gold  has  collected  either 
at  the  bottom  of  the  gravel  in  the  smaller  streams  tributary  to 
the  Yukon,  or  else  in  gravels  on  the  valley  sides,  this  latter  occur- 
rence being  known  as  bench  gravel.  The  metal  is  supposed  to 
have  been  derived  from  the  quartz  veins  found  in  the  Birch  Creek, 
Forty  Mile,  and  Rampart  series  of  metamorphic  rocks  lying  to 
the  east.  Up  to  the  end  of  1602  the  total  production  of  the 
Klondike  is  stated  to  have  been  $80,000,000.  The  annual  output 
has,  however,  decreased,  and  mining  in  that  region  has  settled 
down  to  a  more  permanent  basis.  Gravels  running  under  50 
cents  per  cubic  yard  cannot  be  worked  at  a  profit,  even  by 
dredging,  because  the  difficulties  and  expenses  of  mining  in  such 
a  region  are  great,  and  form  an  interesting  comparison  with 
conditions  in  California,  where  gravel  carrying  25  cents  per  yard 
is  considered  good,  while  that  running  as  low  as  5  cents  per  yard 
can  be  worked  as  a  dredge  proposition  (26). 1 

Since  the  discovery  of  the  rich  gold  gravels  on  the  Yukon, 
auriferous  gravels  have  been  developed  in  many  other  parts  of 
Alaska,  where  they  are  being  more  or  less  actively  worked  (Fig. 
241),  but  of  these  various  finds  those  in  the  Seward  Peninsula, 
which  is  now  the  largest  producer,  have  been  the  most  important. 

The  first  of  the  localities  discovered  in  the  last-mentioned 
region  was  Cape  Nome  (30,  31),  which  for  a  time  proved  to  be  a 
second  Klondike.  The  gold  was  discovered  here  on  Anvil  Creek, 
and  the  following  year  in  the  beach  sands  where  Nome  now  stands. 
These  discoveries  caused  another  northward  stampede,  which 
resulted  in  the  rapid  exhaustion  of  the  beach  sands;  but  other 
deposits  were  found  farther  inland  near  Nome,  as  well  as  the 
other  localities  on  the  Seward  Peninsula.  Some  quartz  veins  are 
also  worked.  Up  to  the  end  of  1914  the  Seward  Peninsula  had 
produced  $68,642,700  in  gold,  and  in  1906  its  production  is  given 
as  $7,500,000,  but  by  1914  it  had  dropped  to  $2,733,000.  In  the 
Fairbanks  district  (29),  which  is  another  important  placer  area, 
and  lies  in  central  Alaska  (Fig.  241),  there  is  a  remarkable  accu- 

1  See  also  U.  S.  Geol.  Surv.,  Bull.  263. 


736  ECONOMIC   GEOLOGY 

mulation  of  unconsolidated  material  overlying  the  bed  rock, 
which  seems  to  have  been  deposited  in  an  area  where  glaciation 
was  absent,  but  fluviatile  conditions  predominated. 

An  interesting  feature  of  these  deposits  is  their  remarkable 
thickness,  and  their  depth  of  consolidation  by  ice,  over  300  feet, 
as  revealed  by  mining  operations.  The  unconsolidated  material 
includes  slide  rock,  muck,  sand,  silt,  clay,  barren  gravels,  and  the 
gravels  in  which  the  gold  is  found.  These  productive  gravels, 
so  far  as  discovered,  are  a  thin  layer  next  to  bed  rock,  and  the 
value  of  the  gold  recovered  has  ranged  from  less  than  $1  to  $8  or 
more  per  square  foot  of  bed  rock  surface.  The  present  activities 
are  supported  by  low-grade  deposits  of  $1  or  less  per  square 
foot,  and  in  1914  deep  placers  yielding  as  little  as  40  cents  per 
square  foot  were  worked  by  drifting. 

The  Iditarod  district,  which  produced  about  $2,000,000  worth 
of  gold  in  1914,  obtained  mostly  by  dredging,  is  the  third  large 
producer. 

A  number  of  smaller  districts  add  to  the  total  supply  of  the 
territory. 

Yukon  Territory  (133).  — The  Klondike  gold  fields  are  situated 
on  the  east  side  of  the  Yukon  River  at  its  confluence  with  the 
Klondike,  and  cover  an  area  of  about  200  square  miles.  The  dis- 
trict IB  a  part  of  a  dissected  upland,  and  a  second  uplift  in  recent 
times  has  caused  the  streams  to  deepen  their  valleys,  but  portions 
of  the  old  valley  bottoms,  covered  with  heavy  accumulations  of 
gravel,  still  remain  as  benches  on  the  valley  sides  at  many  points. 
Owing  to  the  unglaciated  character  of  the  region,  the  rocks  are 
deeply  weathered.  The  surface  materials  are  permanently 
frozen. 

The  auriferous  gravels  occur  under  the  following  conditions: 
(1)  Low-level  creek  gravels,  4  to  10  feet  deep,  resting  on  bed 
rock,  and  covered  by  2  to  30  feet  more  of  black  frozen  muck. 
These  are  the  most  important;  (2)  gulch  gravels,  found  in  the 
upper  portions  of  the  main  creek  valleys,  and  small  tributary 
valleys;  (3)  gravels  on  rock  terraces,  formed  during  the  deepen- 
ing of  the  valleys,  and  representing  portions  of  an  old  valley 
bottom;  (4)  high-level  gravels,  representing  ancient  creek  de- 
posits, accumulated  when  the  river  flowed  several  hundred  feet 
higher  than  it  does  now.  Of  these  the  "  White  Channel  "  gravels, 
so  called  because  of  their  white  or  light-gray  color,  are  impor- 
tant, and  represent  the  oldest  stream  deposits  of  the  district. 


GOLD  AND   SILVER  737 

They  range  in  thickness  from  a  few  to  150  feet,  and  are  second 
in  commercial  importance  to  the  present  creek  gravels. 

The  Klondike  gold  varies  in  fineness,  due  to  its  being  in 
all  cases  alloyed  with  silver.  The  lowest  grade  has  a  value 
of  about  $12.50  an  ounce,  but  some  has  exceeded  $17.50  an 
ounce. 

Victoria.1  This  colony  contains  a  remarkable  series  of  buried  channels, 
called  "deep  leads."  The  gold  occurs  in  gravels  of  Tertiary  streams,  which, 
following  a  depression,  became  covered  by  thick  beds  of  sand  and  clay, 
and  these  in  turn  by  basalt  flows  of  several  hundred  feet  thickness.  The 
gold  was  first  discovered  in  the  upper  part  of  the  former  stream  courses 
and  then  followed  down  under  the  basalt. 

Russia.  —  Gold  gravels,  which  Purington  claims  belong  to  one  of  the 
greatest  placer  fields  of  the  world,  are  being  developed  on  the  Lena  River, 
in  Siberia.2 

South  Africa.3  The  auriferous  conglomerates  of  the  Johannesburg  dis- 
trict of  the  Transvaal,  S.  Afr.,  are  among  the  most  remarkable  known. 
They  are  of  apparently  simple  structure,  yet  very  puzzling  as  to  origin. 
The  section  involves  a  basal  series  of  crystalline  schists  intruded  by  granites, 
on  whose  eroded  surface  rests  the  Upper  and  Lower  Witwatersrand  system 
of  slates,  quartzites,  and  conglomerates,  aggregating  19,000  feet  in  thick- 
ness, and  overlain  in  turn  by  the  Ventersdorp  system  of  volcanics. 

The  Witwatersrand,  which  is  probably  of  Cambrian  or  pre-Cambrian  age, 
forms  a  syncline  with  Johannesburg  on  its  north  side.  The  series  has  been 
faulted  and  also  cut  by  diabase  dikes,  and  while  auriferous  conglomerates 
are  found  at  several  different  horizons,  the  most  productive  ones  are  in  the 
upper  part. 

The  ore  consists  of  pebbles  mostly  of  quartz,  in  a  sandy  matrix,  with 
abundant  pyrite  in  the  cement.  The  gold,  which  occurs  in  the  cement 
but  not  in  the  pebbles,  is  closely  connected  with  the  pyrite.  Some  of  the 
gold  has  migrated  and  recrystallized.  It  is  not  yet  definitely  settled  whether 
the  auriferous  conglomerate  represents  an  ancient  placer,  or  whether  the 
gold  and  pyrite  are  epigenetic  and  introduced  after  the  dikes,  and  for  the 
detailed  arguments  reference  should  be  made  to  the  articles  referred  to. 
It  is  provisionally  placed  with  the  placer  deposits. 

Uses  of  Gold.  —  Gold  is  chiefly  used  for  coinage,  ornaments, 
and  ornamental  utensils.  It  is  employed  to  a  considerable  extent 
in  dentistry  and  in  an  alloy  for  the  better  class  of  gilding. 

Its  value  for  use  in  the  arts  depends  on  its  brightness,  freedom 
from  tarnish,  and  its  ductility  and  malleability,  which  permit  it 

1  Lindgren,  Min.  Mag.  XI:  33,  1905,  and  Eng.  and  Min.  Jour.,  Feb.  16,  1905. 

2  Min.  Mag.  XII:  341,  1915. 

3  Hatch,  Types  of  Ore  Deposits,  San  Francisco,  1911;    Gregory,  Econ.  Geol., 
IV:    118,  1909;    Hatch,  Min.  and  Sci.    Pr.,  CIII:    98  and   132,  1911;    Horwood, 
Min.  and  Sci.  Pr.,  CVII:  563,  etc.,  1913;  Schwarz,  Min.  Mag.,  XIII:  223,  1915. 


738 


ECONOMIC   GEOLOGY 


to  be  easily  worked.  As  pure  24-carat  gold  is  too  soft  for  use, 
it  is  alloyed  with  a  small  amount  of  some  other  metal,  such  as 
copper,  to  gain  hardness. 

Uses  of  Silver.  —  This  metal  was  formerly  of  much  importance 
for  coinage,  but  is  much  less  so  now.  It  is,  however,  widely 
employed  in  the  arts  for  making  jewelry  and  utensils  such  as 
tableware.  Its  salts  are  of  more  or  less  value  in  medicine  and 
in  photography.  Its  brightness  and  white  color  are  valuable 
properties  when  the  metal  is  used,  but,  unlike  gold,  it  tarnishes 
somewhat  readily  when  exposed  to  sulphurous  gases.  There  are 
a  number  of  alloys  of  silver,  those  with  gold  and  copper,  respect- 
ively, being  of  importance. 

Production  of  Gold  and  Silver.  —  The  total  production  of 
gold  and  silver  for  the  United  States  and  other  countries  is  given 
on  the  following  pages. 

PRODUCTION  OF  GOLD  AND  SILVER  IN  THE  UNITED  STATES,  1860  TO  1914 


YEAR 

GOLD 

SILVER 

Ounces 

Value 

Ounces 

Commercial 
Value 

1880      .  .  .  . 

1,741,500 
1,678,612 
1,572,187 
1,451,250 
1,489,950 
1,538,373 
1,686,788 
1,603,049 
1,604,478 
1,594,775 
1,588,877 
1,604,840 
1,597,098 
1,739,323 
1,910,813 
2,254,760 
2,568,132 
2,774,935 
3,118,398 
3,437,210 
3,829,897 
3,805,500 
3,870,000 
3,560,000 
3,892,480 
4,265,742 
4,565,333 
4,374,827 
4,574,340 
4,821,701 
4,657,018 
4,687,053 
4,520,717 
4,299,783 
4,572,976 

$36,000,000 
34,700,000 
32,500,000 
30,000,000 
30,800,000 
31,801,000 
34,869,000 
33,136,000 
33,167,500 
32,967,000 
32,845,000 
33,175,000 
33,015,000 
35,955,000 
39,500,000 
46,610,000 
53,088,000 
57,363,000 
64,463,000 
71,053,400 
79,171,000 
78,666,700 
80,000,000 
73,591,700 
80,464,700 
88,180,700 
94,373,800 
90,435,700 
94,560,000 
99,673,400 
96,269,100 
96,890,000 
93,451,500 
88,884,400 
94,531,800 

30,318,700 
33,257,800 
36,196,900 
35,732,800 
37,743,800 
39.909,400 
39,694,000 
41,721,600 
45,792,700 
50,094,500 
54,516,300 
58,330,000 
63,500,000 
60,000,000 
49,500,000 
55,727,000 
58,834,800 
53,860,000 
54,438,000 
54,764,500 
57,647,000 
55,214,000 
55,500,000 
54,300,000 
57,682,800 
56,101,600 
56,517,900 
56,514,700 
52,440,800 
54,721,500 
57,137,900 
60,399,400 
63,766,800 
66,801,500 
72,455,100 

$34,717,000 
37,657,500 
41,105,900 
39,618,400 
41,921,300 
42,503,500 
39,482,400 
40,887,200 
43,045,100 
46,838,400 
57,242.100 
57,630,000 
55,662,500 
4o,800,000 
31,422,100 
36,445,500 
39,654,600 
32,316,000 
32,118,400 
32,858,700 
35,741,100 
33,128,400 
29,415,000 
29,322,000 
33,456,000 
34,222,000 
38,256,400 
37,299,700 
28,050,600 
28,455,200 
30,854,500 
32,615,700 
39,197,500 
40,348,100 
40,067,700 

1881  
1882 

1883  

1884 

1885  
1885           -  . 

1887  
1888  
1889  

1890  
1891  

1892    ... 
1893    ...     . 
1894    ... 
1895 

1896    ... 
1897    ... 
1898    ... 
1899    
1900    ... 
1901    ... 
1902           .  . 

1903  

1904  
1905  
1906  ...... 

1907    

1908  ...... 
1909  

1910         .   .  . 

1911 

1912  
1913 

1914  
Total  .   .  . 

102,852,715 

2,126,152,400 

1,831,133,800 

1,340,356,500 

GOLD  AND   SILVER 


739 


The  recovered  output  of  gold  and  silver  in  the  United  States 
from  domestic  ores  and  gravels  in  1914  is  given  below. 

APPROXIMATE  DISTRIBUTION,  BY  PRODUCING  STATES  AND  TERRITORIES,  OF 
THE  PRODUCTION  OF  GOLD  AND  SILVER  IN  THE  UNITED  STATES  FOR 
THE  CALENDAR  YEAR  1914,  IN  FINE  OUNCES  l 


STATE  OR  TERRITORY. 

GOLD 

SILVER 

Quantity 

Value 

Quantity 

Commercial 
Value 

Alabama  *./  . 

495 
800,471 
221,020 
1,028,061 
962,779 
813 
57,431 

10 

$         12,300 
16,547,200 
4,568,900 
21,251,900 
19,902,400 
16,800 
1,187,200 

200 

300 
865,900 
4,439,500 
2,020,800 
8,804,400 
100 
12,573,800 
1,900 
100 
415,500 
60,000 
12,536,700 
15,877,200 
1,771,300 
1,500 
6,200 
147,400 
10,300 

$            200 
478,800 
2,455,000 
1,117,500 
4,868,800 
100 
6,953,300 
1,200 
100 
229,800 
33,200 
6,932,800 
8,780,100 
979,500 
800 
3,400 
81,500 
5,700 

99,400 
56,800 
317,800 
6,482,300 
800 
188,700 
100 

California      
Colorado  
Georgia     
Idaho  
Illinois      

Maryland      
Michigan       
Mjssouri   
M  ontana  

Nevada     .      .      t:  -  .      ;  '  -  . 
New  Mexico       .     .     '     -  .     .     . 

North  Carolina       .       -  '  .     .     .    • 

200,446 
558,064 
58,974 
6,303 

4,143,600 
11,536,200 
1,219,100 
130,300 

Oklahoma      .      .      .           ... 
Oregon      ....           ... 
Philippine  Islands  .           ... 
Porto  Rico    .  '  .'.-,  .           .     .     .'   : 
South  Carolina        .           .     .     * 
South  Dakota    .     .           ....   % 
Tennessee      ...           ... 
Texas 

76,887 
53,179 
135 
155 
354,782 
309 
426 
163,362 
15 
28,435 
324 

1,589,400 
1,099,300 
2,800 
3,200 
7,334,000 
6,400 
8,800 
3,377,000 
300 
587,800 
6,700 

179,800 
102,800 
574,700 
11,722,000 
1,500 
341,300 
100 

Urah    ... 
Virginia    ....           ... 
Washington  ...           ... 
Wyoming       ...            ... 

Total  .     .     .     .     .... 

4,572,976 

94,531,800 

72,455,100 

40,067,700 

1  Gold  value,  $20.67+  per  fine  ounce.  Average  commercial  price  of  silver  in  1914, 
55.3  cents  per  fine  ounce. 

The  totals  for  this  table  are  based  on  bullion  deposits  in  the  United 
States  mints  and  a^say  offices  and  statements  from  the  smelting  and  refin- 
ing establishments.  The  table  is  derived  from  three  sources:  (1)  the  un- 
refined domestic  gold  and  silver  deposited  in  the  United  States  mints  and 
assay  offices;  (2)  the  domestic  gold  and  silver  in  fine  bars  reported  by  the 
private  refineries;  (3)  the  unrefined  gold  and  silver  contained  in  ores  and  matte 
exported  for  reduction.  The  last  is  an  item  of  small  relative  importance. 
In  addition,  the  domestic  smelters  and  refineries  produced  as  refined  bullion 
from  foreign  ore,  matte,  and  unrefined  bullion,  875,250  fine  ounces  of  gold, 
and  39,789,129  fine  ounces  of  silver.  Of  the  foreign  gold  there  is  credited 
to  Mexico,  199,652  ounces;  to  Canada  (including  British  Columbia,  the 
Yukon,  and  the  Klondike),  532,572  ounces;  to  Central  America,  61,123 
ounces;  to  South  America,  45,161  ounces;  to  Cuba,  320  ounces;  and  to  all 
other  foreign  sources,  36,420  ounces.  Of  foreign  silver  there  is  credited 
to  Mexico,  19,643,774  fine  ounces;  to  Canada,  7,084.354  ounces;  to  Central 
America,  2,458,094  ounces;  to  South  America,  5,432,676  ounces;  to  Cuba, 
51,542  ounces;  and  to  all  other  foreign  sources,  5,118,689  ounces. 


740 


ECONOMIC    GEOLOGY 


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742 


ECONOMIC   GEOLOGY 


PERCENTAGE  OF  OUTPUT  OF  GOLD  AND  SILVER  BY  PROCESSES  IN  THE  UNITED 
STATES  IN  1912,  1913,  AND  1914 


PRODUCTION  BY 

PERCENTAGE  OF  TOTAL  OUTPUT 

Gold 

Silver 

1912 

1913 

1914 

1912 

1913 

1914 

Placers    

Gold  and  silver  mills: 
By  amalgamation 
By  cyanidation      ... 
By  chlorination 

Total  milling       .     . 
Smelting  1   .                      . 

24.8 

24.9 

25.3 

0.2 

0.2 

0.2 

22.3 

30.9 
.4 

21.5 
31.2 
.3 

20.9 
31.4 
.2 

1.2 
17.8 

.6 
19.7 

.4 
22.1 

53.6 

53.0 

52.5 

19.0 

20.3 

22.5 

21.6 

22.1 

22.2 

80.8 

79.5 

77.3 

Total  2       ..... 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

1  Both  crude  ore  and  concentrates. 

2  Philippine  Islands  and  Porto  Rico  excluded. 

AVERAGE  EXTRACTION  VALUS  OF  GOLD  AND  SILVER  PER  TON  IN  1914,  BY 
STATES  AND  TERRITORIES 


STATE  OR  TERRITORY. 

DRY  OR 
SILICEOUS 
ORES 

COPPER 
ORES 

LEAD 
ORES 

ZINC 
ORES 

COPPER- 
LEAD  AND 

COPPER- 

LEAD- 
ZINC  ORES 

LEAD- 
ZINC 
ORES 

Alabama  and  Georgia 
Alaska  . 

$2.46 
2  80 

$2   14 









Arizona      
California  . 

8.46 
5  53 

.33 
1  84 

11.92 
16  99 

$2.86 

$4.08 

$2.53 

Colorado    ..... 
Idaho    
Maryland  and  Virginia  1 
Michigan  l 
Montana   
Nevada      
New  Mexico  .... 
North  Carolina  2     .     . 
Oklahoma       .... 
Oregon       
South  Carolina  . 
South  Dakota     .     .     . 
Tennessee  2     . 
Texas 

10.25 

8.85 
20.00 

9.37 
11.39 
10.11 
7.17 
18.00 
8.99 
.92 
3.68 

7  09 

13.38 
1.66 
.84 
.20 
1.14 
.39 
.20 
14.90 

.09 
16  34 

7.66 
3.42 

8.62 
13.13 
6.20 

32.98 
35  .  57 

.004 
.34 

3.05 
3.90 

43.11 

18.17 
12.77 
11.45 

1.72 
2.91 

3.40 
3.96 

2  21 

Utah     
Washington    .... 

Wisconsin  l     . 
Wyoming  .      .      .     .     . 

7.38 
8.66 

9.22 

.39 
2.51 
.27 
.56 

7.91 
10.41 



18.76 

2.75 

Total  average    . 
Per  cent  of  tonnage 

6.95 
25.46 

.49 
64.26 

5.29 
5.36 

.19 
1.44 

12.87 
.02 

2.90 
3.46 

1  Includes  only  copper  ore  yielding  precious  metals. 
1  Lead  and  zinc  ores  yielded  no  precious  metals. 

Gold  and  Silver  Reserves.  —  Lindgren  has  pointed  out  (13)  that  the 
gold  reserves  of  the  United  States  are  large,  but  that  it  is  difficult  to 
estimate  them  with  any  degree  of  exactness,  a  rough  estimate  even  being 


GOLD  AND   SILVER 


743 


possible  only  in  the  case  of  placers,  which  are  found  chiefly  in  California 
and  Alaska.  These  are  estimated  to  contain  perhaps  $1,000,000,000  of 
gold  in  reserve,  and  the  output  from  this  source  will  probably  not  decrease 
for  some  time.  The  gold  derived  from  copper  ores  is  not  large 
($4,800,000  in  1908),  but  is  a  stable  and  increasing  quantity,  likely  to 
last  for  25  years  at  least.  That  derived  from  lead  ores  is  much  less,  and 
a  slow  decrease  may  be  expected. 

The  quartzose  ores  form  an  important  source,  likely  to  continue  active 
and  strong  producers.  The  United  States  gold  production  is  not  likely 
to  rise  above  $110,000,000,  nor  is  it  likely  to  sink  below  $60,000,000  for 
a  long  time.  Owing  to  the  low  price  of  silver,  a  number  of  mines  produc- 
ing ore  of  this  metal  have  shut  down,  but  the  increasing  amount  supplied 
as  a  by-product  from  lead  and  copper  ores  has  kept  the  output  steady. 
The  present  supply  is  regarded  as  assured  as  long  as  the  mining  of  lead 
and  copper  ores,  as  well  as  quartzose  gold  ores,  continues  on  the  present 
scale. 

PRODUCTION  OF  GOLD  AND  SILVER  IN  CANADA  BY  PROVINCES  IN  1914 


PROVINCE 

GOLD 

SILVER 

Ounces. 

(fine) 

Value 

Ounces 

Value 

British  Columbia  .      . 
Yukon      ..... 
Nova  Scotia 
Ontario    

252,730 
247,940 
2.C04 
268,264 
1,292 
48 

$5,224,393 
5,125,374 
60,031 
5,545,509 
26,708 
992 

3,159,897 
92,973 

25,139,214 
57,737 

$1,731,971 
50,959 

13,779,055 
31,646 

Alberta     
Total       ... 

773,178 

15,983,007 

28,449,821 

15,593,631 

PRODUCTION  OF  GOLD  AND  SILVER  IN  CANADA 


YEAR 

GOLD 

SILVER 

Ounces 

Value 

Ounces 

Value 

1858    
1860    
1865    
1870    

34,104 
107,806 
192,898 
83,415 
97,729 
63,121 
55,575 
55,620 
1  100.798 
2  1,350,057 
684,951 
493,707 
773,178 

$    705,000 
2,228,543 
3,987,562 
1,724,348 
2,020,233 
1,304,824 
1,148,829 
1,149,776 
2,083,674 
27,908,153 
14,159.195 
10,205,835 
15,983,007 

— 

$      419,118 
1,030,299 
2,740,362 
3,621,133 
17,580,455 
15,593,630 

1876    
1880    
1885    .      .      .      .     -. 
1890    
1895    
1900    
1905    
1910    
1914    



400,687 
1,578,275 
4,468,225 
6,000,023 
3  32,869,264 
28,449,821 

1  Yukon  output  began  about  this  time. 

2  Decreased   from   here    until    1907,    then   remained   stationary,    until    Porcupine   dis- 
covery increased  it  again. 

3  The  maximum  production  was  19,440,165  ounces  in  1912. 


744 


ECONOMIC   GEOLOGY 


PRODUCTION  OF  GOLD  IN  THE  WORLD,  1860-1914 

[The  annual  production  from  1860  to  1872  is  obtained  from  5-year  periods 
compiled  by  Dr.  Adolph  Soetbeer.  From  1872  to  1912,  inclusive,  the  esti- 
mates are  those  of  the  Bureau  of  the  Mint.  The  figures  for  1913  and  1914 
are  in  part  final  and  in  part  estimates  of  the  Survey  from  best  available 
information,  and  are  subject  to  revision.] 


YEAR   VALUE 


YEAR    VALUE 


YEAR    VALUE 


YEAR     VALUE 


1860 
1861 
1862 
1863 
1864 
1865 
1866 
1867 
1868 
1869 
1870 
1871 
1872 
1873 
1874 


$134,083,000 
122,989,000 
122,989,000 
122,989,000 
122,989,000 
122,989,000 
129,614,000 
129,614,000 
129,614,000 
129,614,000 
129,614,000 
115,577,000 
115,577,000 
96,200,000 
90,750,000 


1875 
1876 
1877 
1878 
1879 
1880 
1881 
1882 
1883 
1884 
1885 
1886 
1887 
1888 
1889 


$  97,500,000 
103,700,000 
113,947,200 
119,092,800 
108,778,800 
106,436,800 
103,023,100 
101,996,600 
95,392,000 
101,729,600 
108,435,600 
106,163,900 
105,774,900 
110,196,900 
123,489,200 


1890 
1891 
1892 
1893 
1894 
1895 
1896 
1897 
1898 
1899 
1900 
1901 
1902 
1903 
1904 


$118,848,700 
130,650,000 
146,651,500 
157,494,800 
181,175,600 
198,763,600 
202,251,600 
236,083,700 
286,879,700 
306,724,100 
254,576,300 
260,992,900 
296,737,600 
327,702,700 
347,377,200 


1905 
1906 
1907 
1908 
1909 
1910 
1911 
1912 
1913 
1914 

Total 


$380,288,700 
402,503,000 
412,966,600 
442,476,900 
454,059,100 
455,239,100 
461,939,700 
466,136,100 
454,942,211 
453,000,000 


$11,257,320,811 


GOLD  PRODUCTION  IN  THE  WORLD  IN  1913  AND  1914  BY  COUNTRIES 


COUNTRY 


1913 


1914 


North  America: 

United  States  .      . 

Canada    .... 

Mexico    .... 

Cuba 

Africa 

Australasia 
Europe: 

Russia  and  Finland 

Austria-Hungary  . 

Germany 

Norway  .... 

Sweden    .... 

Italy 

Spain  and  Portugal 

Turkey    .... 

France     .... 

Great  Britain    . 

Servia       .... 
South  America: 

Argentina     . 

Bolivia  and  Chile 

Colombia 

Ecuador  .... 

Brazil       .... 

Venezuela     . 

Guiana: 

British  .  .  . 
Dutch  .  .  . 
French 

Peru 

Uruguay 

Central  America  . 
Asia: 

Japan       .... 

China       .... 

Indo-China  .     . 

Chosen  (Korea)     . 

Siam 

India,  British    . 

East  Indies,  British 

East  Indies,  Dutch 

Total 


i  $88,884,400 

1  16,216,131 

2  18,250,000 

3  24,600 

4  205,875,000 

i  53,038,090 

e  24.578,575 
«  2480,414 

3  60,000 

*  36,630 

4  30,572 
e  2,500 

6500 

s  1,946,600 

i  17,860 

3  250,000 

3  100,000 

3  800,000 
3  3,000,000 

7289,133 
*  3,009,786 

«  444,800 

«  1,353,368 
«  470,433 

8  3,050,600 
»  492,200 
8111,000 

3  3,000,000 

i  4,470,723 

s  3,658,900 

3  70,000 

4  3,281,333 

s  56,500 

is  11,152,463 

8  1,352,000 

83,387,100 


454,942,211 


1  $94,531,800 
i  15,925,044 
3  18,000,000 

3  201,000,000 
M9,386,180 

3  26,750,000 
3  1,500,000 


1,000,000 
100,000 


3  500,000 
3  3,000,000 


3  3,000,000 


3  1,250,000 
»  500,000 

3  3,000,000 
3  500,000 

33,500,000 

9  4,476,500 
3  3,800,000 

»  3,750,000 

8  11,388,870 
4,750,000 


10  453,000,000 


i  Official;  2  Min.  World,  Feb.  6,  1915;  3  estimated;  «  Director  Mint.  Ann.  Rep., 
1914;  5  Min.  Mag.,  Apr.,  1915;  •  Min.  Mag.,  1914;  i  Min.  Jour.,  Dec.  5,  1914;  8  Min. 
Indus.,  1914;  »  Min.  and  Sci.  Pr.,  May,  8,  1915;  ">  includes  estimates  for  countries  not 
specified. 


GOLD  AND   SILVER  745 

REFERENCES  ON  GOLD  AND  SILVER 

GENERAL.  1.  Blake,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVI:  290,  1897. 
(Gold  in  igneous  rocks.)  la.  Brokaw,  Jour.  Geol.,  XVIII:  321,  1910. 
(Solution  of  gold  in  weathering.)  2.  Crane,  Gold  and  Silver,  New 
York,  1908.  3.  Cumenge  and  Robellaz,  L'Or  dans  la  Nature,  Paris, 
1898.  4.  Curie,  The  Gold  Mines  of  the  World,  London,  1902.  5.  De 
Launay,  The  World's  Gold,  Its  Geology,  Extraction,  and  Political 
Economy,  Translation,  New  York,  1908.  6.  Don,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XXVII:  564,  1898.  (Genesis  of  certain  auriferous 
lodes.)  7.  Emmons,  W.  H.,  Amer.  Inst.  Min.  Engrs.,  Trans.  ^XLII: 
3,  1912.  (RePn  of  manganese  to  gold  sec'y  enrich't.)  8.  Kemp,  Min. 
Indus.,  VI:  295,  1898.  (Telluride  ores.)  9.  Keyes,  Econ.  Geol., 
Dec.  1607.  (Cerargyritic  ores.)  10.  Lenher,  Econ.  Geol.,  IV:  544, 
1909.  (Tellurides.)  11.  Lenher,  Econ.  Geol.,  VII:  744,  1912.  (Trans- 
p'n  and  depos'n  of  gold  in  nature.)  12.  Lincoln,  Econ.  Geol.,  VI: 
247,  1911.  (Certain  natural  associations  of  gold.)  13.  Lindgren, 
U.  S.  Geol.  Surv.,  Bull.  394,  1909.  (Conservation  of  gold,  silver,  re- 
sources.) 13a.  Lindgren,  Amer.  Inst.  Min.  Engrs.,  Bull.  112:  721, 
1916.  (Gold  and  silver  of  N.  Amer.  and  S.  Amer.)  14.  MacLaren, 
Gold,  Its  Geological  Occurrence  and  Geographical  Distribution,  London, 
1909.  15.  Merrill,  Amer.  Jour.  Sci.,  I:  309,  1896.  (Gold  in  granite.) 
15a.  Palmer  and  Bastin,  Econ.  Geol.",  VIII:  140,  1913.  (Metallic 
minerals  as  precipitants  of  gold  and  silver.)  16.  Rickard,  Min.  and 
Sci.  Pr.,  LXXVII:  81  and  105,  1898.  (Minerals  accompanying  gold.) 
17.  Rickard,  Min.  and  Sci.  Pr.,  Oct.  20,  1906.  (Geological  distribution 
of  world's  gold.)  17a.  Sharwood,  Econ.  Geol.,  VI:  22,  1911.  (Tel- 
lurium bearing  gold  ores.)  18.  Spurr,  Eng.  and  Min.  Jour.,  LXXVI: 
500,  1903.  (Gold  in  diorite.)  19.  Spurr,  Ibid.,  LXXVII:  198,  1904. 
(Native  gold  in  original  metamorphic  gneisses.)  20.  Stokes,  Econ. 
Geol.,  I:  644,  1906.  (Experiments  on  solution  and  transportation  of 
gold  and  silver.)  21.  Weed,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXX: 
424,  1901.  (Enrich't,  gold  and  silver  veins.) 

AREAL.  —  Alabama:  22.  Brewer,  Ala.  Geol.  Surv.,  Bull.  5,  1896.  23. 
Phillips,  Ala.  Geol.  Surv.,  Bull.  3,  1892.  —  Alaska:  24.  Brooks  and 
others,  U.  S.  Geol.  Surv.,  Bull.  259:  1905,  also  later  ones  issued  annually, 
descriptive  of  Alaska  resources.  25.  Moffat,  U.  S.  Geol.  Surv.,  Bull.  314: 
126.  (Nome  region.)  26.  Penrose,  Eng.  and  Min.  Jour.,  LXXVI:  807, 
852,  1903.  (General.)  27.  Prindle,  U.  S.  Geol.  Surv.,  Bull.  375,  1909. 
(Forty  Mile  region.)  28.  Prindle,  U.  S.  Geol.  Surv.,  Bull.  345:  179. 
(Yukon-Tanana  region.)  29.  Prindle  and  Katz.  U.  S.  Geol.  Surv., 
Bull.  379:  181,  1909.  (Fairbanks  placers.)  30.  Schrader  and  Brooks, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XXX:  236,  1901.  (Cape  Nome.) 

31.  Smith,  U.  S.  Geol.  Surv.,  Bull.  379,  1909.     (Nome  and  vicinity.) 

32.  Spencer,  U.  S.  Geol.   Surv.,   Bull.  287,   1906.     (Juneau  district.) 

33.  Spurr,  U.  S.  Geol.  Surv.,  18th  Ann.  Rept.,  Ill:   101,  1898.     (Yukon 
district.)  — Arizona:   34.  Bancroft,   U.  S.  Geol.  Surv.,  Bull.  451,  1911. 

•  (N.  Yuma  County.)  35.  Blandy,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XI:  286,  1883.  (Prescott  district.)  36.  Carter,  Min.  and  Sci.  Pr., 
CV:  166,  1912.  (Placers.)  36a.  Heikes  and  Yale,  U.  S.  Geol.  Surv.. 


746  ECONOMIC   GEOLOGY 

Min.  Res.,   1912,   I:    255,   1913.     (Dry  placers.)     37.  Kellogg,  Econ. 
Geol.,   I:     651,   1906.     (Cochise  County.)     38.  Schrader,  U.  S.  Geol. 
Surv.,  Bull.  397,  1909.     (Cerbat  Range,  Black  Mts.,  Grand  Wash  Cliffs.) 
39.  Schrader,  U.  S.  Geol.  Surv.,  Bull.  582:   92,  1915.     (Santa  Rita  and 
Patagonia  Mts.)     39a.  Jones,  U.  S.  Geol.  Surv.,  Bull.  620:    45,  1915. 
(Quartzite.)  —  California:      40.  Bateson,    Amer.     Inst.     Min.    Engrs., 
Trans.  XXXVII:    160,   1907.     (Mojave  district.)     41.  Brown,  Amer. 
Inst.    Min.    Engrs.,    Trans.    XXXVIII:     343,    1908.     (Vein    systems, 
Bodie,  Calif.)     42.  Browne,  Calif.  State  Min.  Bur.,  10th  Ann.  Rept.: 
435.     (River  gravels.)     43.  Diller,  U.  S.  Geol.  Surv.,  Bull.  353,  1908. 
(Taylorsville  region.)     44.  Diller,   U.   S.   Geol.   Surv.,   Bull.   260:    45, 
1905.     (Indian  Valley  region.)     45.  Fairbanks,  Calif.  State  Min.  Bur., 
X:    23,    1890,   and  XIII:    665,   1896.     (Mother  Lode  district.)     45a. 
Hess,   U.   S.   Geol.   Surv.,   Bull.  430:    23,    1910.     (Randsburg  quad.) 
46.  Hill,  U.  S.  Geol.    Surv.,  Bull.  594,  1915.     (N.  Calif.)     47.  Lind- 
gren,   U.   S.   Geol.   Surv.,   Prof.   Pap.   73,    1911.     (Auriferous   gravels, 
Sierra  Nevada.)      48.  Lindgren,  U.  S.  Geol.  Surv.,  17th  Ann.  Rept.,  II: 
1,  1896.     (Nevada  City  and  Grass  Valley.)     49.  Lindgren,  Geol.  Soc. 
Amer.,    Bull.    VI:     221,    1895.     (Gold   Quartz   veins.)     50.  Lindgren, 
U.  S.   Geol.   Surv.,    14th  Ann.   Rept.,   II:    243,   1894.     (Ophir.)     51. 
Ferguson,  U.  S.  Geol.  Surv.,  Bull.  580.    (Alleghany  mining  district.)     52. 
Ransome,  U.  S.  Geol.  Surv.,  Geol.  Atlas,  No.  63,  1900.     (Mother  Lode 
district.)     53.  Turner,    Amer.     Geol.    XV:     371,     1895.     (Auriferous 
gravels.)  — Colorado:    54.  Bastin  and  Hill,  U.  S.  Geol.  Surv.,  Bull. 
620,   1916.     (Gilpin  Co.)     54a.  Crawford,   Col.   Geol.   Surv.,   Bull.   4, 
1913.     (Monarch  dist.)     55.  Emmons,  Eng.  and  Min.  Jour.,  XXXV: 
332,  1883.     (Summit  district.)     56.  Emmons,  U.  S.  Geol.  Surv.,  17th 
Ann.  Rept.,  II:    405,  1896.     (Custer  Co.)     57.  Emmons  and  Larsen, 
U.  S.  Geol.  Surv.,  Bull.  530,  1913.     (Creede.)     58.  George  and  Craw- 
ford, Col.  Geol.  Surv.,   1st  Rept.:    189,   1909.     (Hahn's  Peak  field.) 
59.  Cross  and  Spencer,  U.  S.  Geol.  Surv.,  Atl.  Fol.  60.     (La  Plata 
quadrangle.)     60.  Hill,  U.  S.  Geol.  Surv.,  Bull.  380:    21,   1909.     (S. 
E.  Gunnison  County.)     60a.  Hills,  Col.  Sci.  Soc.,  Proc.  I:    20,  1883. 
(Summit.)     6C6.  Hunter,    U.   S.   Geol.    Surv.,    Bull.    580:    25,    1914. 
(Custer  Co.)     61.  Irving  and  Bancroft,  U.  S.  Geol.  Surv.,  Bull.  478, 
1911.     (Lake  City.)     62.  Irving,  U.  S.  Geol.  Surv.,  Atl.  Fol.  153,  1907. 
(Ouray.)     63.  Lindgren  and  Ransome,  U.  S.  Geol.  Surv.,  Prof.  Pap. 
54,    1906.     (Cripple  Creek.)     63a.  Means,   Econ.   Geol.   X:     1,    1915. 
(Red    Cliff.)     64.  Patton,    Col.    Geol.    Surv.,    1st   Rept.:     105,    1909. 
(Montezuma    district.)     64a.  Patton    and    others,    Col.    Geol.    Surv., 
Bull.  3,    1912.     (Park  Co.)     65.  Purington,  U.  S.   Geol.   Surv.,   18th 
Ann.  Rept.,  Ill:    751,  1898.     (Telluride.)     66.  Ransome,  U.  S.  Geol. 
Surv.,  22d  Ann.  Rept.,  II:    231,   1902.     (Rico  Mts.)     67.  Ransome, 
U.  S.  Geol.  Surv.,  Bull.   182,   1901.     (Silverton.)     67a.  Ransome,  U. 
S.  Geol.  Surv.,  Prof.  Pap.  75,  1911.     (Breckenridge  dist.)     68.  Spurr 
and  Garrey,  U.  S.  Geol.  Surv.,  Prof.  Pap.  63,  1908.     (Georgetown  dis- 
trict.) —  Georgia:    69.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  213:    57,  1903, 
(Dahlonega    district.)     70.  Lindgren,    U.    S.    Geol.    Surv.,    Bull.    293. 
(Dahlonega.)     71.  McCallie,  Ga.  Geol.  Surv.,  Bull.  19,  1909. —  Idaho: 


GOLD  AND   SILVER  747 

72.  Lindgren,  U.  S.  Geol.  Surv.,  20th  Ann.  Kept.,  Ill:  75,  1900.     (Silver 
City,   De  Lamar  Co.)      73.  Lindgren,   U.   S.   Geol.   Surv.,   18th  Ann. 
Kept.,  Ill:  625,1898.     (Idaho  Basin  and  Boise  Ridge.)     73a.  Umpleby, 
U.  S.  Geol.  Surv.,  Bull.  528,  1913.     (Lemhi  Co.)  —Kansas:   74.  Lind- 
gren, Eng.  and  Min.  Jour.,  LXXIV:    111,  1902.     (Tests  for  gold  and 
silver  in  shales.)  —  Maryland:   75.  Weed,  U.  S.  Geol.  Surv.,  Bull.  260: 
128,   1905.     (Great  Falls.)  —  Michigan:    76.  Wadsworth,  Ann.  Rept., 
1892,  Mich.  State  Geologist.  —  Minnesota:    77.  Winchell  and  Grant, 
Minn.  Geol.  and  Nat.  Hist.  Surv.,  XXIII:    36,  1895.     (Rainy  Lake 
district.) —  Montana:     78.  Emmons,    U.    S.    Geol.    Surv.,    Bull.    340: 
96,    1908.     (Little   Rocky   Mountains.)     78a.  Emmons,    W.    H.   Ibid., 
Bull.  315:  45,  1907.     (Cable  Mine.)     79.  Lindgren,  U.  S.  Geol.  Surv., 
Bull.  213:    66,  1903.     (Bitter  Root  and  Clearwater  Mts.)     80.  Weed, 
U.  S.  Geol.   Surv.,  Bull.  213:   88,  1903.     (Marysville.)     81.  Weed   and 
Barrell,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  II:    399,  1902.     (Elkhorn 
district.)     82.  Weed  and  Pirsson,  U.  S.  Geol.  Surv.,  18th  Ann.  Rept., 
Ill:    589,    1898.     (Judith   Mts.) — Nevada:     82a.  Barnes   and   Byler, 
Min.  and  Sci.  Pr.,  July  12,  1913.     (Faulting  and  mineralization,  Gold- 
field.)    83.  Becker,  U.  S.  Geol.  Surv.,  Mon.  Ill,  1882.     (Comstock  Lode.) 
83a.  Eakle,  Univ.  Calif.,  Dept.  Geol.,  Bull.  VII:    No.  1,  1912.     (Ton- 
opah   minerals.)     836.  Burgess,    Econ.    Geol.,   VI:     13,    1911.     (Silver 
halogens,  etc.,  Tonopah.)     83c.  Burgess,  Econ.  Geol.,  IV:    681,  1909. 
(Tonopah.)     84.  Emmons,  U.  S.  Geol.  Surv.,  Bull.  408,  1910.     (Elko, 
Lander,  and  Eureka  counties.)     85.  Garrey  and  Emmons,  U.  S.  Geol. 
Surv.,   Bull.   303.     (Manhattan.)     85a.  Hill,   U.   S.   Geol.   Surv.,   Bull. 
540:    223,   1914.     (Yellow  Pine  dist.)     856.  Hill,   U.  S.  Geol.   Surv., 
Bull.  594:   51,  1915.     (N.  W.  Nev.)     85c.  Lindgren,  U.  S.  Geol.  Surv., 
Bull.  601,  1915.     (National  dist.)     S5d.  Locke,  Econ.  Geol.  VII:    583, 
1912.     (Temperatures,  Comstock  Lode.)     86.  Lord,  U.  S.  Geol.  Surv., 
Mon.    IV,    1883.     (Comstock    mining.)     87.  Ransome,    Emmons,    and 
Garrey,  U.  S.  Geol.  Surv.,  Bull.  407,  1910.     (Bullfrog.)     87a.  Ransome, 
U.  S.  Geol.  Surv.,  Br.U.  414,   1909.     (Humboldt  Co.)     88.  Ransome, 
U.  S.  Geol.  Surv.,  Prof.  Pap.  66,  1909;   also  Econ.  Geol.,  V:   301,  438, 
1910.     (Goldfield.)     89.  Ransome,   Econ.   Geol.,  II:    667,  1907.     (Alu- 
lite  in  Goldfield  district.)     89a.  Schrader,  U.  S.  Geol.  Surv'.,  Bull.  497: 
162,1912.      (Jarbridge,  Contact,  and  Elk  Mountain  dist.)  896.     Schra- 
der, U.  S.  Geol.  Surv.,  Bull.  580:    325,  1914.     (Rochester  dist.)     90. 
Spurr,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXVI:   372,  1906.     (Genetic 
relations   western   Nevada  ores.)     90a.  Spurr,   Econ.   Geol.,   X:    713, 
1915.     (Tonopah.)     91.  Spurr,  U.  S.  Geol.  Surv.,  Prof.  Pap.  42,  1905. 
(Tonopah.)     92.  Spurr,  U.  S.  Geol.  Surv.,  Prof.  Pap.  55,  1906.     (Silver 
P2ak  quadrangle.)     93.  Young,   Eng.   and   Min.   Jour.,   XCIII:     167, 
1912.     (Comstock  Lode,  conditions  on.) — New  England:    94.  Smith, 
U.  S.  Geol.  Surv.,  Bull.  225:    81,  1904.     (Me.  and  Vt.)     95.  Graton, 
U.  S.  Geol.  Surv.,  293.  —  North  Carolina:    96.  Laney,  N.  Ca.  Geol. 
Surv.,   Bull.   21,    1910.     (Gold  Hill  district.)     97.  Nitze  and  Hanna, 
N.  Ca.  Geol.  Surv.,  Bulls.  3  and  10.  —  New  Mexico:    98.  Anderson, 
Eng.    and   Min.   Jour.,    LXIV:    276,    1897.     (Mogollon   Range.)     99. 
Keyes,  Amer.  Inst.  Min.  Engrs.,  Trans.,  XXXIX:    139,  1909.     (Lake 


748  ECONOMIC   GEOLOGY 

Valley.)  100.  Lindgren  and  Graton,  and  Gordon,  U.  S.  Geol.  Surv., 
Prof.  Pap.  68,  1910.  (General.)  lOOa.  Paige,  U.  S.  Geol.  Surv., 
Bull.  470:  109,  1911.  (Pinos  Altos  dist.)  —  Oklahoma:  101.  Bain,  U.  S. 
Geol.  Surv.,  Bull.  225:  120,  1904.  (Wichita  Mts.)  —  Oregon:  102. 
Diller,  U.  S.  Geol.  Surv.,  20th  Ann.  Kept.,  Ill:  7,  1900.  (Bohemia 
district.)  102o.  Grant  and  Cady,  Min.  Res.  Ore.,  I,  No.  6:  131,  1914. 
(Baker  dist.)  l03.  Kimball,  Eng.  and  Min.  Jour.,  LXXIII:  889, 
1902.  (Bohemia  district.)  104.  Lindgren,  U.  S.  Geol.  Surv.,  22d  Ann. 
Kept.,  II:  551,  1901.  (Blue  Mts.)  105.  Pardee  and  Hewitt,  Min. 
Res.  Ore.,  I,  No.  6,  1914.  (Sumpter  quad.)  105a.  Swartley,  Min. 
Res.  Ore.  I,  No.  8,  1914.  (N.  E.  Ore.)  —  South  Carolina:  106.  Graton, 
U.  S.  Geol.  Surv.,  Bull.  293,  1909.  107.  Thies  and  Mezger,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XIX:  595,  1891.  (Haile  Mine.)  See  also 
No.  113.  —  South  Dakota:  108.  Carpenter,  Amer.  Inst.  Min.  Engrs., 
Trans.  XVII:  570,  1889.  109.  Irving,  U.  S.  Geol.  Surv.,  Bull.  225: 
123,  1904,  and  U.  S.  Geol.  Surv.,  Prof.  Pap.  26,  1904.  (N.  Black  Hills.) 
110.  O'Harra,  S.  Dak.  Geol.  Surv.,  Bull.  3,  1902.  (Black  Hills.)  111. 
Smith,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVI:  485,  1897.  (Cambrian 
ores.)  — Texas:  Ilia.  Dumble,  Amer.  Inst.  Min.  Engrs.,  Trans.  XLIV: 
588, 1913.  (Eocene  placers.)  1116.  Phillips,  Eng.  and  Min.  Jour.,  Dec. 
31,  1910.  (Shafter  dist.)  112.  Udden,  Tex.  Univ.  Min.  Surv.,  Bull. 
8:  54,  1904.  (Shafter  dist.)  —  United  States:  113.  Lindgren,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXXIII:  790,  1903.  (N.  Amei.  production 
and  geology.)  114.  Nitze  and  Wilkens,  Amer.  Inst.  Min.  Engrs., 
Trans.  XXV:  661,  1896.  (Appalachians.)  —  Utah:  115.  Emmons, 
Amer.  Inst.  Min.  Engrs.,  XXXI:  658,  1902.  (Horn  silver  and  Delamar 
mines.)  116.  Hill,  Col.  Sci.  Soc.,  Proc.  V:  54,  1898.  (Camp  Floyd 
district.)  117.  Spurr,  U.  S.  Geol.  Surv.,  16th  Ann.  Rept.,  II:  343, 
1895.  (Mercur.)  Also  references  under  Silver-Lead.  118.  Warren, 
Eng.  and  Min.  Jour.,  LXVII1:  455,  1899.  (Daly-West  Mine.)  —  Ver- 
mont: See  New  England.  — Virginia;  118a.  Watson,  Mineral  Resources 
of  Virginia,  1907;  Taber,  Bull.  7,  Va.  Geol.  Survey,  1913.  —  Washington: 
119.  Arnold,  U.  S.  Geol.  Surv..  Bull  2<50:  154,  1905.  (Beach  placers.) 
119o.  Lindgren  and  Bancroft,  U.  S.  Geo!.,  Bull.  550,  1914.  (N.  E. 
Wash  and  Republic  dist.)  120.  Smith,  Eng.  and  Min.  Jour.,  LXXIII: 
379,  1902.  (Mt.  Baker  district.)  12L  Smith.  U.  S.  Geol.  Surv.,  Bull. 
213:  76,  1903.  (Central  Washington.)  122.  Spurr,  U.  S.  Geol.  Surv., 
22d  Ann.  Rept,,  II:  777,  1901.  (Monte  Cristo.)  122a.  Weaver, 
Wash.  Geol.  Surv.,  Bull.  6,  1911.  (Blewett  dist.)  —  Wyoming:  123. 
Beeler,  Min.  Wld.,  Dec.  26,  1908,  (South  Pass  district.)  124.  Knight, 
Wyo.  Univ.  Sch.  of  M.  Bull.,  1901.  (Sweet water  district,  Fremont 
County.)  125.  Schultz,  U.  S.  Geol.  Surv.,  Bull.  315.  (Cent.  Uinta 
County.) 

Canada:  —  126.  Burrows,  Ont.  Bur.  Mines,  XIX,  Pt.  3:  164,  1913.  (Gow- 
ganda.)  127.  Burrows,  IUd.,  XXIV,  Pt.  3,  1915.  (Porcupine.)  128. 
Burrows  and  Hopkins,  IUd.,  XXIII:  301,  1914.  (Kirkland  Lake  and 
Swastika.)  129.  Cairnes,  Can.  Geol.  Surv.,  Rep.  1911:  33,  1912. 
(Quartz  mining,  Klondike.)  130.  Cairnes,  Ibid.,  Mem.  31,  1912. 
(Wheaton  dist.,  Yukon.)  131.  Cairnes,  Ibid.,  Mem.  37,  1913.  (Atlin 


GOLD   AND   SILVER  749 

dist.,  B.  C.)  132.  Cairnes,  Can.  Min.  Jour.,  XXXII:  215,  1911. 
(Tellurium  ores.)  133.  Cairnes,  Internat.  Geol.  Congr.,  Can.,  1913, 
Guide  Book  10:  95.  (Klondike.)  134.  Camsell,  Can.  Geol.  Surv., 
Mem.  26,  1913.  (Tulameen.)  135.  Camsell,  Ibid.,  Mem.  2,  1910. 
(Medley,  B.  C.)  136.  Cole,  Annual  Repts.  T.  and  N.  O.  Ry.  (Cobalt, 
etc.)  137.  Coleman,  Ont.  Bur.  Mines,  Bull.  1,  1897.  (W.  Ont.) 

138.  Dresser,    Can.    Geol.    Surv.,    Bull.    1028,    1908.     (L.    Megantic.) 

139.  Keele,  Can.  Geol.  Surv.,  Summ.  Rept.,  1911:   303,  1912.     (Meule 
Cr.,  Que.)     140.  Malcolm,  Ibid.,  Mem.  20.     (N.  S.)     141.  McConnell, 
Ibid.,  Bull.  979,  1907.     (Klondike  high  level  gravels.)     142.  McConnell, 
Ibid.,  Summ.  Rept.,  1910:  59,  1911.     (Portland  Canal.)     143.  McLean, 
Can.    Dept.   Mines,    Mines   Branch,   Bull.   222,    1914.     (Lode  mining, 
Yukon.)     144.  Miller,  for  references  on  Cobalt,  Ont.,  see  under  Nickel 
and  Cobalt.     145.  Parsons,  Ont.  Bur.  Mines,  XXI,  Pt.  1:    169,  1912. 
(Lake  of  Woods,   Manitou,   Dryden.)     146.  Rickard,   Inst.   Min.  and 
Met.,  London,    Trans.   XXI:    506,    1912.     (N.  S.)     147.  Wilson,  Can. 
Geol.  Surv.,  Mem.  17,  1912.     (Larder  Lake,  Ont.)     Many    scattered 
references  in  reports  of  Ontario  Bureau  of  Mines,  Canadian   Geological 
Survey,  and  Minister  of  Mines  for  British  Columbia.     See  also  references 
under  Lead-Silver. 


CHAPTER  XX 
MINOR   METALS 

ALUMINUM  —  MANGANESE  —  MERCURY 
ALUMINUM 

Ores.  —  This  is  one  of  the  few  metals  whose  ores  do  not  present 
a  metallic  appearance.  Many  different  minerals  contain  aluminum, 
but  it  can  be  profitably  extracted  from  only  a  few.  Common  clay, 
for  example,  presents  an  inexhaustible  supply,  but  the  chemical 
combination  of  the  aluminum  in  it  is  such  that  its  extraction  up  to 
the  present  time  has  not  been  found  commercially  practicable, 
although  a  number  of  processes  with  this  end  in  view  have  been 
patented. 

The  minerals  which  might  serve  as  sources  of  aluminum, 
together  with  the  percentage  of  metal  they  contain  are :  Corundum, 
A12O3  (53.3  per  cent);  cryolite,  3NaF-AlF3  (12.8  per  cent); 
diaspore,  A^Os,  HbO  (45.1  per  cent);  bauxite,  A^C^H^O 
(39.13  per  cent);  gibbsite,  A12033H2O  (34.6  per  cent). 

Of  these,  corundum  is  too  valuable  as  an  abrasive,  and  is  not 
found  in  sufficient  quantity  to  permit  its  use  as  an  ore  of  alumi- 
num. Until  the  discovery  of  bauxite,  cryolite,  (see  p.  332)  was 
the  chief  source  of  the  metal,  all  of  it  being  obtained  from  Green- 
land. 

While  aluminum  ore  is  usually  referred  to  as  bauxite,  it  seems 
doubtful  whether  this  is  the  only  one  of  the  aluminum  hydrates 
present,  and  there  is  no  doubt  that  gibbsite  may  also  occur.  It 
is  known  in  the  Arkansas  deposits,  and  Watson  (16)  believes  it 
also  to  be  present  in  the  Georgia  ones. 

Bauxite  derives  its  name  from  Baux  in  southern  France,  where 
it  was  first  discovered,  but  in  recent  years  large  deposits  have  been 
found  in  the  United  States.  It  is  usually  pisolitic  in  structure, 
and  may  sometimes  resemble  clay  in  appearance.  The  com- 

753 


MINOR   METALS 


751 


mon  impurities  are  silica,  iron  oxide,  and  titanic  acid;  and  the 
variation  in  the  amount  of  these  ingredients  can  be  seen 
from  the  following  analyses  of  both  domestic  and  foreign 
occurrences. 


ANALYSES  OF  BAUXITE 


1 

2 

3 

4 

5 

6 

7 

8 

Alumina  (AlaOs) 

57.60 

61.89 

63.16 

59.22 

61.00 

62.05 

62.46   39.92 

Ferric  oxide  (FeaOs) 

25.30 

1.96 

23.55 

3.16 

2.20 

1.66 

.81 

16.84 

Silica  (SiOa)    .     .     . 

2.80 

6.01 

4.15 

3.30 

2.10 

2.00 

4.72 

20.00 

Lime         carbonate 

(CaCOs)     .     .     . 

.40 

— 

— 

— 

— 

— 





Titanic  acid  (TiO2) 

3.10 

— 

— 

3.62 





.23 

1.47 

Water  (H2O)      .     . 

10.80 

27.82 

8.34 

28.80 

31.58 

30.31 

31.03 

19.52 

Moisture  .... 

— 

— 

— 

1.90 

3.12 

3.50 

1.25 

Alkalies 

(Na2O,  K2O)  .     . 

— 

— 

.79 

— 

— 

— 

— 

— 

1.  Baux,  France.  2.  Glenravel,  Ireland.  3.  Wochein,  Germany.  4. 
Georgia.  5.  Rock  Run,  Alabama.  6.  Arkansas.  7  and  8.  Wilkinson 
County,  Georgia. 

It  should  be  stated  that  all  of  these,  except  Nos.  3  and  8,  represent  good 
grades  of  ore,  but  that  within  any  one  district,  or  even  in  the  same  deposit, 
there  may  be  considerable  variation  in  composition. 

It  is  indeed  probable  that  some  highly  aluminous  fire  clays  and 
kaolins  may  contain  aluminum  hydroxides,  and  Galpin  (5),  has 
identified  gibbsite  (hydrargillite)  in  those  from  Olive  Hill,  Ken- 
tucky, etc.  Aluminum  hydroxides  also  occur  abundantly  in 
laterites,  (9,  10,  17)  but  these  are  too  impure  to  be  used  as  ores 
of  aluminum. 

Distribution  of  Bauxite  in  the  United  States.  —  Bauxite  in  com- 
mercial quantity  is  known  to  occur  in  but  six  districts  in  the 
United  States.  These  are  the  Georgia-Alabama  district,  the 
Arkansas  district,  Wilkinson  County,  Georgia,  near  Chatta- 
nooga, and  Keenburg,  Tennessee,  and  a  small  area  in  southwestern 
New  Mexico. 

Georgia-Alabama  (8,  15,  16).  —  The  bauxite  deposits  of  these 
two  states,  except  those  of  Wilkinson  County,  Georgia,  noted 
below,  form  a  belt  about  60  miles  long,  extending  from  Jackson- 
ville, Alabama,  to  Cartersville,  Georgia  (Fig.  267).  The  ore, 
which  is  either  pisolitic  or  claylike  in  its  character,  forms  pockets 
or  lenses  of  variable  diameter  and  depth,  in  the  residual  clay 


752 


ECONOMIC   GEOLOGY 


derived  from  the  Knox  dolomite  (Fig.  268  and  PL  LXXIV). 
A  pronounced  feature  is  their  occurrence  close  to  900  feet  above 
sea  level,  few  being  found  above  950  feet  or  below  850  (8). 

The  bauxite  is  believed  by  Hayes  (8)  to  be  a  hot-spring  deposit. 


ML 


FIG.  267.  —  Geologic   map   of   Alabama-Georgia    bauxite   region.     (After   Hayes, 
U.  S.  Geol.  Surv.,  Wth  Ann.  Rept.,  III.) 

It  is  underlain  by  the  Knox  dolomite,  and  this  in  turn  by  the  Con- 
nasauga  shales,  which  are  several  thousand  feet  in  thickness,  and 
contain  from  15  to  20  per  cent  of  alumina  and  also  pyrite.  The 
region  is  one  of  marked  faulting.  Alteration  of  the  pyrite  by 
percolating  meteoric  waters  has  yielded  sulphuric  acid,  which 


FIG.  268.  —  Section  of  bauxite  deposit,  (a)  Residual  mantle ;  (6)  Red  sandy 
clay  soil ;  (c)  Pisolitic  ore  ;  (d)  Bauxite  with  clay  ;  (e)  Clay  with  bauxite  ;  (/) 
Talus  ;  (g)  Mottled  clay  ;  (K)  Drainage  ditch.  (After  Hayes.) 


MINOR  METALS  753 

attacked  the  alumina  of  the  shale,  with  the  formation  of  alum  and 
also  ferrous  sulphate.  Both  of  these  have  been  carried  toward  the 
surface  by  spring  waters,  but  since  they  had  to  pass  through  the 
higher-lying  limestones,  the  lime  carbonate  acted  on  the  dissolved 
alum  according  to  the  following  equation  : l  — 

A12(S04)3  +  3  CaCO3  =  A1203  +  3  CaS04  +  3  C02. 

The  alumina  thus  formed  was  a  light,  gelatinous  precipitate,  which 
was  carried  upward  into  spring  basins  on  the  surface,  where  it  finally 
settled.  The  pisolitic  structure  is  thought  to  have  been  caused  by 
the  balling  together  of  the  gelatinous  mass  by  currents. 

The  Georgia-Alabama  deposits,  which  represent  a  unique  type 
of  occurrence,  were  discovered  in  1887,  and  have  been  worked 
steadily  since  that  time.  There  have  been  some  misgivings  regard- 
ing the  exhaustibility  of  the  domestic  supply,  but  the  discovery  and 
development  of  extensive  deposits  in  Arkansas  have  allayed  these 
fears. 

Wilkinson  County,  Georgia  (14) .  —  This  new  bauxite-producing 
area  lies  within  but  near  the  margin  of  the  Coastal  Plain,  about 
30  miles  east  of  Macon  and  the  geological  relations  are  entirely 
different  from  those  of  the  principal  belt  in  "  Paleozoic  Group  " 
of  Georgia  and  Alabama.  The  bauxite  deposits,  which  occur 
apparently  near  the  contact  of  the  Tuscaloosa  (Lower  Cretaceous) 
and  Claiborne  (Tertiary)  formations,  form  beds  up  to  10  feet  in 
thickness,  and  the  ore  is  generally  either  pisolitic  or  concretionary, 
but  some  forms  exhibit  an  amorphous  character  and  even  flinty 
appearance.  The  color  varies  from  white  or  cream  to  bright 
red.  Analyses  are  given  above. 

The  origin  of  the  bauxite  is  a  somewhat  obscure  problem,  and 
as  the  field  is  but  little  developed,  evidence  is  difficult  to  secure. 
Veatch  points  out,  however,  that  all  stages  of  transition  from 
the  clay  to  the  bauxite  can  be  observed,  and  suggests  that  the 
latter  has  been  formed  by  a  desilication  of  the  kaolinite  in  the 
clay  by  circulating  meteoric  waters  carrying  some  chemical  that 
was  capable  of  abstracting  the  silica  from  the  hydrous  aluminum 
silicate. 

Tennessee  Field.  —  Deposits  of  bauxite  are  known  on  the  south- 
east slope  of  Missionary  Ridge,  near  Chattanooga  (1),  and  were 
worked  for  the  first  time  in  1907.  They  are  of  the  same  character 
as  those  found  in  the  Georgia-Alabama  field,  and  may  be  regarded 

1  For  clearness,  the  water  combined  with  alumina  is  left  out. 


754 


ECONOMIC   GEOLOGY 


as  a  northward  extension  of  that  region.  A  large  quantity  of 
ore  has  been  taken  out.  At  Keenburg,  Carter  County,  bauxite 
is  found  at  an  elevation  of  2200  feet  in  residual  clays  derived  from 
the  Watauga  shale  (Cambrian).  Much  of  the  ore  is  oolitic. 

ANALYSES  OF  BAUXITE  FROM  MISSIONARY  RIDGE,  TENN. 


1 

2 

3 

4 

5 

6 

Insoluble 

12   13 

11   15 

11.33 

11.07 

13.12 

12.65 

Loss  on  ignition 
Alumina  (AlaOs)       .     . 
Iron  oxide  (Fe2Os)  _>     . 

28.97 
57.56 
1.34 

30.04 
57.63 
1.18 

30.20 
57.37 
1.10 

30.00 
57.83 
1.10 

30.39 
55.11 
1.38 

30.31 
55  .  50 
1.34- 

Arkansas  (3,  7,  12).  —  The  occurrence  of  bauxite  in  Arkansas 
has  been  known  since  1891,  but  owing  to  a  more  accessible  eastern 
supply,  there  was  little  development  in  the  region  until  1900. 
The  deposits,  which  are  much  more  extensive  than  the  Georgia- 
Alabama  ones,  are  found  in  two  areas,  one  the  Bryant  district, 
lying  18  miles  southwest  of  Little  Rock,  and  the  other  the 
Fourche  Mountain  district,  just  south  of  Little  Rock  (12). 

The  ore  consists  of  (1)  horizontal,  tabular,  bodies  of  irregular 
outline,  which  grade  downward  into  kaolin  and  this  in  turn  into 
syenite;  and  (2)  detrital  deposits  in  Tertiary  sediments. 

The  former  is  the  more  important  type,  and  may  be  either 
pisolitic  or  granitic  in  texture.  Some  of  the  ore  is  amorphous 
or  clay  like. 

The  ore  bodies  average  about  11  feet  in  thickness  with  a  maxi- 
mum of  35  feet.  Gibbsite  occurs  chiefly  in  the  granitic  ore  and 
bauxite  in  the  pisolitic. 

Several  theories  have  been  advanced  to  explain  the  origin  of 
these  deposits.  According  to  Mead  (12),  the  syenite  was  first 
weathered  to  kaolin)  and  the  upper  and  more  porous  portions  of 
this  changed  to  bauxite  by  circulating  surface  waters.  Con- 
temporaneous with  this,  there  occurred  more  or  less  erosion, 
which  carried  much  of  the  bauxite  into  the  Tertiary  sea,  where 
it  was  deposited  with  other  sediments.  Later  the  entire  area 
became  covered  by  these  Tertiary  deposits,  after  which  another 
period  of  erosion  occurred  (Fig.  269). 

Hayes  (7)  suggested  that  the  bauxite  was  formed  by  the  action 
of  hot  alkaline  solutions  on  the  syenite. 

Other  Occurrences.  —  Bauxite  is  known  to  occur  in  Botetourt 
County,  Virginia,  in  residual  clays  with  iron  and  manganese  ores, 


MINOR  METALS 


755 


but  the  deposits  have  not  yet  proven  to  be  of  commercial  value 
(6).  Deposits  are  also  known  near  Silver  City,  New  Mexico  (2), 
and  appear  to  have  been  derived  from  a  basic  volcanic  rock  by 
decomposition  and  alteration  in  place.  Owing  to  their  remoteness 
from  the  railrcad,  they  are  of  little  commercial  importance. 


Bauxite 


Poleozafc 


FIG.  269.  —  Generalized  cross  sections  illustrating  the  geologic  history  of  the 
Arkansas  bauxite  occurrences.  A,  lens  of  bauxite  interstratified  with  the 
Tertiary  sediments;  B,  Tertiary  hill  with  bauxite  exposed  on  both  sides,  but 
prevented  from  extending  through  the  hill  by  a  rise  in  the  syenite  surface; 
C,  Tertiary  hill  with  bauxite  on  right,  but  absent  on  left;  D,  bauxite  capping 
on  syenite;  E,  hill  of  Tertiary  sediments  with  bauxite  on  both  sides,  separated 
by  Tertiary  valley  between,  in  which  is  lens  of  detrital  bauxite;  F,  Tertiary 
hill,  with  valley  exposing  underlying  bauxite;  G,  Tertiary  hill  with  concealed 
bauxite  under  it.  (After  Mead,  Econ.  GeoL,  X,  1915.) 

Foreign  Deposits.1  —  Bauxite  has  been  found  at  a  number  of  localities 
in  southern  France.  That  at  Baux,  from  which  it  is  named,  occurs  in  beds 
associated  with  Cretaceous  limestones  and  clays.  In  Germany  and  Ire- 
land it  occurs  as  a  weathering  product  of  basalt.  Other  deposits,  associated 
with  limestones,  are  found  in  Austro-Hungary  and  Italy. 

Uses  of  Bauxite.  —  The  most  important  use  of  bauxite  is  for 
the  manufacture  of  aluminum,  most  of  the  Arkansas  production 
being  employed  for  this  purpose.  A  second  important  applica- 
tion is  for  the  manufacture  of  aluminum  salts,  most  of  the 
Georgia-Alabama  product  being  sold  for  this  purpose  because 
of  its  freedom  from  iron  oxide,  but  chiefly  because  of  its  solubility 
in  sulphuric  acid  of  a  given  strength. 

Uses  of  Aluminum.  —  The  chief  use  of  this  metal  is  for  making 
wire  for  the  transmission  of  electric  currents,  but  a  large  quantity 
of  it  is  also  used  in  the  manufacture  of  articles  for  domestic  or 
culinary  use,  instruments,  boats,  and  other  articles  where  light- 

i  Dammer  und  Tietze,  Nutzbaren  Mineralien,  I:  262,  1913. 


756 


ECONOMIC   GEOLOGY 


ness  is  wanted.  It  is  also  employed  in  the  manufacture  of  special 
alloys,  among  which  may  be  mentioned  magnalium,  an  alloy  of 
aluminum  and  magnesium;  and  wolframinium,  a  tungsten-alumi- 
num alloy.  One  alloy  of  this  type,  known  as  partinium,  is  said 
to  have  a  tensile  strength  of  over  49,000  pounds  per  square  inch; 
McAdamite,  an  alloy  of  aluminum,  zinc,  and  copper,  is  said  to 
possess  a  tensile  strength  exceeding  44,000  pounds  per  square 
inch;  aluminum  silver  is  an  alloy  of  copper,  nickel,  zinc,  and 
aluminum;  aluminum  zinc  includes  a  series  of  alloys  containing 
various  proportions  of  these  two  metals.  Another  extending 
application  is  that  of  powdered  aluminum  for  the  production  of 
intense  heat  by  combustion,  and  in  this  connection  it  is  used  for 
welding  tramway  rails,  or  for  the  reduction  of  rare  metals  from 
their  oxides.  A  small  amount  of  aluminum  added  to  steel  pre- 
vents air  holes  and  cracks  in  casting,  and  it  is  also  used  to  clear 
molten  iron  and  steel  of  all  oxides  before  casting. 

Alundum,  an  artificial  abrasive,  is  made  in  large  quantities  at 
Niagara  Falls,  by  fusing  calcined  bauxite  in  the  electric  furnace. 

Bauxite  is  also  employed  for  the  manufacture  of  bauxite  bricks.1 
Still  another  application  of  bauxite  is  for  the  manufacture  of 
calcium  aluminate  to  give  a  quick  set  to  plasters.2 

Production  of  Bauxite  and  Aluminum.  —  The  production  of 
bauxite  in  the  United  States  has  been  as  follows: — 


PRODUCTION  OF  BAUXITE  IN  THE  UNITED  STATES,  1890-1914,  BY  STATES, 

IN  LONG  TONS 


YEAR 

GEORGIA 

ALABAMA 

ARKANSAS 

AND 

TENNESSE 

TOTAL 

VALUE 

1890    
1895    
1900    
1905 

1,844 
3,756 
19, 
15, 
33, 
30, 
19,587 
27, 
18, 

1,844 
17,069 
23,184 
48,129 
148,932 
155,618 
159,865 
210,241 
219,318 

$      6,012 
44,000 
89,676 
240,292 
716,258 
750,649 
768,932 
997,698 
1,069,194 

13,313 
739 
173 
996 
170 
14,173 
409 
547 

3,445 
32,956 
115,836 
125,448 
126,105 
182,832 
200,771 

1910    
1911 

1912 

1913 

1914    .      

The  table  on  page  757  shows  the  annual  production,  imports, 
consumption,  and  value  of  bauxite  in  the  United  States  during 
the  last  five  years: — 

1  Aubrey,  Min.  Indus.,  XIV:  48,  1909;  Kanolt,  Bur.  Standards,  Tech.  Pap. 
10,  1912. 

all.  S.  Geol.  Surv.,  Min.  Res.  1911,  Pt.  1:  931,  19i2. 


MINOR  METALS 


757 


PRODUCTION,  IMPORTS,  AND  CONSUMPTION  OF  BAUXITE  IN  UNITED  STATES, 
1910-1914,  IN  LONG  TONS 


YEAR. 

PRODUCTION 

IMPORTS 

CONSUMPTION 

Quantity. 

Value. 

Quantity. 

Value. 

Quantity. 

Value. 

1910          .     . 
1911           .     . 
1912           .     . 
1913           .      . 
1914          .      . 

148,932 
155,618 
159,865 
210,241 
219,318 

$    716,258 
750,649 
768,932 
997,698 
1,069,194 

15,669 
43,222 
26,214 
21,456 
24,844 

$  65,743 
164,301 
95,431 
85,746 
96,500 

164,601 
198,840 
186,079 
231,697 
244,162 

$    782,001 
914,950 
864,363 
1,083,444 
1,165,694 

World's  Production.  —  The  following  table  shows  the  world's 
production  of  bauxite  from  1911  to  1913,  inclusive:  — 

WORLD'S  PRODUCTION  OF  BAUXITE,  1911-1913,  IN  LONG  TONS 


COUNTRY 

19 

11 

19 

12 

19 

13 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

United  States    . 
France 
United  Kingdom 
Italy    .... 
India   .... 

155,618 
250,818 
6,007 
5,600 
12 

$750,649 
508,788 
6,297 
12,300 
24 

159,865 
254,851 
5,790 
6,596 
950 

$768,932 
507,649 
6,881 
20,618 
2,511 

210,241 

6,055 
6,843 
i 

$997,698 

7,606 
16,101 

i 

Total 

418  055 

1  278  058 

428  052 

1  306  591 

1  Statistics  not  available. 


The  production  of  aluminum  in  the  ^United  States  since  1885 
has  been  as  follows :  — 


PRODUCTION  OF  ALUMINUM  IN  THE  UNITED  STATES 


YEAR 

QUANITTY   IN   POUNDS 

YEAR 

QUANTITY   IN   POUNDS 

1885   

283 

1910   

i  47,734,000 

1890 

61  281 

1911 

1  46  125  000 

1895 

920  000 

1912   

1  65,607,000 

1900 

7  150  000 

1913 

1  72  379  000 

1905 

1  1  1  347  000 

1914 

1  79  129  000 

i  Conaujuptjon  1913  does  not  include  manufactured  or  leaf  aluminum  exports. 


EXPORTS  OF  ALUMINUM  FROM  THE  UNITED  STATES,  1910-1914 


1910 

$  949  215 

1913  

$  966,094 

1911 

1  158  603 

1914  

1,546,510 

1912  

1,347,621 

758  ECONOMIC  GEOLOGY 

IMPORTS  OF  "  ALUMINA  "  AND  EXPORTS  OF  ALUMINUM  FOR  CANADA,  1912-1914 


YEAR 

IMPORTS  OF  ALUMINA 

EXPORTS  OF  ALUMINUM 

INGOTS,  BARS,  ETC. 

MANUFAC- 
TURES 

Pounds 

Value 

Pounds 

Value 

Value 

1912     . 
1913     .... 
1914     .... 

22,400,500 
30,704,200 
28,557,000 

$448,061 
614,713 
571,419 

18,285,700 
13,015,000 
14,510,800 

$2,002,363 
1,762,214 
2,364,907 

$10,898 
8,203 
5,571 

No  commercial  ores  of  aluminum  have  been  found  in  Canada. 


REFERENCES  ON  ALUMINUM  AND  BAUXITE 

1.  Ashley,  Res.  of  Tenn.,  I:  211,  1911.  (Tenn.)  2.  Blake,  Amer.  Inst. 
Min  Engrs.,  Trans.  XXIV:  571,  1895.  (N.  Mex.)  3.  Branner,  Jour. 
Geol.,  V:  263,  1897.  (Ark.)  4.  Edwards,  Econ.  Geol.  IX:  112,  1914' 
(Aluminum  hydrates  in  clays);  discussion  by  Ries,  Ibid.,  p.  402.  5. 
Galpin,  Amer.  Ceramic  Soc.  Trans.  XIV:  301,  1912.  (Gibbsite  in 
fireclays.)  6.  Harder,  U.  S.  Geol.  Surv.,  Min.  Res.  1908:  699,  1909. 
(Va.)  7.  Hayes,  U.  S.  Geol.  Surv.,  21st  Ann.  Kept.,  Ill:  435,  1901. 
(Ark.)  8.  Hayes,  U.  S.  Geol.  Surv.,  16th  Ann.  Kept.,  Ill:  547,  1895. 
(Ga.,  Ala.)  9.  HoUand,  Geol.  Surv.,  India,  Records,  XXXII,  Ft.  2: 
175,  1905.  (India.)  10.  Lacroix,  Nouvelles  Archives  du  Mus4e,  Paris, 
ser.  V,  tome  V,  p.  255,  1914.  Reviewed  by  L.  L.  Fermor,  Geol.  Mag., 
Dec.  VI,  II:  28,  77,  123,  1915.  (Laterite  in  Madagascar.)  11.  Laur, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XXIV:  234,  1895.  (The  bauxites.) 
12.  Mead,  Econ.  Geol.  X:  28,  1915.  (Ark.)  13.  Phillips  and  Hancock, 
Amer.  Chem.  Soc.,  Jour.  XX:  209,  1898.  (Commercial  analysis  bauxite.) 
14.  Veatch,  Ga.  Geol.  Surv.,  Bull.  18:  430,  1909.  (Wilkinson  Co., 
Ga.)  15.  Watson,  Amer.  Geol.  XXVIII:  25,  1901.  (Ga.)  16.  Wat- 
son, Ga.  Geol.  Surv.,  Bull.  11,  1904.  (Ga.)  17.  Wetherell,  Mysore 
Geol.  Dept.,  Mem.  Ill,  Pt.  1 :  27.  (Laterite.) 


MANGANESE 

Ore  Minerals  and  Ores.  —  While  many  different  minerals  con- 
tain this  metal,  practically  the  only  ones  of  commercial  value  are 
the  oxides  and  carbonates,  and  in  this  country  only  the  former. 
The  silicates  are  not  used  as  a  source  of  manganese,  owing  to  their 
high  silica  percentage. 

The  important  ore  minerals  of  manganese  are  the  following: 
pyrolusite,  the  black  oxide  (Mn02,  63.2  per  cent  Mn);  psilo- 
melane  (chiefly  MnO2,  H20;  K  and  Ba  variable,  45  to  60  per 
cent  Mn);  braunite  (3Mn2O3,  MnSiOs,  69.69  per  cent  Mn); 
wad,  a  low-grade  earthy  brown  or  black  ore,  with  the  percentage 


MINOR  METALS  759 

of  manganese  varying  from  15  to  40  per  cent  Mn);  manganite 
(Mn203,  H20;  62.4  per  cent  Mn);  rhodochrosite  (MnCOs 
61.7  per  cent  MnO).  To  these  should  be  added  franklinite 
(FeZnMn)  O-(FeMn)203. 

The  manganese  ores  proper  consist  usually  of  a  mixture  cf 
oxides,  and  indeed  these  compounds  are  really  the  only  ones  of 
importance  in  the  United  States.  Pyrolusite  and  psilomelane 
are  by  far  the  most  important,  and  are  often  intimately  associ- 
ated, the  pyrolusite  generally  assuming  a  crystalline  and  the 
psilomelane  a  massive  structure.  They  may  locally  have  some 
admixtures  of  iron  oxide,  and  then  they  are  of  use  in  the  steel 
industry,  but  when  free  from  iron  they  are,  in  addition,  of  value 
for  oxidizing  and  coloring  purposes.  Wad  is  often  of  too  low 
grade,  due  to  impurities,  to  be  used  as  an  ore  of  manganese,  but 
it  is  sometimes  employed  for  paint.  Rhodochrosite,  though  found 
as  a  common  gangue  mineral  in  some  western  mines  (Rico,  Colo- 
rado; Butte,  Montana,  silver  mines),  can  hardly  be  regarded 
as  a  source  of  manganese.  It  has,  however,  been  mined  in  some 
quantity  in  the  Huelva  district  of  Spain,1  and  in  Merionethshire, 
Wales  (6). 

Manganese  oxides,  in  addition  to  being  associated  with  iron, 
as  noted  above,  are  sometimes  mixed  with  zinc  or  silver.  It  is 
customary,  therefore,  to  make  a  fourfold  division  into  (1)  man- 
ganese ores,  (2)  manganiferous  iron  ore,  (3)  manganif erous  silver 
ore,  and  (4)  manganiferous  zinc  residuum. 

Manganiferous  iron  ores  found  in  the  United  States  consist 
chiefly  of  limonite  or  hematite  mixed  with  psilomelane,  pyrolusite, 
or  wad,  the  mixture  being  an  intimate  one.  The  high-grade  ores 
are  of  value  for  making  spiegeleisen  or  ferro-manganese,  but  in 
those  running  low  in  manganese  this  element  is  usually  regarded 
as  an  impurity, 

Manganiferous  silver  ores  are  composed  of  a  mixture  of  manganese 
and  iron  oxides,  containing  small  amounts  of  silver  minerals,  lead 
carbonate,  and  sometimes  even  gold.  In  this  class  of  ores,  in  which 
the  iron  usually  predominates  over  manganese,  the  ores  form  the 
gossan  of  metallic  sulphide  bodies  carrying  iron,  lead,  zinc,  and 
silver  sulphides  in  a  quartz  or  calcite  gangue.  Rhodonite  and  rho- 
dochrosite sometimes  occur  in  the  unaltered  ores. 

This  class  of  ores  may  be  divided  into  three  classes  (4)  according  to  their 
uses  as  follows:    (1)  ores  used  mainly  for  their  silver  and  lead  values,  the 
iHayer,  Zeitschr.  prakt.  Geol.,  1911:  407. 


760  ECONOMIC   GEOLOGY 

manganese  and  iron  content  sometimes  insuring  a  higher  price  because  of 
their  fluxing  action ;  (2)  ores  too  low  in  silver  and  lead  to  serve  as  sources 
of  these  metals,  but  sufficiently  high  in  iron  and  manganese  to  be  employed 
in  making  ferro-manganese  and  spiegeleisen.  If  too  low  in  manganese,  it 
may  be  used  as  an  iron  ore  ;  (3)  ores  too  low  in  silver  and  lead  to  be  used  as 
sources  of  these  metals,  and  too  low  in  iron  and  manganese  to  serve  for 
alloys  of  these  two ;  such  ore  is  sold  for  flux,  and  the  lead-silver  content 
ultimately  saved. 

Manganiferous  zinc  residuum  is  obtained  from  zinc  volatilizing 
and  oxidizing  furnaces  using  New  Jersey  zinc  ores,  and  consists 
largely  of  the  iron  and  manganese  oxide  which  remains  after  the  zinc 
has  been  volatilized  and  collected  as  zinc  oxide.  The  minerals 
present  in  the  ore  are  franklinite,  zincite,  and  willemite. 

Origin  (7,  4).  —  Manganese  oxide  deposits  are  usually  of  second- 
ary origin,  having  been  formed  by  weathering  processes,  which 
caused  the  decay  of  the  parent  rock  containing  manganiferous 
silicates,  and  the  change  of  these  latter  to  oxides.  By  circulating 
ground  water  they  have  often  been  concentrated  in  residual  clays. 
Although  iron  also  may  have  been  present  in  the  parent  rock,  and 
the  two  are  sometimes  deposited  together,  still  they  have  in 
many  instances  been  separated  from  each  other,  due  to  the  fact 
that  conditions  favorable  for  precipitation  are  not  the  same  for 
both,  or  because  the  soluble  compounds  of  manganese  formed  by 
weathering  are  sometimes  more  stable  than  corresponding  iron 
compounds,  and  hence  may  be  carried  farther  by  circulating 
waters  before  they  are  deposited. 

Manganese  oxides  may  be  precipitated  from  sea-water,  as 
nodules  of  this  composition  have  been  obtained  by  dredging  from 
the  sea  bottom. 

They  are  also  known  to  occur  as  replacements  of  quartzite 
(Piedmont  region,  Virginia). 

The  carbonate  and  silicate  may  occur  as  constituents  of  ore 
veins  (Butte,  Montana)  or  as  bedded  deposits  in  sedimentary 
rocks  (Wales). 

Distribution  of  Manganese-bearing  Ores  in  the  United  States.  — 
Although  the  manganese-bearing  ores  are  widely  distributed  in  the 
United  States,  only  a  few  localities  are  of  commercial  importance, 
and  the  manganese-mining  industry  has  been  shrinking  for  several 
years. 

The  reason  for  this  is  that  the  domestic  ores  are  of  much  lower 
grade  than  the  imported  ones,  and  often  require  washing  and 
sorting  to  render  them  marketable.  Moreover,  they  occur  in  small, 


MINOR  METALS  761 

scattered  pockets,  often  remote  from  lines  of  transportation,  and 
may  carry  a  high  percentage  of  phosphorus  and  silica. 

The  demand  is  therefore  supplied  largely  by  high-grade  ores 
from  India,  Brazil,  and  Russia,  but  the  closing  off  of  many  of 
these  sources  during  the  European  war  has  stimulated  manganese 
mining  in  the  United  States. 

The  occurrence  of  the  four  classes  of  domestic  ores  may  be 
referred  to  separately. 

Manganese  Ores. — The  most  important  occurrences  of  this 
somewhat  widely  scattered  type  of  ore  are  the  Appalachian  and 
Piedmont  regions,  southern  Mississippi  Valley,  and  Pacific  coast, 
but  the  chief  producing  districts  have  been  the  James  River  Valley 
and  Blue  Ridge  regions  in  Virginia;  Cave  Springs  and  Cartersville 
districts  in  Georgia;  Batesville  district,  Arkansas;  and  the  Liver- 
more-Tesla  district  in  California. 

Eastern  Area.  —  Manganese  deposits  are  found  in  the  Atlantic 
states  from  Vermont  to  Alabama,  and  two  states  in  this  belt, 
Georgia  and  Virginia  (17,  6),  lead  in  the  domestic  production. 
In  the  crystalline  rocks  of  the  Piedmont  province,  deposits  of 
commercial  value  have  been  proven  only  in  Virginia.  In  this 
state  the  manganese  area  lies  chiefly  northeast  and  southwest  of 
Lynchburg.  The  ore  minerals  are  mostly  granular  pyrolusite  and 
psilomelane,  commonly  occurring  as  nodules  in  residual  clays  from 
mica  schists,  quartzite  and  limestones  of  Cambrian  age.  Umber 
is  sometimes  present.  In  several  mines  where  the  workings  have 
extended  into  hard  rock,  the  ore  occurs  near  the  contact  of  quartz- 
ite, at  times  replacing  the  latter.  Crystalline  limestone  is  found 
closely  associated  with  the  ore  deposits,  but  its  relations  to  the  ore 
are  not  definitely  known.1 

The  Appalachian  Valley  deposits  occur  in  two  districts,  viz., 
the  Blue  Ridge  and  New  River. 

The  ores  of  the  first  district,  which  are  the  most  important 
of  the  two,  occur  in  a  series  of  irregularly  distributed  deposits 
along  the  west  foot  of  the  Blue  Ridge  from  Front  Royal  to 
Roanoke,  a  distance  of  about  150  miles.  This  same  belt  in- 
cludes the  Blue  Ridge  iron-ore  deposits,  which  may  sometimes 
contain  an  appreciable  amount  of  manganese.  So,  too,  iron 
may  be  found  in  the  manganese  deposits. 

The  manganese  ore  occurs  in  pockets  in  clays  of  residual  or  sedi- 
mentary character,  along  the  contact  of  the  Lower  Cambrian 

1  Supplied  by  T.  L.  Watson. 


762 


ECONOMIC   GEOLOGY 


quartzite   with    the   overlying    formation,   and   more   rarely   in 
fissures  penetrating  the  quartzite. 

Four  types  of  ore  are  found,  all  of  which  may  occur  in  the  same  deposit. 
They  are:  (1)  black  psilomelane  kidneys  in  clay;  (2)  irregular,  often  porous 
masses  of  psilomelane  with  layers  of  crystalline  pyrolusite,  also  in  clay; 
(3)  breccia  ore  in  larga  masses  consisting  of  sandstone  or  chert  fragments, 
with  pyrolusite  or  psilomelane  filling;  (4)  replacements  or  cavity  fillings, 
mainly  pyrolusite,  in  sandstone  or  sandy  clay.  The  mine  at  Crimora 
(Fig.  270  and  Plate  LXXII)  is  one  of  the  best  known.  The  ore  forms  pockets 
5  to  6  feet  thick,  and  20  to  30  feet  long  in  a  deposit  of  clay  276  feet  thick. 


SECTION    NO.  2. 


SECTION   NO.  4. 


FIG.  270.  —  Sections  of  Manganese  deposit.  Crimora,  Va.      (After  Hall.) 

In  the  New  River  district,  the  ore,  which  is  mainly  psilomelane, 
occurs  as  large  masses  mixed  with  iron  ores  in  residua]  clay,  but 
is  of  little  commercial  importance. 

The  Virginia  areas  mentioned  extend  southward  into  Tennes- 
see, and  some  ore  is  mined  there,  (6,  9a) 


FIG.  271.  —  Map  showing  Georgia  manganese  areas.     (After  Watson,  Amer.  Inst. 
Min.  Engrs.,  Trans.  XXXIV.) 


. 

il 


764 


ECONOMIC   GEOLOGY 


Georgia.  «=-*•  In  northern  Georgia  (7,  16)  the  ore  results  from  the 
decay  of  limestones  and  shales,  Cave  Spring  and  Cartersville 
being  important  localities  (Fig.  271).  The  deposits  are  found  in 
the  areas  underlain  by  both  the  crystalline  and  Palaeozoic  rocks, 
but  only  those  associated  with  the  latter  have  proven  to  be  of 
importance.  In  this  region  the  rocks  consist  of  Cambro-Silurian 
limestones  and  quartzites,  which  have  been  much  folded  and 
faulted,  and  have  been  weathered  down  to  a  residual  clay,  which 
is  often  not  less  than  100  feet  thick.  The  ore  occurs  as  pockets, 
lenticular  masses,  stringers,  grains,  or  lumps,  irregularly  scattered 
through  the  clay,  and  rarely  forming  distinct  beds.  None  of  the 
deposits  are  large,  though  some  30  feet  in  length  have  been  worked. 


^pro-paleozoio 


FIG.  272. —  Section  in  Georgia  manganese  area,  showing  geologic  relations  of 
nlanganese,  limonite,  and  ocher.  (After  Watson,  Amer.  Inst.  Min.  Engrs. 
Trans.  XXXIV}. 

More  or  less  limonite,  barite,  ocher,  and  bauxite  may  be  associated 
with  the  ore  (Fig.  272), and, indeed,  complete  gradations  from  man- 
ganese to  iron  are  found,  as  shown  by  the  following  analyses: 


Mn 

60.61 

54.94 

41.98 

15.26 

2.30 

Fe  .     .     .     .     . 

1.45 

3.62 

16.22 

39.25 

52.02 

P     ..... 

.052 

.034 

227 

193 

24 

The  better-grade  ores  are  usually  low  in  silica,  iron,  and  phosphorus. 
In  the  Cartersville  district,  which  is  the  more  important,  the  ore  is 
found  in  residual  clays  derived  from  the  Beaver  limestone  and  Weis- 
ner  quartzite,  while  in  the  Cave  Spring  area  it  occur  only  in  the  clays 
overlying  the  Knox  dolomite. 

Penrose  (10)  thought  that  the  manganese  was  derived  from  the 
underlying  Cambro-Silurian  sediments,  while  Watson,  on  the  con- 
trary, believes  that  the  crystalline  rocks  to  the  east  and  south  have 
furnished  the  ore,  as  none  is  found  in  the  parent  rock  from  which 
the  clays  were  derived.  The  manganese  was  probably  taken  into 
solution  as  a  sulphate,  and  concentrated  by  circulating  waters  of 
meteoric  origin  in  the  residual  clays  where  now  found. 


PLATE    LXXIV 


FIG.  1.  —  View  of  bauxite  bank,  Rock  Run,  Ala.     (H.  Ries,  photo.) 


FIG.  2.  —  Furnace  for  roasting  mercury  ore,  Terlingua,  Tex.    (H.  W.  Turner,  photo.) 

(765) 


766 


ECONOMIC   GEOLOGY 


The  Georgia  (15)  deposits  have  been  worked  for  a  number  of 
years,  and  the  manganese  was  formerly  marketed  chiefly  in 
England;  but  the  output  is  now  sold  entirely  in  the  United  States. 
The  ore,  which  has  to  be  purified  by  washing  and  crushing,  is  used 
in  part  for  paint  and  in  part  for  steel  manufacture. 

Other  Eastern  Occurrences.  —  Deposits  are  known  at  several 
localities  in  Vermont  (6),  North  Carolina,  (G)  South  Carolina  (6), 
and  Pennsylvania  (6). 

Lower  Mississippi  Valley  and  Gulf  Region.  —  The  Arkansas 
deposits  are  the  only  important  ones  in  this  region. 

Arkansas.  —  Manganese  ore  is  found  in  the  region  around 
Batesville  (10,  13),  associated  with  horizontally  stratified  lime- 
stones and  shales,  ranging  from  Ordovician  to  Carboniferous  Age 
(Fig.  273).  The  Cason  shale,  of  Silurian  Age,  occurring  near  the 


Residual  Clay 
{•  Carboniferous 

Silurian 
Ordovician 


FIG.  273.  —  Section  in  Batesville,  Ark.,  manganese  region,  illustrating  geological 
structure  and  relation  of  different  formations  to  marketable  and  non-market- 
able ore.  (After  Van  Ingen,  Sch.  of  M,  Quart,,  XXII.). 


middle  of  the  section  (Fig.  2736),  carries  manganese  nodules  high 
in  phosphorus,  which  are  not  marketable,  and  others  are  found 
in  the  pits  of  residual  clay  derived  from  it.  Farther  down  the 
slopes  marketable  ore  (Fig.  273c),  which  has  been  derived  by 
leaching  of  the  first-mentioned  ore,  is  found  occurring  in  residual 
pockets  in  the  lower-lying  limestones,  while  the  residual  clays 
(Fig.  273a),  formed  at  a  higher  level  than  the  Cason  shale,  are 
barren  of  manganese. 

Other  Occurrences.  —  Small  deposits  are  said  to  occur  in  Hick- 
man  County,  Tennessee,  and  Llano  County,  Texas. 

Western  States.  —  Two  types  of  ore  are  found  in  California. 
The  first  of  these  consist  of  veins  of  pyrolusite,  and  psilomelane 
in  the  Calaveras  (Carboniferous)  formation,  occurring  near 
Meadow  Valley,  Plumas  County,  and  at  other  points  in  the 
Sierra  Nevada.  The  second  occurs  near  the  coast  north  and  south 


MINOR   METALS  767 

of  San  Francisco,  as  local  thin  lenses,  interbedded  with  jaspers 
of  the  Franciscan  (Jura-Trias)  formation.  At  the  Ladd  mine 
near  Livermore,  the  ore  lies  in  a  fault  fissure,  4  to  5  feet  in  width, 
and  forms  cavity  fillings,  infiltrations,  and  replacement  deposits 
in  red  and  yellow  clays,  and  as  veins  and  breccia  cement  in  the 
wall.  The  wall  rock  is  jasper  (6). 

Small  deposits  are  also  known  in  Utah  where,  in  Grand  County, 
the  ore  occurs  as  replacements  in  Triassic  limestone  (6),  and  near 
Golconda,  Nevada.  The  latter,  which  is  bedded,  and  is  inter- 
stratified  with  calcareous  and  siliceous  tufa,  appears  to  be  a  hot- 
spring  deposit  in  a  small  tufa  basin. 

Manganiferous  Iron  Ores.  —  Those  of  the  Appalachian  Valley 
have  already  been  referred  to  in  connection  with  the  manganese 
ores.  The  most  important  deposits  are  in  Vermont,  Virginia 
and  Tennessee,  and  consist  chiefly  of  psilomelane  and  limonite 
mixtures.  Much  iron  ore  of  the  Lake  Superior  district  carries 
from  1  to  10  per  cent  metallic  manganese,  and  some  large  bodies 
are  known  on  the  Cuyuna  range.  Other  occurrences  have  been 
noted  from  Gunnison  County,  Colorado  (10),  Juab  County,  Utah, 
and  Missouri,  but  they  are  not  of  commercial  value. 

Manganiferous  Silver  Ores.  —  The  most  important  deposits 
are  those  found  at  Leadville,  Colorado.  Manganiferous  silver 
and  iron  ores  are  important  in  the  oxidized  zone  of  the  Leadville 
district,  forming  large  masses  adjacent  to  the  sulphide  deposits. 
Some  (4)  have  suggested  that  they  represented  infiltrations  from 
the  porphyry,  but  P.  Argall  (l)  has  shown  that  manganiferous 
siderite  in  irregular  masses  is  abundant  as  a  limestone  replace- 
ment. He  therefore  suggests  that  weathering  of  the  siderite  has 
yielded  the  manganese.  The  ores  range  as  follows:  Manganese, 
trace-40  per  cent;  iron,  8-50  per  cent;  lead,  trace-5  per 
cent;  insoluble,  5-34  per  cent;  silver  (in  1914)  2-25  ounces 
per  ton;  gold,  trace.  Ores  of  similar  character  are  found  at 
Neihart  and  Castle,  Montana.  Manganese  is  also  found  in  the 
silver  veins  at  Butte,  Montana,  but  is  of  little  commercial  value. 
Still  other  manganiferous  silver  ores  have  been  noted  from 
scattered  localities  in  New  Mexico,  Arizona,  Utah,  and  Nevada, 
but  appear  to  be  of  little  commercial  importance.  Some  found  in 
the  Tintic  district,  Utah,  are  used  as  flux  at  the  local  smelters. 

Canada  (8).  —  The  Canadian  production  is  very  small.  A 
number  of  scattered  deposits  are  known  in  Nova  Scotia,  New 
Brunswick,  and  Quebec. 


768  ECONOMIC   GEOLOGY 

Other  Foreign  Deposits  (6).  —  Russia1  is  by  far  the  largest  producer, 
most  of  the  ore  coming  from  the  Sharopan  district  of  the  Caucasus, 
where  it  occurs  as  a  stratified  deposit  of  oolitic  oxides  between  Eocene  sand- 
stone and  Cretaceous  limestone.  The  beds  do  not  exceed  a  foot  in  thickness, 
but  the  ore  is  high  grade. 

India.  —  Much  manganese  ore  is  mined  in  the  Madras  and  Bombay 
Presidencies  of  Central  India.2  The  ores  are  all  oxides  and  occur:  (1)  Asso- 
ciated with  or  derived  from  manganese-bearing  silicates,  as  bands  or  lenticles, 
in  Archaean  gneisses  and  schists;  (2)  as  superficial  formations  on  the  out- 
crops of  such  rocks  as  quartzites,  shales,  slates,  and  hematite-schists;  and 
(3)  as  concretions  in  laterite. 

Brazil*  the  third  largest  world's  producer,  has  important  deposits  in  the 
province  of  Minas  Geraes.  The  manganese  is  associated  with  iron  ores; 
and  may  be  of  bedded  character  or  detrital  nature. 

Uses  of  Manganese.  —  Manganese  is  used  in  the  manufacture  of 
alloys,  whose  value  depends  not  only  on  the  amount  of  manganese, 
but  also  on  the  absence  of  sulphur  and  phosphorus.  Spiegeleisen 
contains  under  20  per  cent  manganese,  and  ferromanganese,  a  similar 
alloy,  has  from  20  to  90  per  cent  of  it.  The  amount  of  silicon  and 
carbon  present  in  these  varies. 

Other  alloys  are  manganese  bronze,  manganese  and  copper,  with 
or  without  iron.  Some  alloys  of  manganese,  aluminum,  and  copper, 
known  as  Heusler's  alloys,  are  important  because  of  their  magnetic 
properties.  Other  elements  alloying  with  manganese  are  zinc,  tin, 
lead,  magnesium,  and  silicon. 

Manganese  oxide  is  used :  ( 1)  as  a  substitute  for  iron  oxide  in  copper 
and  silver  reduction ;  (2)  as  an  oxidizing  agent  in  the  manufacture 
of  chlorine,  bromine,  and  disinfectants ;  (3)  as  a  decolorizer  of  green 
glass ;  (4)  as  a  coloring  agent  in  calico  printing  and  dyeing,  in  the 
making  of  glass,  pottery,  bricks,  and  also  paints ;  (5)  in  the  manufac- 
ture of  the  Leclanche  battery  and  of  dry  cells,  for  which  purpose  a 
considerable  amount  is  consumed  annually. 

Some  manganese  compounds  have  a  medicinal  value,  and  rhodon- 
ite is  sometimes  cut  for  a  gem  stone. 

Production  of  Manganese.  —  Although  much  used  in  steel  manu- 
facture, the  domestic  production  is  small  because  of  the  inferior 
character  of  the  native  ores,  therefore  the  largest  consumers  rely 
upon  foreign  sources  of  supply. 

1  Cauldwell,    Min.    and   Sci.   Pr.,   CV:   113,    1912.     Harder,   Amer.  Inst.  Min. 
Engrs.,  Bull.  113,  1916. 

2  Fermor,  Geol.  Surv.,  India,  Mem.  XXXVII,  1909. 
s  Harder  loc.  cit.   p.  785. 


MINOR  METALS 


769 


The  following  table  gives  the  total  quantity  of  the  several  kinds 
of  ore  produced  in  the  United  States.  The  annual  production 
since  1885  has  fluctuated  more  or  less,  and  there  has  been  a  strong 
decline  in  the  production  of  the  straight  manganese  ores. 

PRODUCTION   OF  MANGANESE  ORES  IN  THE  UNITED  STATES,  1912  TO  1914, 

IN  LONG  TONS 


YEAR 

MANGANESE 

MANGANIFEROUS 
IRON  ORE  AND 
MANGANIFEROUS 
SILVER  ORE 

MANGANIFEROUS 
ZINC 
RESIDUUM 

1912  1                 .... 

819,883 

48,618 

104,670 

1913 

622  393 

49,753 

102,239 

1914         

405,946 

39,881 

100,198 

1  From  1909  to  date  the  U.  S.  Geological  Survey  has  not  given  separate  returns  for 
the  several  classes  of  ore. 

MARKETED  PRODUCTION  OF  MANGANESE  ORE  IN  THE  UNITED  STATES,  1912 
TO  1914,  BY  STATES,  IN  LONG  TONS 


1912 

1913 

1914 

STATE 

fcj 

«      § 

N 

H 

«      § 

H 

H 

55 
H       0 

EH 
B 

ft 

(3 

K  2  K 

i 

B 

3§H 

g 

H 

t> 

UM 

(9 

•< 

^  —  - 

s 

<< 

^AnS 

p 

!^ 

*fi  2 

•< 

a 

^ 

O1 

> 

^ 

California 

1 

I 









2 

2 



South  Carolina 

1 

1 









2911 

2  $8,812 

$9.67 

Virginia     . 

11664 

i$15.73 

$9.45 

M048 

s$40,480 

$10.00 

1724 

18,565 

10.77 

Total       . 

1664 

$15,723 

9.45 

4048 

$40,480 

$10.00 

2635 

$27,377 

$10.39 

1  Virginia  includes  California  and  South  Carolina. 

2  South  Carolina  includes  California. 

3  Includes  small  quantity  produced  in  1911  and  1912,  but  not  reported  for  those  years. 

The  average  price  per  long  ton  for  Colorado  manganiferous 
silver  ores  in  1914  was  $2.86,  silver  content  inclusive,  and  of 
manganiferous  zinc  residuum,  $2.63. 

The  prices  of  manganese  ores  used  in  the  steel  industry  normally 
vary  from  $8  to  $13.50  per  long  ton,  according  to  grade,  but 
during  the  war  manganese  has  commanded  much  higher  prices. 

They  are  governed  by  the  following  schedule  of  prices  established  by  the 
Carnegie  Steel  Comapny,  the  price  being  for  delivery  at  Pittsburgh  or  South 
Chicago. 

Prices  are  based  on  ores  containing  not  more  than  8  per  cent  silica  or 
.20  per  cent  phosphorus,  and  are  subject  to  deductions  as  follows:  For 
each  1  per  cent  in  excess  of  8  per  cent  silica  there  shall  be  deduction  of  15 
cents  per  ton;  fractions  in  proportion. 

For  each  .02  per  cent,  or  fraction  thereof,  in  excess  of  .20  per  cent  phos- 
phorus, there  shall  be  a  deduction  of  2  cents  per  unit  of  manganese  per  ton. 


770 


ECONOMIC   GEOLOGY 


Ores  containing  less  than  40  per  cent  manganese  or  more  than  12  per 
cent  silica  or  .225  per  cent  phosphorus  are  subject  to  acceptance  or  refusal 
at  the  buyer's  option. 


PERCENTAGE  OF  METALLIC 
MANGANESE  IN  ORE 


PRICE  PER  UNIT  OF 
MANGANESE  IN  CENTS 

2o 


Over  49 

46  to  49 ,     -v    .  .  25 

43  to  46 .     .     .     .  .  24 

40  to  43 .V    ,    ,  .  23 

Settlements  are  based  on  analysis  of  sample  dried  at  212°  F.,  the  per- 
centage of  moisture  in  the  sample  as  taken  being  deducted  from  the  weight. 

The  manganese  ores  for  oxidizing  and  coloring  purposes  are  valued  ac- 
cording to  the  quantity  of  manganese  peroxide  present,  their  consistency, 
etc.  An  ore  for  use  as  an  oxidizer  must  contain  at  least  80  per  cent  man- 
ganese dioxide,  and  not  more  than  1  per  cent  iron.  There  is  no  established 
schedule,  and  such  ores  have  usually  been  obtained  largely  from  the  Caucasus 
region  of  Russia.  Owing  to  the  war,  prices  went  as  high  as  $70  a  ton.  Few 
deposits  in  the  United  States  can  supply  this  demand. 

Manganiferous  iron  ores  containing  15  to  35  per  cent  manganese  range 
from  $3.50  to  $6  per  ton. 

The  imports  in  1913  amounted  to  345,090  long  tons  valued 
at  $2,029,680,  and  in  1914  to  283,294  long  tons  valued  at 
$2,024,120.  These  came  chiefly  from  Brazil,  British  India, 
Russia,  and  the  United  Kingdom. 

The  production  of  Canada  in  1914  amounted  to  28  short  tons 
valued  at  $1120.  The  exports  for  the  same  year  were  30  short 
tons,  valued  at  $750. 

World's  Production.  —  The  following  table  gives  the  latest 
available  statistics  with  regard  to  American  and  foreign  production 
of  manganese  ore. 

WORLD'S  PRODUCTION  OF  MANGANESE  ORE,  IN  LONG  TONS 


COUNTRY 

YEAR 

QUANTITY 

COUNTRY 

YEAR 

QUANTITY 

North  America: 
Canada 

1914 

25 

Eupore  —  Continued  : 
Russia 

1913 

1  289  370 

Nova  Scotia    . 

1912 

208 

Spain      

1913 

21  254 

United  States       .     . 
South  America: 
Brazil     

1914 
1913 

2,635 

180  738 

Sweden  
Turkey  
United  Kingdom 

1913 
1910 
1914 

3,938 
12,008 
3  439 

Europe  : 
Austria  

1913 

16  280 

Asia: 
India 

1913 

718  520 

Bosnia  and  Herze- 

Japan      

1912 

11,862 

govina     .... 
France    
German  Empire  . 
Greece    
Hungary     .... 
Italy       

1913 
1913 
1911 
1913 
1913 
1913 

4,626 
7,610 
85,921 
547 
18,706 
1,596 

Africa: 
Cape  Colony  . 
Natal      
Oceanica: 
Australia     .... 
j      New  Zealand 

1911 
1910 

1914 
1910 

116 
51 

6 
5 

MINOR  METALS  771 


REFERENCES    ON    MANGANESE 

1.  Argall,  P.,  Min.  and  Sci.  Pr.,  CIX:  50,  128,  1914.  (Leadville,  Colo.)  2. 
Dolhear,  Min.  and  Sci.  Pr.,  CX:  172,  1915.  (Calif,  industry.)  Also  ibid., 
258.  (Ladd  mine,  Calif.)  3.  Eddingfield,  Econ.  Geol.,  VIII:  498,  1913. 
(Manganese  in  superficial  alteration.)  4.  Emmons  and  Irving,  U.  S.  Geol. 
Surv.,  Bull.  320:  34,  1907.  (Leadville,  Colo.)  5.  Hafer,  Eng.  and  Min. 
Jour.,  XCVIII:  1135,  1914.  (S.  Ca.)  6.  Harder,  U.  S.  Geol.  Surv.,  Bull. 
427,  1910.  (U.  S.)  7.  Hayes,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXX:  403, 
1901.  (Ga.)  8.  Kramm,  Can.  Min.  Inst.,  XV:  210,  1913.  (New  Ross, 
N.  S.)  9.  Leith,  U.  S.  Geol.  Surv.,  Bull.  285:  17,  1906.  (Utah.) 
9a.  Nelson,  Min.  Res.  Tenn.,  I,  No.  6,  1911.  (Tenn.)  96.  Penrose, 
Jour.  Geol.  I:  275,  1893.  (Chemical  relations  of  iron  and  manganese 
in  sedimentary  rocks.)  10.  Penrose,  Ark.  Geol.  Surv.,  Rept.  for  1890, 
Vol.  I,  1891.  (Uses,  ores,  and  deposits.)  11.  Tarugi,  Eng.  and  Min. 
Jour.,  July  12,  1913.  (Use  of  siliceous  manganese  minerals.)  12.  Van 
Hise  and  Leith,  U.  S.  Geol.  Surv.,  Mon.  LII,  1911.  (L.  Superior  region.) 
13.  Van  Ingen,  Sch.  of  M.  Quart.,  XXII:  318,  1901.  (Batesville, 
Ark.)  14.  Wallace,  Min.  and  Sci.  Pr.,  CHI:  201,  1911.  (Low. 
Calif.)  15.  Watson,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXIV:  207,, 
1904.  (Ga.)  16.  Watson,  Ga.  Geol.  Surv.,  Bull.  14:  158,  1908. 
(Ga.)  17.  Watson,  Min.  Res.  Va.,  1907:  235.  (Va.)  18.  Young, 
Can.  Geol.  Surv.,  Mem.  18,  1911.  (Bathurst  dist.,  N.  B.) 

MERCURY 

Ore  Minerals.  —  While  mercury  is  sometimes  found  native  in 
the  form  of  quicksilver,  the  most  common  ore  is  cinnabar  (HgS), 
which  contains  86.2  per  cent  mercury.  Native  amalgam  of  mer- 
cury and  silver  is  known,  and  calomel,  the  chloride,  as  well  as 
other  compounds,  are  sometimes  found. 

Among  the  less  common  ones  may  be  mentioned:  montroydite 
(HgO);  tiemannite  (HgSe);  onofrite  (Hg(S,Se));  and  coloradoite 
(HgTe)4.  Schwatzite,  the  mercurial  tetrahedrite,  is  not  uncom- 
mon, being  known  from  a  number  of  localities  in  Europe  and 
South  America.  In  the  United  States  it  is  known  in  the  Blue 
Mountains,  Oregon,  and  may  have  been  the  original  ore  mineral, 
whose  decomposition  formed  the  present  mercurial  ore  minerals 
at  some  other  localities  (Plomosa  district.  Arizona  and  La  Plata 
district,  Colorado). 

The  commercial  sources  of  mercury  contain  a  comparatively 
small  amount  of  other  metallic  minerals,  although  a  number  of 
different  ones  have  been  found  and  cinnabar  may  at  times  occur 
in  small  quantities  in  veins  of  the  other  metals.  Thus  it  is  a 
frequent  accompaniment  of  stibnite,  and  is  also  found  in  some 


772  ECONOMIC   GEOLOGY 

gold  and  copper  deposits.  The  dyscrasite  found  in  the  Cobalt, 
Ontario,  silver  veins,  also  carries  mercury. 

Mode  of  Occurrence.  —  Mercury  ores  are  not  confined  to  any 
particular  formation,  but  are  found  in  rocks  ranging  from  the 
Ordovician  to  Recent  age  in  different  parts  of  the  world.  Nor 
are  they  peculiar  to  any  special  type  of  rock,  although  igneous 
rocks  are  often  found  in  the  vicinity  of  them.  They  occur  as 
veins,  disseminations,  or  as  masses  of  irregular  form.  Silica, 
either  crystalline  or  opaline,  and  calcite  are  common  gangue 
minerals,  while  pyrite  or  marcasite  are  rarely  wanting,  and 
bitumen  is  widespread. 

Many  mercury  deposits  occur  along  lines  of  fissuring,  and  these 
may  be  marked  by  hot  springs. 

The  commercially  valuable  occurrences  have  apparently  been 
deposited  at  shallow  depths,  although  mercury  minerals  are  some- 
times found  ift  small  quantities  of  the  intermediate  and  even 
deeper  vein  zone. 

Origin.  —  The  origin  of  mercury  ores  has  been  studied  chiefly 
by  Becker  (3)  and  later  by  Schrauf  (17).  The  former  points  out 
that  silica  (either  crystalline  or  amorphous)  and  calcite  are 
common  gangue  minerals,  but  pyrite  or  marcasite  are  almost 
equally  abundant,  as  is  also  bitumen.  In  addition  to  these,  the 
ores  show  an  irregular  association  with  other  metallic  minerals, 
such  as  antimony,  silver,  lead,  copper,  arsenic,  zinc,  or  even  gold. 
Becker  believes  that  the  cinnabar  has  been  precipitated  from 
ascending  waters  by  bituminous  matter,  having  come  up  in 
solution  as  a  double  sulphide  with  alkaline  sulphides.  He  further 
suggests  that  the  deposits  represent  impregnations  and  are  not 
replacements. 

Hot  springs  carrying  mercury  in  solution  are  known  at  Steam- 
boat Springs,  Nevada  (PL  XXXIX,  Fig.  2),  and  Sulphur  Bank, 
California. 

Distribution  in  the  United  States.  —  California  has  always 
been  the  most  important,  and  in  fact,  at  times,  the  only  pro- 
ducing state.  Deposits  are,  however,  also  known  in  Texas, 
Oregon,  Utah,  Nevada,  New  Mexico,  and  Arizona. 

California  (3,  4)  (Fig.  274).  —  The  California  ores  occur  chiefly 
in  metamorphosed  Cretaceous  or  Jurassic  rocks,  with  some  in  the 
Miocene  and  even  Quaternary.  The  deposits,  which  are  termed 
"  chambered  veins "  by  Becker,  are  fissured  zones.  Eruptive 
rojcks  seem  in  many  cases  to  be  involved  in  the  ore  formation, 


MINOR  METALS 


773 


and  at  New  Almaden  a  rhyolite  dike  runs  parallel  with  the  ore 
body.  The  ore  here  occurs  along  the  contact  between  serpentine 
and  shale,  filling  in  part  the  interstices  of  a  breccia.  These  mines, 
which  are  the  largest  in  the  state,  have  been  worked  to  a  depth  of 
over  2,500  feet. 

At  the  New  Idria  mine, 
located  in  southeastern 
San  Benito  County,  and 
which  has  been  worked 
almost  continually  since 
1853,  the  ore  bodies  occur 
as  stockworks  in  meta- 
morphic  rocks  of  Lower 
Cretaceous  age,  just  south 
of  their  contact  with  the 
unaltered  sediments  o  f 
the  Chico  (Lower  Creta- 
ceous) formation.  The 
ore,  which  consists  of  a 
mixture  of  pyrite  and  cin- 
nabar, with  a  gangue  of 
silicified  and  brecciated 
metamorphic  sandstones 

and  shales,  may  occur  as  veins,  stockworks  or  impregnations. 
It  is  interesting  to  note  that  in  driving  a  tunnel  to  connect 
with  the  1060-foot  level  considerable  natural  gas  was  en- 
countered, and  that  at  another  locality,  New  Almaden,  exhala- 
tions of  carbon  dioxide  were  encountered  in  some  of  the  lower 
levels. 

Other  occurrences  are  in  Colusa  County,  where  the  cinnabar  is  found  in 
altered  serpentine,  and  in  Napa  County,  where  it  occurs  along  the  contact 
of  sandstone  and  slate.  The  minerals  associated  with  these  are  bitumen, 
free  sulphur,  stibnite,  mispickel,  gold  and  silver,  chalcopyrite,  pyrite, 
millerite,  quartz,  calcite,  barite,  and  borax.  The  vein  is  a  fissure  filled 
with  brecciated  fragments,  and  cuts  through  sandstone,  shale,  and  augite 
andesite,  the  cinnabar  cementing  the  breccia  together,  but  at  times  also 
impregnating  the  walls.  Hot  waters  which  circulate  through  the  vein 
still  deposit  gelatinous  silica. 

At  Steamboat  Springs  the  waters  carry  gold,  sulphide  of  arsenic,  anti- 
mony, and  mercury,  sulphides  or  sulphates  of  silver,  lead,  copper,  zinc, 
iron  oxide,  and  possibly  other  metals.  They  also  contain  sodium  carbon- 
ate, sodium  chloride,  sulphur,  and  borax. 

Cinnabar  is  known  in  Lane  and  Douglas  counties,  Oregon. 


FIG.  274.  —  Map  of  California  mercury 
localities. 


774 


ECONOMIC  GEOLOGY 


Texas  (6,  14,  19) .  — The  Terlingua  district  of  Brewster  County, 
Texas  (Fig.  275),  has  aroused  much  interest  in  recent  years. 

The  area  of  importance  is  about  two  miles  wide  north  and 
south  and  fifteen  miles  east  and  west,  and  lies  in  southern 
Brewster  County,  about  300  miles  southeast  of  El  Paso,  and 
110  miles  south  of  Marfa.  It  is  7  miles  to  the  Rio  Grande  and 


FIG.   275.  —  Map   showing   Texas  mercury  region.     (After  Hill,   Eng.  and  Min 

Jour.,  LXXIV.} 

Mexican  border.  The  remoteness  from  the  railroad  and  lack  of 
water  have  formed  serious  obstacles  in  the  development  of  the 
district. 

The  rocks  are  sediments  of  Upper  and  Lower  Cretaceous 
age  cut  by  Tertiary  volcanics,  and  the  following  section  is 
involved : 

Tertiary  tuffs  and  lavas,  forming  sheets,  dikes,  laccoliths,  and  surface  flows. 

The  rock  types  included  are  andesites,  rhyolites,  phonolites,  and  basalts. 
Upper  Cretaceous. 

Ponderosa  marls 200  ft. 

Austin  chalk 100  ft. 

Eagle  Ford  shales 400  ft. 

Lower  Cretaceous.  J 

Vola  limestone 75  ft. 

Arietina  clays  or  Del  Rio  shales        75  ft. 

Washita  or  Fort  Worth  limestone 100  ft. 

Fredericksburg  or  Edwards  limestone 1000  ft. 

There  has  been  important  faulting,  the  strike  of  the  chief  dislo- 
cation being  northwest-southeast,  but  that  of  the  ore-filled  fissures 
is  northeast-southwest. 


MINOR  METALS 


775 


The  ore  bodies  have  thus  far  been  found  chiefly  in  the  Washita 
and  Fredericksburg  limestones,  but  more  recently  in  the  Eagle  Ford 
shales.     The  ore  is  most  frequentty  found  in  fissure  veins  (Fig.  277) , 
but    some     occurs    in 
breccias  and  as  lateral- 
enrichment  deposits. 

The  chief  ore  mineral 
is  cinnabar,  which  is 
often  closely  associated 
with  pyrite  or  its  oxida- 
tion products,  especially 
in  the  breccia  lodes. 
Calcite  is  the  most  im- 
portant gangue  mineral. 
Gypsum  (probably  sec- 
ondary) is  common  and 
hydrocarbons  may  be 
present.  It  is  of  inter- 
est to  note  that  three 
new  minerals,  terlinguaite,  eglestonite,  and  montroydite,  all  oxy- 

chlorides  of  mercury,  were  discov- 
ered in  these  ores. 

The  ore  treated  in  the  furnaces 
varies  from  .75  to  2.5  per  cent 
mercury,  while  ,  that  sent  to  the 
retorts  runs  4  per  cent  or  over. 

Most  of  the  workings  are  open 
pits,  there  being  few  shafts,  so  no 
definite  idea  of  the  underground 
reserves  exists. 


VERTICAL  SECTION  CALIFORNIA  HILL. TERLINGUA 


FIG.    276.  —  Vertical    section    of    California    Hill, 
Terlingua,  Tex.     (After  Turner,  Econ.  GeoL,  /.) 


FIG.  277.  —  Section  of  cinnabar 
vein  in  limestone,  Terlingua,  Tex. 
(After  Phillips,  Univ.  Tex.  Min. 
Sun.,  Bull.  4). 


Foreign  Deposits.1  —  Spain  is  the  largest  producer,  followed  by  Italy  and 
Austria.  In  the  first-named  country,  the  Almaden  deposit  is  the  world's 
greatest  producer.  Here  the  ore  forms  impregnations  and  replacements  of 
three  steeply  dipping  beds  of  Silurian  quartzite.  The  principal  bed  is  8 
to  14  meters  thick,  and  the  ore  averages  about  8  per  cent  mercury.  This 
deposit,  unlike  most  others,  extends  to  a  considerable  depth. 

At  Monte  Amiata  in  Tuscany  the  ore  occurs  as  disseminations,  chimneys, 
etc.,  in  Cretaceous  and  Tertiary  limestones,  shales  and  sandstones  associated 
with  trachyte. 

A  third  large  deposit  is  that  at  Idria,  Austria,  where  the  ore,  chiefly  cin- 
nabar, but  sometimes  native  mercury,  is  found  forming  impregnations, 

1  Vogt,  Krusch  and  Beyschlag,  Translation  by  Truscott,  I:  464,  1914. 


776 


ECONOMIC   GEOLOGY 


stockworks  and  veins  in  limestones,  shales,  marls,  and  dolomites  of  Triassic 
age.  There  seems  to  be  a  connection  between  the  ore  deposition  and  a 
large  overthrust  of  post-Cretaceous  times. 

Mexico  and  Peru  contribute  some  mercury  to  the  world's  production. 


FIG.  278.  —  Thin  section  of  limestone  impregnated  and  replaced  (?)  by  cinnabar, 
Idria,  Austria.      X33. 


Uses  of  Mercury.  Quicksilver  is  used  chiefly  in  the  manu- 
facture of  electric  appliances,  drugs,  scientific  apparatus,  and 
fulminate  for  explosive  caps.  About  one-third  of  the  domestic 
output  is  said  to  be  employed  for  the  last-named  purpose  in 
normal  times.  It  is  used  in  decreasing  quantity  for  the  recovery 
of  precious  metals,  especially  gold,  because  of  the  increased  use 
of  the  cyanide  process,  the  decrease  of  free-milling  gold  ores  and 
placer  gravels,  and  the  increased  efficiency  and  economy  in  stamp  - 
milling,  resulting  in  a  decreased  loss  of  quicksilver.  Mercuric 
oxide  (red  oxide  of  mercury)  is  the  active  poison  in  antifouling 
paint  for  ships'  bottoms.  Quicksilver,  though  formerly  much 
used  for  silvering  mirrors,  is  now  largely  replaced  by  silver 
nitrate 

Extraction.  —  Cinnabar  is  easily  decomposed  by  heat,  giving  off  when 
heated  in  air,  or  retorted  with  quicklime,  the  mercury  vapors  and  sulphur 
dioxide  in  one  case,  or  mercury,  calcium  sulphide,  and  calcium  sulphate  in 
che  other. 

The  mercury  is  collected  by  subsequent  condensation. 


MINOR   METALS 


777 


Retorts  are  adapted  only  to  ores  carrying  4  per  cent  or  more  of  mercury, 
while  low-grade  ores  are  treated  in  shaft  furnaces,  some  of  the  more  modern 
ones  being  capable  of  treating  an  ore  running  as  low  as  .25  per  cent  metal. 

Production  of  Mercury.  —  California  was  for  many  years  prac- 
tically the  only  domestic  source  of  mercury,  but  in  1898  Texas 
became  a  producer,  and  will  no  doubt  continue  so.  The  output 
of  mercury  is  quoted  in  flasks  of  75  pounds  net. 

PRODUCTION  OF  QUICKSILVER  IN  THE  UNITED  STATES,  1912,  1913,  AND  1914, 
BY  STATES,  IN  FLASKS  OF  75  POUNDS 


STATE 

1912 

1913 

1914 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

Arizona    . 
California 
Nevada    . 
Texas  .... 
States  not  shown 
separately  2    . 

Total 

20,524 
i 

4,540 

$863,034 

i 

190,907 

15,591 
1,645 

2,977 

$627,228 
66,178 

119,765 

i 
11,303 
2,089 

i 

3,156 

i 
$554,414 
102,465 

i 

154,801 

25,064 

$1,053,941 

20,213 

$813,171 

16,548 

$811,680 

1  Included  in  States  not  shown  separately. 

2  Nevada  and  Texas  combined  in  1912;,  Arizona  and  Texas  in  1913  and  1914. 

In  addition  to  the  production  from  ore  and  furnace  material 
(soot  and  cleanings)  given  above,  there  is  an  annual  output  of 
secondary  metal  from  the  clean-up  of  old  gold  and  silver  amal- 
gamation mills  and  from  other  sources.  This  probably  tends  to 
reduce  the  market  for  new  metal  only  to  a  small  degree. 

The  average  domestic  price  of  quicksilver  per  flask  in  San 
Francisco  in  1914  was  $49.05. 

The  imports  in  1913  amounted  to  171,653  pounds,  valued  at 
$75,361,  while  those  of  1914  amounted  to  614,869  pounds,  valued 

QUICKSILVER  ORE  TREATED  IN  RETORTS  AND  IN  FURNACES  IN  1914,  BY 

STATES 


STATE 

ORE  TREATED, 
SHORT  TONS 

QUICKSILVER 
RECOVERED, 
FLASKS 

PERCENTAGE  OF 
METAL  RECOVERED 
PER  TON  OF  ORE 
TREATED 

Retorts 

Furnaces 

Retorts 

Furnaces 

Retorts 

Furnaces 

California 
Nevada    ... 
Other  States  l    . 

Total      . 

4411 
1110 
4 

97,142 
13,001 
7,330 

367 
544 
6 

10,936 
1,545 
3,150 

0.31 
1.84 
5.63 

0.42 
.45 
1.61 

5255 

117,473 

917 

15,631 

.62 

.50 

Arizona  and  Texas. 


778 


ECONOMIC   GEOLOGY 


at  $271,984.  The  exports  for  1913  were  1140  flasks,  valued  at 
$43,574,  while  those  for  1914  included  1446  flasks,  valued  at 
$70,753.  The  exports  went  to  nearly  all  parts  of  the  world. 

The  imports  are  greater  than  formerly  while  the  exports  are 
less. 

WORLD'S  PRODUCTION  OF  QUICKSILVER,  1911-1914,  IN  FLASKS  OF 
75  POUNDS  EACH 


COUNTRY 

1911 

1912 

1913 

1914 

United  States  

21,256 

25,064 

20,213 

16,548 

Austria-Hungary 
Italy  

23,310 
27,367 

23,016 
28,983 

i  26,720 
1  29,513 

2 

1  3  22,340 

Russia     .     .     <.  •..     . 
Spain       
Mexico  and  other  countries 

3  43,681 
*  4,409 

3  43,799 
*  4,409 

3  43,799 
*  4,409 

2 

2 

Total     ...... 

120,023 

125,271 

124,654 



*  The  Mineral  Industry. 
2  Statistics  not  available. 


3  Export  figures  only. 

4  Estimated. 


In  recent  years  the  world's  production  has  probably  exceeded  the  demand, 
but  at  the  outbreak  of  the  war  the  foreign  sources  of  supply  were  cut  off 
from  the  United  States. 


REFERENCES    ON    MERCURY 

1.  Bancroft,  U.  S.  Geol.  Surv.,  Bull.  451,  1911.  (Yuma  Co.,  Ariz.)  2. 
Bancroft,  Ibid.,  Bull.  430:  153,  1910.  (Plomosa  dist.,  Ariz.)  3.  Becker, 
Geology  of  Quicksilver  Deposits  of  Pacific  Slope,  U.  S.  Geol.  Surv., 
Mon.  XIII,  1888.  4.  Becker,  U.  S.  Geol.  Surv.,  Min.  Res.,  1892: 
139,  1893.  (Origin.)  5.  Forstner,  Calif.  State  Min.  Bur.,  Bull.  27, 
1903  (Calif.),  also  Eng.  and  Min.  Jour.,  LXXVIII:  385  and  426,  1904. 

6.  Hillebrand  and  Schaller,   Jour.  Amer.  Chem.  Soc.,  XXIX:    1180, 
1907,  and  U.  S.  Geol.  Surv.,  Bull.  405,  1910.     (Terlingua,  Tex.,  minerals.) 

7.  Knopf,   U.   S.   Geol.   Surv.,   Bull.   620,    1915.     (Nev.)     8.  Leconte, 
Amer.  Jour.  Sci.,  XXIV:    23,  1882,  and  XXV:    424,  1883.     (Sulphur 
Bank,  Calif.)     9.  Lindgren,  U.  S.  Geol.  Surv.,  22d  Kept.,  Pt.  2:    604, 
1901.     (Blue    Mts.,    Ore.)     10.  McCaskey,    U.    S.    Geol.    Surv.,    Min. 
Res.     1911.     (Very  complete  bibliography  and   General.)     11.  Miller, 
Eng.  and  Min.  Jour.,  XCII:    645,   1911.     (Mercury  in  Cobalt  ores.) 

12.  Moses,  Amer.  Jour.  Sci.,  XVI:    253,  1903.     (New  minerals,  Tex.) 

13.  Pagliucci,  F.  D.,  Eng.  and  Min.  Jour.,  Feb.  18,  1905.     (Huitzuco, 
Mex.)     14.  Phillips,  Univ.  Tex.  Min.  Surv.,  Bull.  4,  1902,  also  Econ. 
Geol.  I:    155,   1905.     (Tex.)     15.  Ransome,  U.  S.  Geol.   Surv.,   Bull. 
620,  1915.     (Mazatzal  Range,  Ariz.)     16.  Rundall,  W.  H.,  Eng.  and 
Min.  Jour.,  1895,  p.  607.     (Guadalcazar,  Mex.)     17.  Schrauf,  Zeitsch. 
prak.    Geologic,    II:     10,    1894.     (Origin.)     18.  Stafford,    Bull.    Univ. 
Ore.,  new  ser.,  I,  No.  4,'  1904.     (Ore.)     19.  Turner,  Econ.  Geol.,   I: 
265,  1905.     (Tex.) 


CHAPTER  XXI 

/ 

MINOR   METALS  (Continued) 

ANTIMONY  TO  VANADIUM 

ANTIMONY 

Ore  Minerals.  —  Stibnite  (Sb2S3)  is  the  most  important  ore  of 
antimony,  and  the  metal  is  rarely  obtained  from  any  other  mineral, 
although  native  antimony  has  been  sparingly  found.  The  oxide 
senarmontite  (Sb2Os)  seldom  occurs  in  any  quantity.  A  small 
amount  of  antimony  is  present  in  some  silver-lead  ores.  The 
stibnite,  together  with  a  gangue  of  quartz,  and  frequently  calcite, 
usually  forms  veins  cutting  igneous,  sedimentary,  or  metamorphic 
rocks,  and  less  often  is  found  in  replacement  deposits.  Other 
metallic  sulphides  may  be  associated  with  the  antimony;  some 
deposits  are  auriferous,  and  less  often  argentiferous. 

Stibnite  is  not  necessarily  a  mineral  of  the  shallow-vein  zone, 
for  it  may  occur  in  deposits  formed  at  intermediate  depths,  or 
even  in  the  deep-vein  zone,  but  commercial  deposits  occur  chiefly 
in  the  shallow  zone. 

Cairnes  (2)  classifies  antimony  deposits  as  follows: 

I.  Ores  deposited  in  cavities,  chiefly  fissure  veins, 
a.  Of  value,  chiefly  or  entirely  for  antimony 
6.  Auriferous  stibnite. 
c.  Antimony  and  silver. 
II.  Replacement,  chiefly  in  limestone. 

Distribution  of  Antimony  in  United  States.  —  Antimony  has 
been  found  at  a  number  of  localities  in  the  Cordilleran  region, 
but  the  great  distance  of  the  deposits  from  the  railroad  has  helped 
to  make  them  of  little  commercial  value,  and  the  domestic  pro- 
duction is  very  small  and  irregular. 

It  is  therefore  only  the  richest  and  best-located  deposits  that 
are  worked.  Some  of  the  known  ore  bodies  are  also  said  to  lack 
value  because  of  their  content  of  arsenic,  zinc,  or  lead  minerals, 

779 


780  ECONOMIC  GEOLOGY 

and  hence  are  refused  by  the  buyers  so  long  as  they  can  get  purer 
ores  (Hess). 

Many  gold  and  silver  ores  carry  some  antimony,  and  in  smelt- 
ing it  combines  with  the  lead,  giving  a  product  known  as  anti- 
monial  lead,  much  of  which  is  produced  in  the  United  States. 

The  large  amount  of  antimony  now  manufactured  in  the 
United  States  is  obtained:  (1)  as  a  by-product  from  the  smelting 
of  foreign  and  domestic  lead-silver  ores  containing  small  quan- 
tities of  antimony;  (2)  from  antimony  regulus,  or  metal  from 
foreign  countries;  (3)  from  foreign  ore;  and  (4)  from  some  copper 
ores. 

Hess  states  that  in  1914  a  few  tons  were  separated  from  the 
anode  muds  of  blister  copper  made  from  Butte  ores. 

Very  little  has  been  published  regarding  the  occurrence  of  anti- 
mony ores  in  the  United  States.  Hess  has  described  some  deposits 
in  Arkansas  (4),  where  the  antimony  occurs  as  bedded  veins  in 
sandstones  and  shales,  with  a  quartz  gangue,  and  associated  with 
a  number  of  different  metallic  minerals.  The  deposits  are  of 
doubtful  value,  except  possibly  when  high  market  prices  prevail. 
Along  Coyote  Creek,  in  Garfield  County,  Utah  (7),  there  are 
found  flat-lying  deposits  of  stibnite  and  its  oxidation  products 
in  Eocene  (Tertiary)  sandstone  and  conglomerates.  The  ore  in 
sight  is  all  low  grade,  although  some  rich  pockets  have  been 
worked  out  in  the  past. 

Stibnite  veins  in  rhyolites  and  basalts  are  known  in  western 
Nevada,  and  have  been  specially  referred  to  in  the  National 
district  (6).  There,  the  fissures,  which  have  a  quartz  gangue, 
all  carry  more  or  less  stibnite,  together  with  small  amounts  of 
pyrite,  blende,  etc. 

Canada.  —  The  Canadian  production  of  antimony  is  small  and 
spasmodic. 

It  occurs  at  West  Gore,  Nova  Scotia  (4)  in  fissure  veins  in 
Cambrian  slates.  The  minerals  are  stibnite,  native  antimony, 
pyrite  (auriferous),  mispickel,  kermesite  (Sb2S20)  in  a  gangue  of 
crushed  slate,  quartz  and  calcite.  Other  veins  are  found  at  Prince 
William,  near  Fredericton,  New  Brunswick,  (8).  An  interesting 
series  of  veins  in  granite  is  found  in  the  Wheaton  River  district, 
Yukon  Territory.  The  veins,  which  occur  chiefly  in  granite  and 
vary  from  a  few  inches  to  5  feet  in  width,  carry  stibnite,  sphalerite, 
tetrahedrite,  argentiferous  galena  and  antimony  ochre,  in  a  gangue 
of  quartz  (2). 


MINOR   METALS 


781 


Other  Foreign  Deposits.  —  China  is  the  largest  producer  of  the  world, 
the  deposits  of  the  Hunan  Province  *  being  of  importance.  There  the  ore 
near  Hsinhua  is  distributed  in  seams,  pockets  and  bunches  in  Carboniferous 
dolomite,  while  at  the  Pan-shi  mines  it  occurs  as  fissure  veins  in  sediments. 

France  has  also  been  a  large  producer,  numerous  deposits  being  found  in 
the  Central  Plateau  region.  The  veins,  which  cut  schists,  granite,  and  also 
elastics,  carry  stibnite  in  a  quartz  gangue. 

The  Japanese  veins  are  found  chiefly  in  Mesozoic  and  Paleozoic  sediments, 
often  near  quartz  prophyry,  or  even  in  it. 

Replacement  deposits  are  known  in  Italy,2  Algeria,3  and  Mexico.4 

Uses.  —  Antimony  metal  is  used  chiefly  in  the  manufacture  of 
alloys  of  lead,  tin,  zinc,  etc.  Type  metal,  which  is  an  alloy  of  lead, 
antimony,  and  bismuth,  has  the  property  of  expanding  at  the  mo- 
ment of  solidification.  Britannia  metal  is  tin  with  10  to  16  per  cent 
antimony  and  3  per  cent  copper.  Babbitt,  or  antifriction  metal 
consists  of  antimony  and  tin,  with  small  amounts  of  lead,  copper, 
bismuth,  zinc,  and  nickel.  Tartar  emetic,  a  potassium-antimony 
tartrate,  antimony  fluoride  and  ammonium  sulphide,  and  other 
double  salts  are  used  in  medicine  and  as  a  mordant  for  dyeing,  while 
antimony  persulphide  is  employed  for  vulcanizing  and  coloring 
rubber.  Antimony  trioxide  is  employed  as  a  substitute  for  white 
lead,  zinc  oxide,  etc.,  in  pigments.  It  is  also  used  in  a  glaze  for  coat- 
ing enameled  iron  ware,  as  a  reducing  agent  in  chemical  work,  and 
as  a  detector  of  alkaloids  and  phenols.  The  trichloride  is  used  in 
bronzing  gun  barrels,  in  coloring  zinc  black,  and  as  a  mordant  for 
patent  leather  and  silver.  Antimony  trisulphide  is  used  in  pyro- 


PRODUCTION  OF  ANTIMONY  IN  THE  UNITED  STATES,  1912-1914,  IN 
SHORT  TONS 


CONTAINED  IN 

CONTAINED  IN 

ANTIMONIAL  LEAD 

RECOVERED  FROM 

ANTIMONIAL  LEAD 

OF  FOREIGN  ORIGIN, 

OLD  ALLOYS,  SCRAP, 

YEAR 

OF  DOMESTIC  ORIGIN 

BUT  SMELTED  IN 

DROSS,  ETC. 

UNITED  STATES 

Quantity 

Value 

Quantity 

Value 

Quantity 

Value 

1912    .... 

.  1224 

i  $209,059 

725 

i  $123,830 

2506 

1  $428,025 

1913     .... 

2204 

1  375,562 

304 

i  53,801 

2705 

i  460,932 

1914     .... 

2530 

i  529,740 

175 

i  36,750 

2645 

1  555,450 

1  Estimated,  using  the  average  price  for  the  year. 

1  Wheeler,  Eng.  and  Min.  Jour.,  CI:   637,  1916. 

2  Bergeat,  Erzlagerstatten,  II:  883. 

3  Fuchs  and  de  Launay ,  Giles  Mineraux,  2 :   205. 

4  Cox,  Amer.  Jour.  Sci.,  XX:  421,  1880;   Halse,  Trans.  Fed.  Inst.  Min.  Engrs., 
VI:  290,  1893-1894. 


782 


ECONOMIC   GEOLOGY 


technics    for   making  "  Bengal   fire."     Antimony   chromate,    or 
"  Naples  yellow,"  if  used  for  coloring. 

Production  of  Antimony.  —  The  production  of  metallic  anti- 
mony from  domestic  and  foreign  ores  since  1912  was  as  shown 
in  the  table  on  page  781. 

ANTIMONY,  ANTIMONY  ORE,  AND  SALTS  OF  ANTIMONY  IMPORTED  AND 
ENTERED  FOR  CONSUMPTION  IN  THE  UNITED  STATES,  1912-1914,  IN 
POUNDS 


YEAR 

1  METAL  (REGULUS) 

2  CRUDE  ANTIMONY 
AND  ORE 

OXIDE  AND  SALTS 
OF  ANTIMONY 

TOTAL 
VALUE 

Quantity 

Value 

Quantity 

Value 

Quantity 

Value 

1912 
1913 
1914 

13,936,873 
12,479,727 
13,110,426 

$808,473 
798,581 
736,420 

1,562,066 
4,021,486 
2,606,349 

$   51,444 
137,780 
75,345 

3  1,759,908 
*  1,968,475 
2,744,406 

$   81,077 
117,169 
315,001 

940,994 
1,053,530 
1,126,766 

1  ''Regulus"  is  a  term  which  has  been  handed  down  from  the  alchemists  and  should  be 
allowed  to  become  obsolete.     As  now  used  it  merely  "means  metal,"  so  that  "antimony," 
"regulus,"  and  "refined  antimony,"  which  from  year  to  year  are  noted  in  the  reports  of 
various  governments,  are  redundants. 

2  "Crude  antimony"  is  an  awkward  and  misleading  term  meaning  "liquidated  stibnite." 
It  is  also  known  as  "needle  antimony." 

3  Oxide  only.     No  figures  showing  the  imports  of  antimony  salts  were  given  in   the 
customs  returns. 

4  Includes  imports  of  salts  for  the  last  three  months  of  1913. 

The  last  reported  production  of  antimony  in  Canada  was  in 
1909  and  consisted  of  364  tons  of  antimony  concentrates,  valued 
at  $13,906,  shipped  from  West  Gore,  Nova  Scotia. 

The  imports  of  antimony  into  Canada  in  1914  amounted  to 
694,130  pounds,  valued  at  $57,715. 


WORLD'S  PRODUCTION  OF  ANTIMONY  IN  1912 
(In  metal  unless  otherwise  noted.     Tons  of  2000  pounds.) 


1912 

1912 

5  139 

Australia: 
New  South  Wales  (ore  and 
metal)   

71 

"Crude"  and  metal    . 
Ore        
Italy  (ore)   

047 

72 
2  070 

Victoria  (ore)      .... 
Austria  (ore)     ..... 

2,722 
4,983 

Japan: 
Crude  

14 

Bolivia  (ore)      

100 

Refined     . 

69 

China,  exports: 
Metal  

14,914 

Mexico: 
Ore        .... 

17 

Ore        
France  (ore)      

2,265 
12,147 

Metal  
Portugal  (ore)       .... 

3,849 
110 

Servia  (ore)      
Spain  (ore) 

327 
551 

MINOR   METALS  783 

In  1914  the  value  of  the  antimony  content  of  antimonial  lead 
was  10.5  cents  per  pound. 

REFERENCES    ON    ANTIMONY 

1.  Cairnes,  Can.  Geol.  Surv.,  Mem.  37,  1913.  2.  Cairnes,  Can.  Min.  Inst., 
XIII:  297,  1911.  (Wheaton  River,  Yukon  Ter.)  3.  Comstock,  Ark. 
Geol.  Surv.,  Ann.  Rept.  for  1888,  I:  136.  (Ark.)  4.  Haley,  Eng.  and 
Min.  Jour.,  LXXXVIII:  723,  1909.  '  (West  Gore,  N.  S.)  U.  S.  Geol. 
Surv.,  Bull.  340;  241,  1908.  5.  Hess,  (Ark.);  also  articles  on  Anti- 
mony, U.  S.  Geol.  Surv.,  Min.  Res.  6.  Lindgren,  U.  S.  Geol.  Surv., 
Bull.  601,  1915.  (National  dist,  Nev.)  7.  Richardson,  Ibid.,  Bull. 
340:  253,  1907.  (Utah.)  8.  Young,  Can.  Geol.  Surv.,  Geology  and 
Economic  Minerals  of  Canada  (N.  B.) 

ARSENIC 

Ore  Minerals.  —  Although  arsenic-bearing  minerals  are  widely 
distributed  in  many  countries,  the  commercially  valuable  occur- 
rences are  few,  and  moreover  few  arsenic-bearing  minerals  are 
important  as  sources  of  the  metal.  Arsenopyrite  (FeAsS  with 
46.02  As)  is  the  most  important  and  the  most  widely  distributed 
of  the  arsenic  minerals.  It  may  occur  in  schists,  gneisses,  peg- 
matites, contact-metamorphic  deposits  or  quartz  veins,  and 
usually  favors  deep-zone  conditions.  Other  sulphides  may  be 
associated  with  it,  as  well  as  gold  and  silver. 

Orpiment  (As2Ss,  60.96  As)  and  realgar  (As2S2,  70.08  As)  may 
be  both  original  and  secondary  minerals,  formed  usually  at  shallow 
depths,  but  comparatively  unimportant  as  ores,  although  con- 
siderable quantities  of  the  latter  are  said  to  be  mined  in  China  (4) . 
The  two  occur  in  some  quantity  also  at  Mineral  Creek,  Lewis 
County,  Washington. 

Native  Arsenic,  though  occasionally  found,  is  never  in  com- 
mercial quantities,  and  the  oxides  arsenolite  and  claudetite,  of 
secondary  nature,  are  likewise  unimportant. 

Arsenic  is  found  combined  with  a  number  of  metals,  or  with  a 
metal  and  sulphur  in  many  primary  ore  deposits.  Among  the 
better  known  of  these  compounds  occurring  in  ore  deposits  of  the 
United  States  or  Canada  alone,  may  be  mentioned  enargite 
(CuaAsS-i),  tennantite  (CugAs2S7),  proustite  (AgGA^Se),  smaltite 
(CoAs2),  niccolite  (NiAs),  chloanthite  (NiAs2),  cobaltite  (CoAsS), 
and  sperrylite  (PtAs2) .  Of  these,  the  enargite  is  the  second  most 
important  ore  mineral  at  Butte,  Montana. 

Great  quantities  of  arsenic  are  lost  annually  in  this  country 
by  allowing  it  to  pass  off  with  the  smelter  fumes,  and  it  has  been 


784  ECONOMIC  GEOLOGY 

estimated  that  from  14,000  to  15,000  tons  of  arsenic  trioxide  are 
being  set  free  from  the  Butte  ores  every  year.  Hess  states  that 
other  localities  in  the  United  States  probably  supply  an  additional 
5000  tons  annually. 

Distribution  in  the  United  States.  —  Little  has  been  published 
on  the  occurrence  of  arsenic  .ores  in  the  United  States,  and  indeed 
there  appear  to  be  comparatively  few  discovered  deposits  of  com- 
mercial importance.  Arsenopyrite  has  been  mined  in  Washington, 
where  the  mineral  is  used  for  making  arsenious  oxide.  The  ore 
is  said  to  average  about  14  per  cent  arsenic,  .7  ounce  gold  and  3 
ounces  silver  per  ton. 

In  Virginia  (9),  arsenopyrite  has  been  found  at  Rewald,  Floyd 
County.  The  material  occurs  as  a  series  of  lenses  in  quartz- 
sericite  schist,  the  principal  lens  being  3  feet  at  the  surface,  but 
thickening  to  14  feet  at  a  depth  of  120  feet.  In  Rockbridge 
County,  in  the  same  state,  the  arsenopyrite  is  found  in  association 
with  pyrite  and  cassiterite  in  quartz-greisen-bearing  tin  veins, 
but  "it  is  not  worked. 

Arsenopyrite  and  subordinate  pyrite  with  a  quartz  gangue, 
forming  a  series  of  parallel  stringers  in  gneiss,  close  to  a  basic 
dike,  is  found  near  Carmel,  Putnam  County,  N.  Y.  (5).  The 
product  of  the  mine  when  concentrated  averages  25  per  cent 
arsenic. 

A  number  of  these  occurrences  are  known  but  they  are  not 
worked.  (See  references.)  White  arsenic  has  been  produced  at 
Everett,  Washington,  since  1901,  but  as  all  the  white  arsenic  is 
made  in  the  West,  and  the  markets  are  in  the  East,  the  product 
has  to  compete  with  Canadian  and  other  foreign  supplies. 

Foreign  Deposits.  —  White  arsenic  is  made  as  a  by-product  in  Canada, 
being  saved  by  the  smelters  at  Thorold,  Copper  Cliff,  and  Orillia,  Ontario, 
from  arsenical  silver  ores  from  Cobalt,  Ont. 

White  arsenic  has  been  produced  at  Mapimi,  Mex. 

Uses  of  Arsenic.  —  Arsenopyrite  is  used  chiefly  for  the  manu- 
facture of  arsenious  oxide.  Arsenic  is  employed  in  medicine,  as 
a  pigment,  and  as  an  alloy  with  lead  for  making  shot.  Arsenious 
oxide  is  used  for  making  paris  green,  in  glassware  for  counter- 
acting the  iron  coloration,  in  certain  enamels,  and  as  a  fixing  and 
conveying  substance  for  aniline  dyes.  It  is  also  important  as  a 
weed  killer.  Realgar,  the  disulphide,  is  used  in  printing,  tan- 
ning, and  also  in  pyrotechnics,  since  it  burns  with  a  white  light. 
Orpiment  is  used  chiefly  in  textile  dyeing. 


MINOR  METALS 


785 


Production  of  Arsenic.  —  The  production  and  imports  from  all 
sources  are  given  below. 

PRODUCTION  AND  IMPORTS  OF  ARSENIC,  UNITED  STATES,  1912-1914 


YEAR 

PRODUCTION  OF 
WHITE  ARSENIC 

IMPORTS 

"ARSENIC  OR  ARSENI- 

IOUS    ACID"    AND 

"ARSENIC  AND  AR- 
SENIC SULPHIDE  OR 
ORPIMENT" 

PARIS  GREEN  AND 
LONDON  PURPLE 

Short  Tons 

Value 

Short  Tons 

Value 

Pounds 

Value 

1912     . 
1913     .... 
1914     .... 

3141 
2513 
4670 

$190,757 
159,236 
313,147 

6156 
4701 
3628 

$428,741 
410,446 
273,713 

162,272 
99,692 
15,476 

$6950 
4431 
2235 

The  production  of  white  arsenic  in  Canada  in  1914  was  1,737 
short  tons,  valued  at  $104,015.  The  exports  for  1914  amounted 
to  18}  tons,  valued  at  $132,567. 


WORLD'S  PRODUCTION  OF  ARSENIC,   1911-1912,  BY  COUNTRIES,  IN  SHORT 

TONS 


COUNTRY 

1£ 

11 

19 

12 

Quantity 

Value 

Quantity 

Value 

Great  Britain: 
Arsenopyrite 

1  310 

$     6  276 

9  4Q1 

70  124 

Canada  1 

2097 

$76  237 

2  045 

89  262 

China: 

Orpiment  —  exports  2    . 
France  (arsenopyrite)  3   . 
Germany  (arsenic  ore)     . 
Japan  (metal)    . 

366 

5356 

7 

23,138 

105,084 
384 

377 
24,369 

21,635 
656,775 

Portugal   

987 

I  1  R  A 

38,356 

1,047 

45,416 

United  States     ....           ! 

3132 

73.408 

3,142 

190,757 

1  McLeish,  John,  Annual  report  on  the  mineral  production  of  Canada  during  the  calendar 
year  1913.     Ottawa,  p.  191,  1914. 

2  "Orpiment,   yellow   sulphide   (As2S3),   is   obtained   from    mines   near   Chaochow   and 
Menghua,   in  the  Tali  prefecture,   about  24   miles  from  Hsia   Kuan,  in  the  province  of 
Yunnan.      In  1912,  273  metric  tons  (301  short  tons)  were  exported  from  Teng  Yuek;  and 
69  tons  (75  short  tons)  from  Mengtsz."      The  exports  as  given  in  the  Reports  of  the  Mari- 
time Customs  of  China  give  no  orpiment,  but  call  it  realgar. 

3  Large  quantities  of  arsenical  gold  ore — in  1912,  165,380  metric  tons,  valued  at  9,574,000 
francs,  and  in  1911  162,499  metric  tons,  valued  at  8,055,000  francs — were  mined  in  France, 
but  no  statement  is  made  of  the  quantity  of  white  arsenic  in  the  ore  or  saved.     See 
Statistique  de  1'industrie  minerale  et  des  appareils  a  vapeur  en  France  et  en  Algerie  pour 
1'annee  1912,  Paris,  pp.  32  and  34,  1914. 

4  Estimate,  Mineral  Industry,  1912,  p.  45. 

6  Mineral  Industry,  1913,  p.  32,  gives   Spain  credit  for  331  metric  tons  of  white  arsenic 
in  1911. 


786  ECONOMIC   GEOLOGY 


REFERENCES    ON    ARSENIC 

1.  Dunn,  Amer.  Inst.  Min.  Engrs.,  Trans.  XLVI:  687,  1914.  (Smelter 
gases.)  2.  Hess,  U.  S.  Geol.  Surv.,  Min.  Res.,  1913:  953,  1914.  3. 
Hess,  U.  S.  Geol.  Surv.,  Bull.  470:  205,  1911.  (Brinton,  Va.)  4.  Hess, 
U.  S.  Geol.  Surv.,  Minn.  Res.,  1914,  Pt.  I:  947,  1916.  (General.) 
5.  Newland,  N.  Y.  St.  Mus.,  Bull.  120:  12,  1908.  (N.  Y.)  6.  Richard- 
son, U.  S.  Geol.  Surv.,  Bull.  340:  255,  1908.  (S.  Utah.)  7.  Spencer, 
U.  S.  Geol.  Surv.,  Bull.  450:  54,  1911.  (Llano-Burnet  region,  Tex.) 
8.  Spurr,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  Pt.  2:  837,  1901.  (Monte 
Cristo,  Wash.)  9.  Watson,  Min.  Res.  Va.,  1907:  210.  (Va.)  10. 
Weed  and  Pirsson,  Amer.  Jour.  Sci.,  XLII:  403,  1891.  (Orpiment  and 
realgar,  Yellowstone  Park.)  11.  Wells,  Ont.  Bur.  Mines,  XI:  101, 
1902.  (Ont.)  See  also  Cobalt,  Ont.,  refs.  under  Nickel.) 


BISMUTH 

Ore  Minerals.  —  The  principal  ores  of  this  metal,  together  with 
percentage  of  metallic  bismuth  which  they  contain,  are:  Bis- 
muihinite  (61283,  81.2);  bismite  (B'^Os,  66.6);  and  bismutite 
(Bi2O3,  C02,  H2O,  80.6).  Although  all  of  these  contain  a  high 
percentage  of  metallic  bismuth,  the  content  of  the  ore  as  mined 
does  not  usually  exceed  ten  or  fifteen  per  cent.  Native  bismuth 
is  likewise  found  at  a  number  of  localities. 

Bismuth  ore  minerals  are  almost  invariably  associated  with 
other  metallic  minerals,  which  are  the  primary  object  of  min- 
ing operations,  the  bismuth  being  a  by-product  obtained  in  the 
treatment  of  these. 

Distribution  of  Bismuth  in  the  United  States.  —  Very  little 
bismuth  ore  is  mined  as  such  in  the  United  States,  and  in  1914 
the  only  locality  reported  producing  it,  was  one  in  the  Clifton 
district,  Tooele  County,  Utah.  Bismuth  occurs  in  some  of 
the  Tintic,  Utah,  lead  and  copper  ores,  and  is  saved  at  the  elec- 
trolytic lead-refining  plant  at  Grasselli,  Ind.  Some  was  also 
separated  at  Omaha,  Neb.  Experiments  (1,  3)  show  that  the 
flue  dust  of  Anaconda,  Mont.,  smelter  carried  1.15  per  cent 
bismuth  trioxide,  and  amounted  to  about  275  tons  per  year. 
This  may  be  saved  in  the  future.  Similar  quantities  might 
be  recovered  elsewhere. 

Some  of  the  gold  ores  on  Breece  Hill  near  Leadville,  Colorado, 
carry  as  much  as  5  to  8  per  cent  bismuth,1  and  nearly  all  of  the 
gold  ores  at  Goldfield,  Nevada  (q.v.),  carry  this  metal,  partly 

1  George  Argall,  private  communication. 


MINOR  METALS 


787 


in   the   form  of  bismuthinite.     Other  western  ores  also  carry 
bismuth. 

Foreign  Deposits.  —  The  deposits  of  economic  value  in  foreign  countries 
are  comparatively  few.  The  mines  of  Schneeberg,  Altenberg,  Annaberg 
and  Johann-Georgenstadt,  in  Saxony,  have  contributed  considerable  bismuth 
ore  in  the  past.  The  bismuth  here  is  chiefly  native.  At  Schneeberg  the  ores 
are  chiefly  in  cobalt-bearing  veins.  At  Joachimsthal,  Austria,  the  metal 
occurs  in  argentiferous  veins.  Bismuth  as  native  metal,  ochre  and  carbon- 
ate, associated  with  gold,  silver  and  tin,  have  been  found  at  Tasna  and 
Chorolque,  Bolivia.  The  former  occurrence  is  in  slates,  and  the  latter  in 
porphyry.  This  country  is  the  world's  chief  source  of  supply.  At  Meymac, 
France,  bismuth  ores  have  been  found  in  veins  in  granite,  together  with  wolf- 
ramite and  arsenopyrite. 

The  only  Australian  colony  producing  bismuth  in  any  quantity  is  Queens- 
land. 

In  New  South  Wales  native  bismuth,  and  bismuthinite  associated  with 
molybdenite  in  quartz  gangue,  forms  pipes  in  granite  in  the  Kingsgate  dis- 
trict (5). 

Uses  of  Bismuth.  —  Bismuth  is  chiefly  valuable  on  account 
of  the  easily  fusible  alloys  which  it  forms  with  lead,  tin,  and 
cadmium;  the  melting-point  of  some  of  these  lies  between  64°  C. 
and  94.5°  C.  They  are  therefore  employed  in  safety  fuses  for 
electrical  apparatus,  safety  plugs  for  boilers,  dental  amalgams, 
and  for  automatic  sprinklers.  Several  compounds  of  bismuth 
are  of  value  in  medicine  and  chemistry. 

Production.  —  The  imports  for  consumption  of  metallic  bismuth 
into  the  United  States  for  several  years  have  been  as  follows: 
1912,  182,840  pounds,  value  $316,440;  1913,  117,747  pounds, 
value  $213,257;  1914,  90,505  pounds,  value  $165,208.  The 
increasing  domestic  production  is  reflected  in  the  decreasing 


WORLD'S  PRODUCTION  OF  BISMUTH 


COUNTRY 

YEAR 

POUNDS 

VALUES 

Bolivia  (ore)      •   .  • 

1913 

861,134 

774,781 

Queensland  (ore) 

1913 

205  500 

46,482 

Peru  (metal) 

1913 

55  786 

46,198 

Tasmania  (ore)         •.     :  „    .    ,    . 
New  South  Wales  (ore  and  metal)    . 
Spain  (ore)    

1913 
1913 
1912 

12,379 

19,488 
160  965 

7,917 
5,850 
1,801 

Saxony  (metal)      .       •"  i 

1912 

7  145 

12,763 

788  ECONOMIC  GEOLOGY 

imports,  it  is  claimed.  The  price  of  bismuth  in  the  United  States 
was  $2.75  per  pound  at  the  beginning  of  1915,  but  by  the  end  of 
the  year  it  had  risen  to  $4  per  pound. 

REFERENCES    ON    BISMUTH 

•1.  Dunn,  Amer.  Inst.  Min.  Engrs.,  Trans.  XLVI:  648,  1914.  (Smelter 
fumes.)  2.  Eilers,  Amer.  Inst.  Min.  Engrs.,  Trans.  XLVII:  217, 
1914.  (Rarer  metals  in  blister  copper.)  3.  Harkins  and  Swain,  Amer. 
Chem.  Soc.,  Jour.,  XXIX:  992,  1907.  (Smelter  smoke  constituents.) 
4.  Hess,  Chapters  on  Bismuth  in  Mineral  Resources  of  U.  S.  Geological 
Survey.  5.  Pittman,  Min.  Res.  New  South  Wales,  p.  256,  1901. 

CADMIUM 

The  chief  ore  mineral  of  cadmium  is  greenockite  (CdS) ,  but  no 
deposits  of  this  mineral  are  known,  and  it  is  found  chiefly  in 
association  with  sphalerite.  Greenockite  occurs  in  the  Joplin, 
Missouri,  district  as  a  greenish  yellow  coating  on  sphalerite, 
being  a  secondary  deposit  which  has  been  caused  by  the  decom- 
position of  cadmium-bearing  blende  in  the  upper  part  of  the  ore 
body,  and  the  precipitation  of  the  sulphide  at  lower  levels.  The 
average  percentage  in  several  thousand  shipments  from  the 
Joplin  district  was  .358  per  cent.  The  table  on  page  789  gives 
the  analyses  of  a  number  cf  samples  of  Missouri  ore  and  their 
cadmium  contents. 

The  calamine  ores  from  Hanover,  New  Mexico,  also  contain 
cadmium  in  sufficient  quantity  to  give  a  yellow  tint  to  the  zinc 
oxide  made  from  them. 

Cadmium  has  been  obtained  from  zinc  ores  in  the  United 
States,  but  at  present  most  of  the  output  is  said  to  be  gained 
from  bag-house  fumes  of  lead  smelters  which  treat  lead  ores 
containing  more  or  less  zinc. 

The  Silesia  zinc  regions  are  the  chief  source  of  supply,  the 
cadmium  being  obtained  as  a  by-product  in  the  distillation  of 
zinc. 

The  domestic  production  has  varied,  and  is  not  published. 
The  imports  in  1913  amounted  to  1656  pounds,  valued  at  $1232, 
and  in  1914  to  441  pounds,  valued  at  $368. 

Uses  of  Cadmium.  • —  Cadmium  is  used  chiefly  by  manufac- 
turers of  silverware,  since  the  addition  of  only  .5  per  cent  imparts 
malleability  to  the  alloy  and  prevents  the  formation  of  blisters. 
While  cadmium,  like  bismuth,  reduces  the  melting-point  of  the 


MINOR    METALS 


789 


ANALYSIS  OF  CADMIFEROUS  ZINC  BLENDES 
(W.  George  Waring,  analyst.) 


ORE 

ZINC 

IRON 

LEAD 

COPPER 

CADMIUM 

Sphinx      mine,      Neck 

City  Mo 

65.77 

0.55 

0.00 

0.077 

0.135 

Ore  from  Golconda,  111. 

60.55 

1.18 

.51 

.046 

.110 

Standard     mine,      For- 

tuna  jVto 

61.97 

.55 

.815 

.133 

.436 

Maude  B.  mine,  Webb 

City,  Mo.     .... 

55.70 

4.90 

Trace 

Trace 

.227 

Big    Six  mine,  Aurora, 

Mo 

56.75 

1.88 

None 

.004 

.018 

McKinley   mine,    Pros- 
perity, Mo.    .     .     ./  !. 

57.20 

1.25 

5.29 

None 

.550 

Hudson  mine,  Pleasant 

Valley,  Mo.       .     .     . 

62.05 

.61 

None 

.030 

.322 

Underwriters'         mine, 

— 

W^ebb  City,  Mo.   .     . 

57.95 

1.60 

1.62 

.710 

Blende  from  Kentucky 

fluorspar  mines      .     . 

53.50 

.77 

.76 

None 

.211 

Average    of    2270    car- 

loads     from      Webb 

City,  Mo.,  1902    .     . 

57.08 

2.60 

.90 

.050 

.337 

Average   percentage   of 

cadmium    in    10,906 

shipments,        mostly 

carload  lots       .     .     . 

— 

— 

— 

— 

.358 

alloys  into  which  it  enters,  it  also  produces  more  malleable  and 
ductile  ones  in  most  cases,  gold,  platinum,  and  copper  being 
exceptions.  Dental  amalgam  has  26  per  cent  cadmium  and  74 
per  cent  mercury.  The  salts  of  cadmium  are  used  in  dentistry, 
dyeing,  glass  making,  photography,  and  pyrotechnics. 

REFERENCES  ON  CADMIUM 

1.  Siebenthal,  U.  S.  Geol.  Surv.,  Min.  Res.,  1908.  (General.)  Also  Ibid., 
Bull.  606,  1916.  2.  Branner,  Ark.  Geol.  Surv.,  Ann.  Kept.,  1892,  V, 
1900. 

CHROMIC   IRON  ORE 


Ore  Minerals.  —  Chromite  (FeO,  C^Oa)  is  the  chief  source 
of  the  compounds  of  the  metal  chromium  which  are  used  in  the 
arts.  This  mineral  occurs  in  basic  rocks  like  peridotites  or  in 
the  serpentines  derived  from  them. 

The   chromite   may  occur   as  disseminated    grains,   irregular 


790 


ECONOMIC   GEOLOGY 


bunches,  or  in  stringers,  and  is  usually  a  product  of  magmatic 
segregation.  In  most  cases  the  igneous  rock  is  almost  completely 
serpentinized. 

Analyses.  —  The   following    table   gives    the    composition   of 
several  of  the  types  of  chromic  iron  ores :  — 


COLERAINE, 

FRANCE 

CAN., 

Concentrated 

ASIA 
MINOR 

STYRIA 

CALIF. 

RUSSIA 

Product 

Cr203     .     . 

37.00 

53.64 

53.00 

53.00 

42.20 

59.00 

SiO2.     .j  V 

2.53 

2.31 

2.15 

2.50 

5.48 

2.20 

A12O3     *    . 

13.15 

14.02 

7.62 

8.00 

13.60 

10.00 

MgO      .     .' 
FeO  .     .    „ 

12.53 
34.79 

15.75 
11.47 

13.31 
24.92 

11.58 
24.92 

14.88 
23.84 

11.62 

18.18 

CaO  .     ,  .  .- 

— 

2.81 

—  • 

The  price  of  chromic   iron   ore  is  based  on  its  percentage  of 
chromic  oxide,  the  standard  ore  containing  50  per  cent.     Every 


122°30' 


X  Chromite  locality 

5?  Brawn's  chromite  mine 

FIG.  279.  —  Map  showing  chromic  iron  ore  localities  in  Shasta  County,  Calif. 

(After  Diller.) 

unit  above  this  is  usually  valued  at  from  50  to  60  cents  per  ton; 
but  when  the  percentage  is  below  50  per  cent,  the  value  decreases 
at  an  even  greater  rate.  However,  ores  carrying  only  45  per 


MINOR  METALS 


791 


NW. 


SE. 


cent  of  chromic  oxide  are  easily  marketable.  Low  silica  is  desir- 
able. The  silica  permissible  in  50  per  cent  ore  is  8  per  cent. 
In  1915,  owing  to  the  war,  prices  of  imported  50  per  cent  ore 
rose  to  $25  to  $35  per  ton  in  large  lots.  California  ore  ranged 
from  $11  to  $18  per  ton  f.o.b. 

Distribution  of  Chromite  in  the  United  States  (8).  —  Chromite 
mining  is  an  industry  of  very  little  importance  in  the  United 
States,  because  the  deposits,  though  widespread,  are  rarely  of 
workable  size.  Deposits  are  known  in  Maryland,  Pennsylvania 
(11,  12),  North  Carolina  (7),  Wyoming  and  California  (4,  5). 

The  ore  was  at  one  time  obtained  from  Chester  and  Delaware 
counties,  Pennsylvania,  and  Baltimore  County,  Maryland,  but 
these  are  no  longer  worked.  Chromite  sand  is,  however,  obtained 
from  stream  deposits  within  the  chromiferous  serpentine  area  of 
Maryland. 

California    (4,   5)    contains   a   number     of    chromic    iron    ore 
deposits,  scattered  through  the  serpentine  and  closely  related 
intrusive  rocks  of  the  Coast 
Range  and  the  Sierra  Nevada, 
but  the  production  from  these 
is  usually  small,  as  the  trans- 
continental       transportation 
problem  is  a  serious  one. 

The  deposits  of  Shasta 
County  (Fig.  279) ,  which  have 
in  recent  years  attracted  the 
most  attention,  occur  in  a 
mass  of  serpentine  and  allied 
recks.  In  one  of  these  (Fig. 
280)  an  ore  body  about  25 
feet  wide  and  100  feet  long  is 
found. 

Canada  (3,  2).- — The  Canadian  production  is  generally 
small.  Deposits  are  known  to  occur  in  the  serpentine  rocks  of 
the  Quebec  asbestos  area  (see  p.  302),  where  they  form  irregular 
or  lens-shaped  bodies  of  workable  size,  and  also  nodules  and 
grains  disseminated  through  the  serpentine  and  pyroxenite. 

Alaska  (l).  —  Chromic  iron  ore  is  said  to  occur  as  a  lode 
deposit  near  Port  Chatham  on  Kenai  Peninsula,  and  chromite 
fragments  have  also  been  found  in  the  gold  placers  of  Shungnak 
in  the  upper  Kobuk  basin. 


FIG.  280.  —  Section  of  Brown's  chromic 
iron  ore  mine,  Shasta  County,  Calif. 
a.  Pyroxenite,  in  some  places  saxonite 
or  dunite;  6,  lean  ore  granular  groups- 
of  chromite  in  pyroxene  and  olivine; 
c,  ore  richer  in  chromite,  pyroxene, 
and  olivine  (?)  altered  to  chlorite  and 
chromic  chlorite.  (After  Diller.) 


792  ECONOMIC   GEOLOGY 

Other  Foreign  Deposits.1 — The  principal  foreign  sources  of  chromite, 
and  of  the  world  are  New  Caledonia,  Rhodesia,  Turkey  in  Asia,  and  Greece, 
but  during  the  war  most  of  these  have  been  practically  closed  to  the  United 
States. 

New  Caledonia.  —  The  ore  in  the  southern  part  of  the  island  occurs  as 
rich,  soft,  masses  in  ferruginous  clay,  and  as  veins  and  irregular  masses  in 
serpentine.  That  found  in  the  northern  part  of  the  island  is  more  important, 
and  may  run  67  per  cent  Cr2O3. 

Rhodesia.  —  This  is  an  important  producer.  The  ore  occurs  in  talc 
schist  and  serpentine,  usually  as  disseminations,  but  at  times  forming  mass- 
ive lenses  which  range  from  150  to  450  feet  in  length.2 

Turkey.  —  In  Turkey  in  Asia,  the  chromite  ore  occurs  in  serpentine, 
while  that  of  Greece  is  associated  with  both  basic  rocks  and  limestone. 

Interesting  but  not  very  important  deposits  are  found  in  Norway,  at 
Mount  Dun  in  New  Zealand,  and  at  Kraubat  in  Styria  (Fig.  135). 3  Some 
is  also  found  in  the  Cuban  iron  ore  deposits. 

Uses.  —  Metallic  chromium  has  no  direct  use ;  but  raw  chromite 
and  chromium  salts  have  a  variety  of  applications.  Owing  to  its 
great  heat-resisting  qualities,  chromite  is  employed  in  the  manufac- 
ture of  refractory  bricks.  Such  bricks  are  sometimes  used  for  lining 
basic  open-hearth  furnaces,  and  as  a  hearth  lining  for  water-jacket 
furnaces  in  copper  smelting.  They  stand  rapid  changes  of  tempera- 
ture well,  and  are  not  attacked  by  molten  metals. 

In  the  presence  of  carbon,  chromium  makes  steel  extremely  hard 
and  resistant  to  shocks ;  therefore  chrome  steel  is  suited  to  a  variety 
of  uses,  as  in  the  manufacture  of  plates,  hard-edged  tools,  etc.  An 
alloy  of  iron  and  chromium  is  used  in  armor  plates,  alloys  of  ferro- 
chromium  and  ferronickel  being  added  to  the  molten  steel  before 
casting.  Most  of  the  chromite  mined  is  used  for  pigments  because 
of  the  red,  yellow,  and  green  color  of  its  compounds,  chromate  and 
bichromate  of  potash.  In  these  forms  the  substance  is  employed 
in  dyeing,  calico  printing,  and  the  making  of  pigments  useful  in 
painting,  printing  wall  papers,  and  coloring  pottery.  Alkali  no 
bichromates  are  employed  for  tanning  skins,  and  some  chromium 
salts  have  a  medicinal  value. 

Production  of  Chromite.  —  The  amount  of  chromite  produced 
in  the  United  States  is  small,  and  California  has  usually  been 
the  only  source  of  supply,  although  Wyoming  produced  a  small 
amount  in  1908  and  1909,  and  Maryland  in  1914.  The  United 

1  Bull.  Imp.  Inst.,  VIII,  Nos.  3  and  4,  1910. 

2  Min.  Mag.,  Feb.,  1915. 

*  Vogt,  Krusch  and  Beyschlag,  translation  by  Truscott,  I  :  244,  1914. 


MINOR  METALS  793 

States  production  in  1914  was  591  long  tons,  valued  at  $8715, 
or  $14.75  per  ton,  but  in  1915,  owing  to  war  conditions,  it  rose 
to  3281  long  tons,  valued  at  $36,744. 

The  world's  production  in  part,  is  as  follows:  New  Cale- 
donia (1913),  62,352  long  tons;  Rhodesia  (1913),  62,365  long 
tons;  Russia  (1912),  20,934  long  tons. 

The  imports  into  the  United  States  in  1914  were  as  follows: 
Chromic  iron  ore,  80,736  long  tons,  value  $695,645;  chromic 
acid,  9164  pounds,  value  $1597;  chromate  and  bichromate  of 
potash,  31,858  pounds,  value  $2375. 

Canada  in  1914  produced  136  short  tons  of  chromite,  valued 
at  $1210,  but  in  1915  the  production  amounted  to  14,291  short 
tons,  valued  at  $208,718,  ore  averaging  from  30  to  35  per  cent 
finding  a  ready  market. 

REFERENCES    ON    CHROMIC    IRON    ORE 

1.  Brooks,  U,  S.  Geol.  Surv.,  Bull.  592  :  36,  1914.  (Alaska.)  2.  Camsell, 
Can.  Geol.  Surv.,  Mem.  26  :  56,  1913.  (B.  C.)  3.  Cirkel,  Can. 
Dept.  Mines,  Mines  Branch,  No.  29,  1909.  (Quebec.)  4.  Diller, 
U.  S.  Geol.  Surv.,  Min.  Res.,  1914  and  1915.  (Calif.)  5.  Dolbear, 
Min.  and  Sci.  Pr.,  CX  :  356,  1915.  (Calif.)  6.  Maynard,  Amer. 
Inst.  Min.  Engrs.,  XXVII:  283,  1898.  (N.  F.)  7.  Pratt  and  Lewis, 
N.  Ca.  Geol.  Surv.,  I:  269,  1905.  (Origin.)  8.  Harder,  U.  S.  Geol. 
Surv.,  Min.  Res.,  1908.  (U.  S.)  9.  Anon.,  Cal.  State  Ming.  Bur., 
Bull.  38:  266.  (Calif.)  10.  Mathews,  Md.  Geol.  Surv.,  Rept.  on 
Cecil  County.  (Md.)  11.  Rogers  and  others,  Second  Pa.  Geol. 
Surv.,  C  4  :  92.  (Chester  Co.)  12.  Hall,  Second  Pa.  Geol.  Surv., 
C  5.  (Delaware  Co.)  13.  Emerson,  U.  S.  Geol.  Surv.,  Atlas  Fol.  50, 
1898.  (Chester,  Mass.)  14.  Dresser,  Can.  Geol.  Surv.,  Mem.  22  (Que.) 


MOLYBDENUM 

Ores  and  Occurrences.  —  Molybdenite  (MoS2)  and,  less  com- 
monly, wulfenite  (PbMoC^)  are  the  chief  sources  of  this  metal. 

Molybdenite  may  occur  as  a  constituent  of  pegmatite  veins; 
it  also  forms  irregular  masses  or  disseminations  in  crystalline 
rocks,  and  many  occurrences  are  known  in  the  West,  for  example, 
in  California,  Washington,  Montana,  Utah,  Arizona,  New  Mexico, 
and  in  the  East,  in  Maine  (4) .  Wulfenite  is  found  in  the  oxidized 
zone  of  lead  ores  in  a  number  of  western  states.  Numerous 
references  to  different  occurrences  are  found  in  the  Mineral 
Resources  issued  by  the  United  States  Geological  Survey. 


794  ECONOMIC  GEOLOGY 

Several  occurrences  have  been  described  from  Quebec  and 
Nova  Scotia  (7). 

Marketable  molybdenum  ores  should  carry  at  least  25  per 
cent  molybdenum  oxide  and  be  free  from  copper,  vanadium, 
tungsten  and  chromium. 

Uses.  —  The  chief  use  of  molybdenum  is  in  making  "  high 
speed  "  steels,  and  this  apparently  caused  its  price  to  rise  from 
20  or  30  cents  a  pound  in  1912,  to  $2  a  pound  in  1914.  Ammo- 
nium molybdate  is  a  chemical  reagent.  Metallic  molybdenum 
is  used  in  resistance  furnaces,  as  supports  for  filaments  in  electric 
incandescent  lamps,  as  parts  of  Roentgen  ray  tubes,  and  as  one 
of  the  alloying  metals  in  stellite. 

Production  of  Molybdenum.  —  The  production  of  molybdenum 
is  small,  but  there  was  a  greater  demand  for  it  in  1914. 

REFERENCES    ON    MOLYBDENUM 

1.  Andrews,  N.  S.  W.  Geol.  Surv.,  Min.  Res.  No.  11,  1906.     (N.  S.  W.) 

2.  Cameron,  Queensland  Geol.  Surv.,  Kept.  188,  1904.     (Queensland.) 

3.  Crooks,  Bull.  Geol.  Soc.  Amer.,  XV  :  283,  1904.     (N.  Y.)     4.  Sm'th, 
U.  S.  Geol.  Surv.,  Bull.  260  :  197,   1905.     (E.  Me.)     5.  Hess,  U.  S. 
Geol.  Surv.,  Bull.  340  :  231,   1908.     (Me.,   Utah,   Calif.)     6.  Basker- 
ville,  Eng.  and  Min.  Jour.,  LXXXVI  :  1055,   1908.     7.  Walker,  Dept. 
Mines  Can.,  1911.     (Can.) 

NICKEL   AND    COBALT 

Ore  Minerals.  —  These  two  metals  can  best  be  treated  to- 
gether, for  nearly  all  the  ores  containing  the  one  are  apt  to  carry 
some  of  the  other,  and  furthermore,  in  smelting,  the  two  metals 
go  into  the  same  matte,  and  are  separated  later  in  the  refining 
process. 

The  ore  minerals  of  nickel  and  cobalt,  of  recognized  occurrences, 
together  with  their  composition  and  the  percentage  of  nickel  or 
cobalt  they  contain,  are  shewn  in  the  table  on  page  795.  Of 
these  some  occur  only  in  small  amounts  as  millerite,  pentlandite, 
genthite,  and  chloanthite. 

The  nickeliferous  pyrrhotite  is  the  most  widely  distributed 
of  the  economically  important  nickel  ore  minerals  and  may  carry 
small  amounts  of  cobalt.  It  is  also  called  magnetic  pyrites. 
The  percentage  of  nickel  ranges  from  a  trace  to  6  per  cent,  but 
an  increase  above  this  brings  it  into  pentlandite.  Millerite  is 
sometimes  found  associated  with  pyrrhotite  ores. 


MINOR   METALS 


795 


ORE 

COMPOSITION 

Ni 

Co 

Pyrrhotite  (nickeliferous) 
Millerite        .     .     .     .     . 
Pentlandite    

Genthite        .  •  .     .     . 

FeS 
NiS 
(FeNi)S 
2NiO>,  2MgO,  3SiO2,  6H2O 

0-6 
64.6 
22 
22  46 

— 

NiAS 

43  9 

Linn&ite 

(CoNi)3S4 

30  53 

21  34 

Chloanthite 

NiAs2 

28  1 

Smaltite 

CoAs, 

28  1 

Cobaltite       
Erythrite  (Cobalt  Hoom) 
Annabergite  (Nickel  bloom) 
Garnierite    '    '  •-    .     •     . 

CoS  ,  CoAs, 
Co3As,O8+8HoO 
Ni?As,O8+8H2O 

H2(NiMg)SiO4 

5-20 

35.4 
37.47 

Gersdorffite             .     •     • 

NiAsS 

35  4 

Cobalt-arsenopyrite    .;,/.£  . 
Skutterudite      .     .     .7. 

(FeCo)AsS 
CoAs3 

6-25 

88.2 

Distribution  in  the  United  States.  —  The  United  States  is  of 
little  importance  as  a  producer  of  nickel  and  cobalt  from  domestic 
ores,  and  the  known  occurrences  have  not  been  worked  for  several 
years.  At  Mine  la  Motte,  Missouri,  some  nickel  and  cobalt 
have  been  obtained  as  a  by-product  in  lead  mining.  Nickeliferous 
pyrrhotites  are  known  in  Virginia  and  Pennsylvania,  while  in 
Oregon  and  Idaho  some  nickel  and  cobalt  ores  have  been 
found. 


Missouri.  —  The  ore  at  Frederickstown,  Missouri,  is  a  mixture  of  chalco- 
pyrite,  galena,  linnaeite,  and  pyrite.  The  lead  is  removed  as  far  as  possible 
in  concentration,  and  the  iron  by  roasting  and  magnetic  separation.  The 
resulting  concentrate  is  smelted  (12). 

Eastern  Occurrences  of  Nickel.  —  The  Gap  Nickel  Mine,  Lancaster  County, 
Pennsylvania,  is  the  most  important  eastern  occurrence.  It  was  actively 
worked  from  1863  to  1880,  being  during  that  period  the  only  nickel  ore 
mined  on  this  continent.  In  1902  the  mine  was  again  operated  for  a  short 
time.  The  ore  is  pyrrhotite  associated  with  amph'.bolite,  an  altered  intrusive, 
the  whole  inclosed  by  mica-schist.  The  pyrrhotite  is  believed  to  have 
originated  by  magmatic  segregation  (9). 

Nickel  has  been  reported  from  a  number  of  localities  in  the  Piedmont 
reg'on  of  Virginia  (14),  especia'ly  in  association  with  the  pynhotite  bodies 
of  the  Floyd-Carroll-Grayson  counties  plateau  in  southwest  Virginia,  as 
well  as  at  several  other  points.  No  steady  production  has  been  made,  but 
the  locality  in  northern  Floyd  County  is  encouraging.  There  the  ore  which 
occurs  in  a  mica  gabbro  is  said  to  average  1.75  per  cent  nickel,  and  under 
1  per  cent  copper.  Cobalt  is  usually  very  low.  Nickel  minerals  have  also 
been  found  in  the  basic  magnesian  rocks  of  North  Carolina. 

Western  Occurrences.  —  Deposits  of  nickel  and  cobalt  ores  are  known  in 
Idaho  and  Oregon,  but  they  have  not  yet  assumed  importance. 


796  ECONOMIC   GEOLOGY 

The  only  production  in  1907  was  near  Prairie  City,  Grant  County,  Oregon, 
but  the  deposits  which  have  attracted  the  most  attention  from  time  to 
time  are  those  of  Piney  or  Nickel  Mountain  near  Riddles  (8),  Douglas  County, 
in  the  same  state. 

The  ore,  which  is  genthite  in  a  quartz  gangue,  occurs  as  flat-lying  deposits 
en  the  surface  of  post-Cretaceous  pre-Eocene  peridotite,  or  as  veinlets  in 
the  pei  ido  tite  and  serpentine.  The  former  deposits  occur  as  brecciated 
and  conglomeratic  masses,  and  consist  of  silica,  nickel  silicate,  ferric  oxide, 
and  serpentine  with  very  subordinate  chromite.  Prolonged  wea  hering 
in  some  cases  has  removed  the  nickel. 

It  is  th ought  that  the  genthite  represents  a  decomposition  product  of  the 
peridotite,  for  nickel  is  found  in  the  fresh  rock.  The  hydrated  nickel- 
magnesian  silicates  and  silica  formed  by  weathering  were  subsequently  in 
part  dissolved  and  carried  down  into  crevices  of  the  underlying  peridotite. 
Such  a  theory  limits  the  depth.  If  formed  by  ascending  hot  waters,  as 
some  believe,  a  greater  depth  would  be  assured. 

Nickel  occurs  in  a  great  many  blister  coppers,  and  the  quan- 
tity reported  in  various  ones  in  pounds  per  hundred  tons 
was  as  follows:  Anaconda,  Mont.,  22;  Great  Falls,  Mont., 
68;  Garfield,  Utah,  40;  Steptoe,  Nev.,  64;  Omaha,  Neb., 
944;  Mountain,  Cal.,  172;  Tacoma,  Wash.,  770;  Aguasca- 
lientes,  Mex.,  132;  Cerro  de  Pasco,  Peru,  32;  Mount  Lyell, 
Tasmania,  166. 

The  electrolytic  refining  of  these  coppers  has  yielded  consider- 
able nickel. 

Canadian  Occurrences.  • —  Canada  is  the  most  important  source 
of  the  nickel  and  cobalt  ores  in  North  America,  and  indeed 
in  the  world,  but  much  of  the  mine  production  is  shipped 
to  the  United  States  for  treatment  and  consumption.  It  is 
therefore  of  interest  to  refer  to  the  two  important  producing 
localities,  viz.,  Sudbury  and  Cobalt,  both  in  the  province  of 
Ontario. 

Sudbury,  Ontario  (2,  3,  4,  5,  8a).  —  This  district  is  the  main 
source  of  supply  for  the  nickel  used  on  this  continent  (Fig.  281). 

The  geological  formations  present  in  the  region  according  to 
Coleman  (5)  are  as  follows: 

Pleistocene.  Sand  and  clay. 

Paleozoic?  Diabase  and  granite  dikes. 

Keweenawan.  Sudbury  nickel-bearing  eruptive. 

C  Chelmsford  sandstone. 
Animikie  or  I  Onwatin  slate. 

Upper  Huronian.       ]  Onaping  tuff. 

I  Trout  Lake  conglomerate. 


MINOR  METALS 


797 


Lower  Huronian. 
Laurentian. 
Sudbury  series. 

Grenville  series. 
Keewatin. 


Conglomerate. 

Granitoid  gneiss  and  hornblende  schist. 

Chiefly    quartzite,    also    acid    and    basic    eruptives. 

Equivalent  (?)  to  Temiskaming  of  Cobalt  area. 
Quartzite,  and  fine-grained  gray  gneiss  and  schist. 
Chiefly  greenstone  and  greenstone  schists. 


SCALE  OF  MILES 


60      40       30      20      10       0 


GO 


50  0  50  KILOMETRES 

FIG.  281. —  Map  of  Cobalt — Porcupine  —  Sudbury  region.     (Ont.  Bur.  Mines.} 


798 


ECONOMIC  GEOLOGY 


Reference  to  the  section  (Fig.  283)  will  show  that  the  nickel- 
bearing  laccolith  appears  to  rest  on  ancient  crystallines  and  is 
covered  by  metamorphosed  Animikie  sediments;  that,  moreover, 


ue  Lake  M. 


Gray 

/WesthingtSnM" 

FIG.  282.  —  Geologic  map  of  Sudbury,  Ont.,  nickel  district.     (After  Coleman.') 

the  underlying  and  overlying  formations  are  bent  into  a  great 
canoe-shaped  trough  or  basin. 

The  intrusive  where  fresh  is  a  norite  on  its  outer  border  or  lower 
part,  and  passes  by  insensible  gradation  into  a  granite  on  its 
inner  edge  (Fig.  283). 


Scale  1  mile=Ji  inoh 

FIG.  283.  —  Geologic  section  of  Sudbury,  Ont.,  nickel  district.     (After  Coleman.} 

The  ore  bodies  are  found  at  or  near  the  margin  of  this  great 
laccolithic  sheet,  which  covers  over  500  square  miles. 

Coleman  believes  that  following  the  eruption  of  the  nickel- 
bearing  magma  there  was  a  long- continued  process  of  segregation, 
resulting  in  an  accumulation  of  the  more  basic  elements  of  the 


MINOR  METALS  799 

molten  mass  in  its  lower  part,  and  the  more  acid  elements  in  its 
upper  portion,  the  sulphides  sinking  into  the  depressions  of  the 
Archaean  substratum.  The  collapse  of  the  underlying  Archaean, 
due  to  the  upflow  of  the  magma  from  underneath,  is  supposed  to 
have  caused  a  sinking  of  the  overlying  rocks,  and  formation  of  the 
trough.  The  ore  bodies  occur  only  in  the  norite,  around  its 
margin,  or  in  some  of  the  dike-like  offsets. 

The  ores,  which  are  of  remarkably  uniform  character,  consist 
mainly  of  pyrrhotite,  chalcopyrite,  and  pentlandite,  and  though 
the  last  is  important,  it  is  rarely  visible  to  the  naked  eye.  Varia- 
tions in  the  proportions  of  these  three  may,  however,  occur. 
Thus,  in  the  Copper  Cliff  mine,  the  percentages  were  4.65  Cu  to 
4.46  Ni  one  year,  while  in  another  they  were  7.81  Cu  to  2.37  Ni. 

The  ore  bodies  are  sometimes  found  on  the  margin  of  the 
eruptive,  and  have  a  foot  wall  of  the  older  rocks,  but  an  ill- 
defined  hanging  wall.  These  form  irregular  sheets  dipping  to- 
wards the  synclinal  axis.  Others,  cf  irregular  shape,  are  found 
in  the  dike-like  projections  of  the  basic  edge. 

Several  theories  have  been  advanced  to  account  for  the  origin  of 
these  ore  bodies.  Coleman  and  others  believe  that  the  ore  is  of 
magmatic  origin  because  they  claim :  (1)  it  is  everywhere  associated 
with  norite,  and  grades  into  it,  (2)  the  adjoining  rocks  are  never 
spotted  with  ore,  and  separated  bodies  of  ore  are  never  inclosed 
in  them,  but  veinlets  of  ore  may  penetrate  them,  (3)  there  is  little 
evidence  of  hydrothermal  or  pneumatolytic  action,  such  as  one 
might  expect  if  the  deposits  were  other  than  magmatic  segrega- 
tions, and  (4)  the  largest  bodies  are  in  the  offsets,  which  represent 
the  lowest  portions  of  the  laccolith,  and  into  which  the  ore  would 
naturally  settle.  Barlow,  who  also  made  a  somewhat  careful 
study  of  this  district,  concurs  with  Coleman  regarding  the  origin 
of  the  ore  by  magmatic  segregation.  It  is,  of  course,  not  improb- 
able that  the  ore  bodies  have  been  rearranged  somewhat  later  by 
circulating  water. 

At  some  variance  with  these  views  are  those  expressed  by  Dick- 
son  (6).  His  theory  is  that  the  ore  occurs  as  a  cement  for  brec- 
ciated  rock  fragments  and  along  shearing  planes  which  are  of  pre- 
mineral  age,  the  ore  minerals  having  been  deposited  by  solutions 
and  by  a  process  of  replacement.  This  view  seems  to  be  confirmed 
by  the  examination  of  the  minerals  of  this  district  by  metal- 
lographic  methods,  which  show  the  following  order  of  succession: 
(1)  Magnetite,  (2)  silicate,  (3)  pyrrhotite,  (4)  pentlandite,  (5) 


800  ECONOMIC  GEOLOGY 

chalcopyrite.  And  following  a  long  line  of  investigators,  Knight 
(So)  presents  most  interesting  evidence  to  show  that  the  ores 
have  been  deposited  from  solution.  He  points  out  that  the 
graaite  floor  of  the  laccolith  is  younger  than  the  norite  because 
it  sends  dikes  into  it,  and  that  the  ore  is  found  not  only  in  the 
norite,  but  also  in  the  graywacke  and  the  granite,  and  concludes 
that  solutions  rising  along  the  granite  norite  contact  deposited 
the  ore. 

According  to  Coleman,  the  percentage  of  sulphides  in  the  ores 
varies  from  50  to  80,  while  the  nickel  contents  ranges  from  1.5  to 
5  per  cent.  The  cobalt  is  present  in  amounts  varying  from  -%-$  to 
ifa  of  the  nickel  present. 

An  analysis  of  a  high-grade  matte  gave:  NiCo,  48.82;  Cu, 
25.92;  Fe,  2.94;  S,  22.50;  Au,  .02  oz.;  Ag,  3.14  oz.;  Pt,  .13; 
Irid.,  .02;  Os,  .02;  Rh  and  Pal.,  tr. 

Cobalt,  Ontario  (10) .  —  The  silver-cobalt-nickel  veins  found 
at  this  locality  present  one  of  the  most  remarkable  series  of  ore 
deposits  found  in  recent  years,  and  have  their  analogue  only  in 
certain  foreign  occurrences.  The  district  lies  near  the  boundary  of 
the  provinces  of  Ontario  and  Quebec,  and  west  of  the  northern  end 
of  Lake  Temiskaming  (Fig.  281). 

The  ores  occur  in  mostly  well-defined  veins;  which  range  from 
less  than  an  inch  to  as  much  as  a  foot  or  more  in  thickness,  and 
occupy  narrow,  almost  vertical  fissures  or  joints,  cutting  through 
a  series  of  slightly  inclined  metamorphosed  fragmental  rocks  of 
Lower  Huronian  Age.  Some  are  also  found  in  the  diabase  and 
Keewatin,  although  these  last  two  are  never  so  productive. 

The  geological  section  at  this  locality  is  as  follows: 

Glacial  drift. 

Silurian. 

Niagara  limestone. 

Great  unconformity. 
Pre-Cambrian. 

Later  dikes  of  aplite,  diabase  and  basalt. 

Nipissing  diabase,  probably  of  Keweenawan  age. 

Cobalt  series.     Conglomerate,  greywacke,  and  other  fragmentals. 
Unconformity . 

Lorrain  granite. 

Lamprophyre  dikes.     Near  some  of  mines. 

Temiskaming  series.     Conglomerate  and  other  fragmental  rocks. 

Keewatin  complex.  Includes  basic  volcanics,  now  altered  to  schists 
and  greenstones;  also  altered  sediments  including  jaspilyte,  slates, 
and  greywacke. 


MINOR  METALS 


801 


The  veins  are  narrow,  practically  vertical  fissures  and  joint- 
like  cracks,  cutting  the  Cobalt  series.  A  few  productive  ones  are 
found  in  the  Nipissing  diabase  and  in  the  Keewatin  (Fig.  284). 
Most  of  the  ore  has  come  from  veins  or  parts  of  veins  that  origi- 
nally lay  beneath  the  sill. 

The  important  ores  are  native  silver,  smaltite,  and  cobaltite, 
but  associated  with  them  in  varying  quantities  are  niccolite, 
chloanthite,  millerite,  argentite,  dyscrasite,  pyrargyrite,  arsenopy- 
rite,  etc.  The  oxidized  zone,  which  is  usually  but  a  few  feet  in 


/&%al  Keewatin  E%%3  Cobalt  Series  I  Veins  !  Hypothetical  Veins 

I  I 


FIG.  284.  —  Generalized  vertical  section  through  the  productive  part  of  the  Cobalt 

Ont.,  area. 

The  section  shows  the  relations  of  the  Nipissing  diabase  sill  to  the  Keewatin 
and  the  Cobalt  series,  and  to  the  veins.  The  eroded  surface  is  restored  in  the 
section,  and  the  sill  is  less  regular  than  the  illustration  shows.  B  and  C  represent 
a  large  number  of  veins  that  are  in  the  fragmental  rocks,  Cobalt  series,  in  the  foot 
wall  of  the  eroded  sill;  N  represents  a  type  of  vein,  in  the  Keewatin  below  the 
eroded  sill;  L  a  vein  in  Keewatin  footwall,  but  not  extending  upward  into  the 
sill;  K  a  vein  in  the  sill  itself;  T  a  vein  in  Keewatin  hanging  wall  and  extending 
downward  into  the  sill.  (After  Miller,  Ont.  Bur.  Mines,  XIX,  Pt.  //,  1913.) 

depth,  shows  native  silver,  erythrite  (cobalt  bloom),  and  anna- 
bergite  (nickel  bloom).  Calcite  is  the  chief  gangue  mineral, 
quartz  being  much  less  common. 

W.  G.  Miller  (10),  who  has  given  more  careful  study  to  this 
region  than  any  one  else,  believes  that  the  ore  was  deposited  by 
highly  heated  impure  waters  circulating  through  cracks  and  fis- 
sures following  the  post-middle  Huronian  diabase  eruption.  The 
metals  may  have  been  brought  up  by  these  waters  from  a  great 
depth,  or  they  may  have  been  leached  out  of  the  now  folded  and 
disturbed  greenstones  and  other  Keewatin  rocks.  He  inclines 


802  ECONOMIC  GEOLOGY 

to  the  theory,  however,  that  the  diabase  magma  was  the  source  of 
both  the  cobalt-nickel  minerals  and  the  silver. 

The  cobalt  arsenides  were  probably  the  first  minerals  deposited, 
and  this  was  followed  by  a  slight  disturbance  of  the  veins,  result- 
ing in  the  formation  of  cracks  and  openings  in  which  the  silver  and 
later  minerals  were  deposited.  Veins  which  escaped  this  latter 
disturbance  contained  no  silver.  Many  of  the  veins  of  this 
district  are  fabulously  rich,  but  all  are  not  so.  As  an  example 
of  the  former,  an  open  cut  on  the  Trethewey  vein,  80  feet  long  and 
25  feet  deep,  yielded  $200,000  of  ore  from  an  8-inch  vein.  A 


FIG.  285.  —  Section  of  calcite,  and  native  silver,  the  latter  in  part  replacing  the 
former.     Cobalt,  Ont.      X30. 

shipment  of  80  tons  of  this  ore  gave  approximately:  As,  38  per 
cent;  Co,  12  per  cent;  Ni,  3.5  per  cent;  and  190,000  ounces 
silver.  Pay  was  received  only  for  the  cobalt  and  silver. 

The  veins  at  Cobalt  are  unique  among  North  American  ones, 
but  resemble  those  of  Annaberg,  Joachimsthal,  and  other  locali- 
ties, referred  to  below. 

The  discovery  of  these  deposits  was  made  in  building  the  Temiskaming  and 
Northern  Ontario  railroad,  and  their  development  has  made  Ontario  one  of  the 
leading  silver  producers  of  the  world.  Moreover,  it  practically  controls  the 
world's  supply  of  cobalt,  and  the  arsenic  shipped  from  the  Cobalt  camp 
equals  about  one-half  of  the  world's  production,  but  much  of  it  is  not  saved. 

Milling  plants  have  recently  been  installed  for  concentrating  the  lower  grade 
ores.  The  ores  are  treated  in  part  in  the  United  States,  but  there  are  now 
plants  erected  for  this  purpose  at  Copper  Cliff,  Deloro,  and  Thorold,  Ontario. 


MINOR  METALS  803 

Other  Foreign  Deposits. —  Deposits  of  nickeliferous  pyrrhotite  in  basic 
eruptive  rocks  are  known  at  a  number  of  localities  in  Norway,  the  ore 
averaging  1.5  to  2.5  per  cent  nickel.1  Deposits  of  a  similar  type  are 
known  in  Italy,  Spain,  and  Russia,  but  they  are  of  little  economic  im- 
portance. 

Next  to  Sudbury,  New  Caledonia  is  the  most  important  source  of  nickel 
in  the  world.2  The  island  consists  of  ancient  schists  and  Mesozoic  sedi- 
ments, pierced  by  eruptives,  especially  peridotite.  The  latter  is  more  or 
less  altered  to  serpentine.  The  ore  minerals  are  hydrated  silicates,  chiefly 
garnierite.  They  occur  as  veinlets  and  concretionary  masses  in  the  ser- 
pentine and  peridotite.  There  are  also  green  siliceous  masses  carrying  9  to 
10  per  cent  nickel.  Most  of  the  ore  is  low-grade,  averaging  7  per  cent 
nickel  after  drying  at  100°  C. 

Deposits  of  cobalt-silver  ore  similar  to  those  of  Cobalt,  Ont.,  are  found  in 
Germany  and  Austria,  viz.,  Joachimsthal  and  Annaberg.  The  ores  of  these 
two  districts  include  compounds  of  cobalt,  nickel,  bismuth,  and  silver,  and 
in  addition  uranium,  which  has  not  been  found  in  the  deposits  of  Cobalt, 
Ontario. 

At  Joachimsthal,  Bohemia,  there  is  a  series  of  mica  schists,  calc  schists, 
and  limestones  cut  by  dikes  of  basalt.  The  veins,  which  antedate  the 
basalt,  but  cut  the  other  rocks,  are  narrow,  often  brecciated,  and  contain 
hornstone,  quartz,  calcite,  and  dolomite  as  gangue  material.  Various  silver, 
nickel,  cobalt,  bismuth,  and  arsenic  minerals  are  present,  as  well  as  lead, 
zinc,  iron,  and  copper  sulphides,  together  with  uraninite.3  The  cobalt  and 
nickel  ores  are  generally  the  older,  and  the  silver  ones  younger. 

At  Annaberg,  Saxony,  the  veins  occur  in  gray  gneiss.  There  are  two 
groups,  the  younger  and  most  important  carrying  silver-cobalt  ores,  with 
nickel  and  bismuth  in  a  gangue  chiefly  of  barite,  fluorite,  quartz,  and  brown 
spar.  The  older  veins  carry  tin  and  lead. 

The  veins  at  Schneeberg,  Saxony,4  occur  in  contact-metamorphic  clay 
slates,  but  become  poorer  on  passing  into  the  underlying  granite. 

The  ore  minerals  are  smaltite,  chloanthite,  niccolite,  bismuthinite,  and 
native  bismuth  in  a  gangue  of  quartz,  hornstone,  calcite,  and  dolomite. 
Silver  minerals  are  rare. 

New  South  Wales  was  formerly  the  second  largest  world's  producer  of 
cobalt.5 

Uses  of  Nickel.  — The  most  important  and  increasing  use  of 
nickel  is  for  the  manufacture  of  nickel  and  nickel  chromium 
steel.  This,  on  account  of  its  great  hardness,  strength,  and 

1  Vogt,   Krusch  and  Beyschlag,  Translation,  I. 

2  Glasser,  Ann.  de  Mines,  15th  ser.,Tome  IV;  299  and  397,  1903;  Colvocoresses, 
Eng.  and  Min.  Jour.,  LXXXIV:   522,  1907. 

3  Vogt,  Krusch  und  Beyschlag,  Lagerstatten,  II:  173,  1912.     Also  Miller,  Ont., 
Bur.  Mines,  XIX,  Ft.  II:  213,  1913. 

4  Vogt,  Krusch  und  Beyschlag,  Lagerstatten,  II:    173, 1912;   Dalmer,  Kohler, 
and  MuHer,  Section  Schneeberg,  Geol.  Spez.  Karte  Sachsen,  1883. 

5  Pittman,  Mineral  Resources,  New  South  Wales,  N.  S.  W.  Geol.,  Surv.  1901. 


804  ECONOMIC  GEOLOGY 

elasticity,  is  used  for  making  armor  plate,  gun  shields,  turrets, 
ammunition,  hoists,  etc.  Krupp  steel,  which  may  be  taken  as  a 
type,  has  approximately  3.5  per  cent  nickel,  1.5  per  cent  chromium, 
and  .25  per  cent  carbon.  Owing  to  its  abrasive  resistance,  nickel 
steel  is  now  much  used  for  rails.  Other  important  uses  are  for 
large  forgings,  marine  engines,  wire  cables,  and  electrical  appara- 
tus. A  steel  with  25  to  30  per  cent  nickel  shows  high  resistance 
to  corrosion  by  salt,  fresh  or  acid  waters,  or  by  superheated  steam. 
German  silver  is  an  alloy  of  zinc,  copper,  and  nickel.  Monel 
metal  is  an  alloy  containing  68  per  cent  nickel,  1.5  per  cent  iron, 
and  30.5  per  cent  copper. 

Uses  of  Cobalt.  —  Cobalt  steel,  while  having  a  high  elastic 
limit  and  breaking  strength,  cannot  compete  with  nickel  steel 
on  account  of  its  high  cost,  and  the  main  use  for  cobalt  is  as  a 
pigment,  it  being  used  to  color  glass  and  pottery.  Stellite  is  an 
alloy  of  cobalt,  chromium  and  other  metals. 

Nickel  ores  were  not  mined  in  the  United  States  in  either  1913 
or  1914,  but  in  the  latter  year  the  equivalent  of  845,334  pounds  of 
metallic  nickel,  valued  at  $313,000,  is  said  to  have  been  saved  as 
a  by-product  in  the  electrolytic  refining  of  copper.  Probably 
one-third  to  one-half  of  this  came  from  domestic  ore. 

The  United  States  is  the  largest  nickel  refining  country  of  the 
world,  most  of  the  metal  being  derived  from  Canadian  matte,  and 
sorre  indirectly  from  New  Caledonia.  The  total  imports  of  nickel 
alloys,  pigs,  etc.,  ore  and  matte  (nickel  content),  and  nickel  oxide 
imported  into  the  United  States  in  1914  amounted  to  35,098,958 
pounds,  valued  at  $5,000,594.  The  exports  of  nickel  and  nickel 
oxides  from  the  United  States  in  1914  amounted  to  27,595,152 
pounds,  valued  at  $9,455,528. 

Canada  in  1914  produced  46,396  short  tons  of  matte,  valued 
at  $7,189,031  and  containing  28,895,825  pounds  of  copper,  and 
45,517,937  pounds  of  nickel.  There  is  also  a  small  recovery  of 
nickel  in  the  form  of  nickel  oxide  from  the  Cobalt  district  ores, 
the  production  in  1914  being  reported  as  391,312  pounds  of  oxide 
valued  at  $26,483. 

The  exports  in  1914  amounted  to  46,538,327  pounds  of  nickel 
in  matte. 

Production  of  Cobalt.  —  No  cobalt  was  produced  in  the  United 
States  in  1914.  The  imports  into  the  United  States  of  cobalt 
oxide,  cobalt  ore,  and  zaffer  (an  impure  cobalt  oxide),  amounted 
to  334,556  pounds,  valued  at  $274,538. 


MINOR  METALS  805 

REFERENCES   ON   NICKEL  AND    COBALT 

1.  Barlow,  Can.  Geol.  Surv.,  Ann.  Kept.  XIV,  Pt.  H,   1904.     (Ontario.) 

2.  Barlow,  Econ.   Geol.,   I:    454,   545,   1906.     (Sudbury.)     3.  Browne, 
Econ.    Geol.,    I:    467,    1906.     (Sudbury.)     4.  Campbell    and    Knight, 
Econ.  Geol.,  II:    351,   1907.     (Microstructure  of  nickeliferous  pyrrho- 
tites.)     5.  Coleman,  Can.  Dept.  Mines.,  Mines  Branch,  No.  170,  1913. 
(Nickel   Industry.     Also   Ont.    Bur.    Mines,   Ann.   Kept.   XIV,    Pt.   3. 
(Sudbury.)     6.  Dickson,    Amer.    Inst.    Min.    Engrs.,    Trans.    XXXIV: 

3,  1904.      (Ontario.)      7.    Hodges,    Amer.    Inst,  Min.    Engrs.,    Trans. 
XIII:     657,    1885.     (Mex.)     7a.  Kalmus,    Can.    Dept.    Mines,    Mines 
Branch,  No.  309,  1914.     (Properties  of  cobalt.)     8.  Kay,  U.  S.  Geol. 
Surv.,    Bull.    315:     120,    1907.     (Ore.)     80.  Knight,    Eng.    and    Min. 
Jour.,  CI:  811,  1916.     (Sudbury.)     9.  Kemp,  Amer.  Inst.  Min.  Engrs., 
Trans.  XXIV:    620,  1895.     (Pa.)     10.  Miller,  Ont.  Bur.  Mines,  XIX, 
Pt.    II,    1913.     (Cobalt,    Ont.)     11.  Neill,    Amer.    Inst.    Min    Engrs., 
Trans.  XIII:    634,  1885.     (Mo.)      12.  See   annual  reports  on  Mineral 
Resources,  U.  S.  Geological  Survey.     13.     Umpleby,  U.  S.  Geol.  Surv., 
Bull.  528,  1913.     (Lemhi  County,  Ido.)     14.  Watson,  Min.  Res.  Va., 
1907:  578.     (Va.) 

PLATINUM  GROUP  OF  METALS 

Platinum.  —  The  ore  minerals  of  platinum  are  native  platinum 
(100  per  cent  Pt)  and  sperrylite,  PtAS2  (56.5  per  cent  Pt).  The 
former  is  commonly  found  in  placer  deposits,  but  its  original 
occurrence  is  in  associations  with  chromite  in  peridotite,  or  in 
serpentine  derived  from  it,  although  such  deposits  are  nowhere 
found  in  workable  quantity.  Sperrylite  never  occurs  in  large 
quantities,  but  is  found  in  association  with  sulphide  minerals  in 
basic  igneous  rocks  such  as  gabbro  and  diabase.  Where  occur- 
ring in  igneous  rocks  it  represents  a  crystallization  product  of 
the  magma. 

In  addition  to  these  two  types  of  occurrence  platinum  has  also 
been  found  in  quartz  veins  as  in  Nevada  (p.  806),  Canada,1 
Finland 1  and  New  Zealand,  and  also  in  at  least  one  case 
(Sumatra)  in  a  contact-metamorphic  deposit.  Iridosmine  and 
osmiridium  are  also  known  to  carry  platinum,  and  it  also  occurs 
as  an  alloy  with  other  members  of  the  platinum  group. 

Most  of  the  world's  supply  of  platinum  is  obtained  from 
placer  deposits. 

The  nuggets  found  in  placers  are  commonly  regarded  as  being 
pure  native  platinum,  but  this,  according  to  Kemp  (5),  is  only 
true  in  part,  most  of  those  assayed  yielding  between  70  and  85 

,  Econ.  Geol.  I:   749,  1906. 


806  ECONOMIC  GEOLOGY 

per  cent,  and  the  richest  recorded  being  86.5  per  cent.  The 
balance  is  made  up  largely  of  iron,  the  highest  percentage  of  this 
noted  being  19.5  per  cent  in  a  Ural  specimen.  Iridium,  rhodium, 
and  palladium  are  always  present.  Until  the  platinum  falls 
below  60  per  cent  the  iridium  rarely  reaches  5  per  cent,  rhodium 
4  per  cent,  while  palladium  is  less  than  2  per  cent.  Other  ele- 
ments that  have  been  detected  in  the  nuggets  are  osmium, 
ruthenium,  copper,  and  even  gold,  while  chromite  is  a  common 
associated  mineral  (5). 

Distribution  in  the  United  States.  —  The  domestic  supply  of 
platinum,  never  large,  is  obtained  from  gold-placer  deposits  in 
Oregon  and  California,  and  while  its  occurrence  has  been  reported 
in  many  other  gold  placers  of  the  Northwest  and  Alaska,  still  none 
of  them  have  proven  sufficiently  rich  to  work.  Most  of  the  Cali- 
fornia production  comes  from  the  dredges  at  Oroville,  in  Butte 
County.  The  platinum  is  usually  panned  from  the  black  sand, 
but  a  small  quantity  is  entangled  with  the  amalgamated  gold 
and  recovered  in  refining  at  the  mint.  Iridosmine  and  a  natural 
alloy  of  iron  and  nickel  called  josephinite  are  found  associated 
with  the  gold. 

In  addition  to  the  above  sources,  platinum  is  also  found  in  the 
copper  ores  of  the  Rambler  mine,  Wyoming,  and  has  been  saved 
from  the  slimes  obtained  in  treating  the  copper  ore  and  matte  at 
this  locality.  The  covellite  in  the  ore  is  said  to  assay  .06  to  1.4 
ounces  per  ton  of  platinum. 

A  remarkable  find  of  platinum  and  palladium  was  made  in 
1914,  in  the  Yellow  Pine  mining  district  of  Clark  County,  Nev. 
(6).  According  to  Knopf  the  deposit  consists  of  a  fine-grained 
quartz  mass,  irregularly  replacing  Carboniferous  limestone 
along  a  series  of  vertical  fractures.  A  dike  of  granite  porphyry 
is  found  not  far  from  the  ore  body,  but  no  basic  intrusives  are 
known  in  the  district.  The  ore  bodies  developed  are  oxidized 
copper  shoots  and  gold-platinum-palladium  shoots,  the  latter 
consisting  of  a  fine-grained  quart zose  ore  containing  a  small 
amount  of  a  bismuth-bearing  variety  of  plumbojarosite  (6). 
The  ore  averaged  in  ounces  per  ton:  gold,  3.46;  silver,  6.4; 
platinum,  .70;  and  palladium,  3.38.  The  deposit  differs  greatly 
from  any  known  deposit  carrying  platinum  metals,  and  is  further 
remarkable  because  of  its  probable  genetic  connection  with  acid 
igneous  rocks.  Moreover  the  lode  is  one  of  the  few  primary 
deposits  in  which  platinum  metals  occur  in  more  than  traces. 


MINOR  METALS 


807 


Canada.  —  In  the  nickel  deposits  of  Sudbury,  Ontario  (p.  796), 
platinum  arsenide,  accompanied  by  palladium  probably  also  as 
arsenide,  is  found,  the  Bessemer  mattes  carrying  from  .17  to  .5 
ounce  of  the  platinum  metals.  Platinum  has  also  been  found 
in  the  dunites  of  the  Tulameen  district,  British  Columbia,  but 
not  in  commercial  quantities. 

Other  Foreign  Deposits.  —  The  platinum  placers  of  the  Urals  in  Russia 
form  the  most  important  source  of  the  world's  supply,  the  two  principal 
centers  of  production  being  Blagodat  on  the  Asiatic  slope,  and  Nizhni- 
Tagilsk,  on  the  European  slope.1  Second  in  importance  is  Colombia, 
where  placers  are  worked  along  the  Choco  and  its  tributaries.  Like  the 
Russian  placers,  the  platinum  is  obtained  in  greater  proportion  than  gold.2 

Uses.  —  Platinum  was  first  used  as  an  adulterant  of  gold,  and 
in  Russia  it  was  used  for  coinage  from  1823  to  1845.  At  the 
present  time  it  is  employed  for  crucibles  and  other  chemical 
apparatus  which  are  to  be  subjected  to  high  temperatures  or 
strong  acids.  It  is  also  of  value  in  dentistry,  for  electric  lamps 
and  electric  apparatus,  for  jewelry,  and  in  photography.  An 
important  use  is  as  a  catalyzer  in  what  is  technically  known  as 
"  contact  mass  "  in  the  manufacture  of  fuming  sulphuric  acid 
and  sulphur  trioxide.  The  price  of  it  has  risen  steadily  in  recent 
years,  so  that  it  is  more  valuable  than  gold. 

Production.  —  A  considerable  output  of  platinum  is  annually 
made  in  the  United  States  from  the  refining  of  gold  and  copper 
bullion  of  both  domestic  and  foreign  origin. 

WORLD'S  PRODUCTION  OF  NEW  PLATINUM  IN  1913-1914,  BY  COUNTRIES, 

IN  TROY  OUNCES 


Country. 

1913 

1914 

1  250  000 

i  241  200 

Canada,  crude  :  

50 

1  275 

130 
ll  248 

Colombia   crude                                

15,000 

1  17  500 

United  States,  domestic  crude  
United  States,  refined  from  foreign  and  domestic  matte  and 

483 
3  1,100 

570 
2,905 

200 

5 

Total                                                       .             

268,108 

263,453 

1  Estimated. 

2  Chiefly  iridosmine. 

3  Does  not  include  refined  platinum  from  domestic  crude. 

4  Includes  small  production  in  Madagascar. 

5  No  basis  for  estimate. 


1U.  S.  Geol.  Surv.,  Min.  Res.,  1913,  Pt.  I:  451,  1914. 
2  Kimball,  Min.  and  Met.  Soc.  Amer.,  Bull.  65,  1913. 


808  ECONOMIC  GEOLOGY 

In  1914,  California  produced  463  ounces  of  crude  platinum 
(about  80  per  cent  fine),  and  Oregon  107  ounces  (about  70 
per  cent  fine),  the  total  value  of  these  being  $18,240.  The 
total  quantity  of  refined  platinum  produced  in  the  United 
States  in  1914  was  3430  ounces. 

During  1914  the  average  price  of  refined  metals  of  the  platinum 
group,  per  troy  ounce  was:  platinum,  $45;  iridium,  $65; 
iridosmine  (osmiridium),  $33;  palladium,  $44. 

The  imports  of  platinum,  both  crude  and  manufactured, 
into  the  United  States  in  1914  had  a  total  value  of  $2,908,353, 
as  compared  with  $5,040,210  in  1913,  the  decrease  being  due  to 
the  unsettled  conditions  abroad. 

Palladium.  —  This  metal  is  found  associated  with  platinum 
and  also  native  and  alloyed  with  gold  (Brazil).  It  is  of  silver- 
white  color,  ductile  and  malleable,  and  is  unaffected  by  the 
air.  Its  great  rarity  and  consequent  high  value  has  restricted  its 
use,  but  a  small  amount  is  used  for  some  mathematical  and  surgical 
instruments,  for  compensating  balance  wheels  and  hairsprings 
for  watches,  and  for  finely  graduated  scales. 

In  the  United  States  it  has  been  reported  from  the  platinum  de- 
posits of  the  Pacific  coast  and  from  the  Rambler  mine  in  Wyoming. 

Osmium.  —  This,  the  heaviest  and  most  infusible  metal  known, 
occurs  alloyed  with  platinum  and  also  with  iridium  in  iridosmine. 
In  the  United  States  small  quantities  have  been  found  in  the 
platinum  placers  of  California.  It  is  also  obtained  from  Tas- 
mania (10). 

Iridosmine  is  employed  for  pointing  pens  and  fine  tools,  while 
osmic  acid  is  used  for  staining  anatomical  preparations  in  micro- 
scopic work. 

Iridium.  —  Iridium  is  found  chiefly  in  Russia  and  California, 
alloyed  with  platinum  or  osmium.  It  is  a  lustrous,  steel-like 
metal  of  great  hardness,  and  is,  next  to  osmium,  the  most  refrac- 
tory metal  known. 

An  alloy  of  iridium  and  platinum  has  been  used  for  standard 
weights  and  measures,  and  iridium  is  also  used  in  photography. 

REFERENCES  ON  PLATINUM 

1.  Day,  U.  S.  Geol.  Surv.,  19th  Ann.  Kept.,  VI:  265,  1898.  2.  Day,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXX:  702,  1901.  (N.  Amer.)  3.  Camsell, 
Can.  Min.  Inst.,  XIII:  309,  1911.  (Tulameen,  Brit.  Col.)  4.  Donald, 
Eng.  and  Min.  Jour.,  LV:  81,  1893.  (Can.)  5.  Kemp,  Min.  Indus., 
X:  540,  1902;  and  U.  S.  Geol.  Surv.,  Bull.  193,  1902.  (General.) 


MINOR  METALS  809 

6.  Knopf,  U.  S.  Geol.  Surv.,  Bull.  620,  1915.  (Yellow  Pine  district, 
Nev.)  7.  Perrett,  Trans.  Inst.  Min.  and  Met.,  XXI:  647,  1912. 
(Russia.)  8.  Purington,  Eng.  and  Min.  Jour.,  LXXVII:  720,  1904. 
(Russia.)  9.  Day  and  Richards,  U.  S.  Geol.  Surv.,  Bull.  285:  150, 
1906.  (Platinum  in  black  sands.)  10.  Twelvetrees,  Tasmania  Dept. 
Mines,  Geol.  Surv.,  Bull.  17,  1914.  (Bald  Hill  osmiridium  field.) 


SELENIUM 

This  rare  and  little-known  element,  which  forms  not  over 
.0002  per  cent  of  the  known  rocks,  is  not  known  to  occur  in 
deposits  by  itself,  even  though  it  forms  combinations  with  a 
number  of  other  metals,  which  are  found  in  nature.  It  is  found 
in  some  gold,  silver  and  copper  ores. 

Thus  Spurr  has  called  attention  to  its  presence  in  the  gold 
ores  of  Tonopah,  Nevada,  where  it  is  found,  at  least  in  part  as 
a  silver  selenide.  It  is  associated  with  gold  in  the  Republic 
district  of  Washington  (6), 

Selenium  in  some  form  also  occurs  in  nearly  all  the  vanadium- 
bearing  sandstones  of  Colorado  and  Utah. 

Pyrite  ores  may  also  carry  it. 

The  commercial  supply  of  the  United  States,  however,  is  fur- 
nished by  the  electrolytic  copper  refineries,  as  nearly  all  blister 
copper  contains  it. 

The  1914  United  States  production,  saved  in  copper  refining, 
was  22,867  pounds,  valued  at  $34,277. 

Uses.  —  Selenium  is  used  as  a  red  colorant  of  glass,  while 
selenite  of  soda  gives  a  bright  red  color  to  enamels  used  for  cov- 
ering steel.  Owing  to  its  low  electrical  conductivity  in  the  light, 
and  higher  conductivity  in  the  dark,  selenium  wire  is  used  in 
automatically  lighting  and  extinguishing  gas  buoys. 

REFERENCES  ON  SELENIUM 

1.  Eilers,  Amer.  Inst.  Min.  Engrs.,  Trans.  XL VII:  217,  1914.  (Selenium, 
etc.,  in  blister  copper.)  2.  Gale,  U.  S.  Geol.  Surv.,  Bull.  340:  261, 
1908.  (In  U  and  V  ores.)  3.  Hess,  U.  S.  Geol.  Surv.,  Min.  Res., 
1914.  (General.)  4.  Hillebrand,  et  al.,  Amer.  Phil.  Soc.,  Proc.  VIII: 
34,  1914.  (Native  selenium,  Utah.)  5.  Joseph,  Eng.  and  Min.  Jour., 
LXVIII:  636,  1899.  (Republic,  Wash.)  6.  Lindgren  and  Bancroft,  U.  S. 
Geol.  Surv.,  Bull.  550,  148,  1914.  (Republic,  Wash.)  7.  Spurr,  U.  S. 
Geol.  Surv.,  Prof.  Pap.,  42:  92,  1905.  (Se  in  Tonopah  ores.)  8. 
Truscott,  Inst.  Min.  and  Met.,  Trans.,  X:  54,  1901.  (Redjang  Lebong, 
Sumatra.) 


810  ECONOMIC  GEOLOGY 

TANTALUM 

This  element  has  attracted  some  attention  because  of  its  use 
in  electric  lamps. 

Tantalite  (FeTa206)  and  columbite  [(Fe,  Mn)Nb202]  are  the 
only  minerals  found  in  the  United  States  from  which  tantalum 
could  be  produced.  They  occur  in  pegmatite  veins,  and  are 
said  to  be  found  in  some  abundance  in  those  of  the  Black  Hills 
of  South  Dakota.  Other  occurrences  are  near  Canyon  City, 
Colorado;  near  Spruce  Pine,  North  Carolina;  near  Amelia, 
Virginia,  etc. 

The  tantalum  market  is  now  said  to  be  supplied  mainly  by  the 
rich  mangano-tantalates  from  western  Australia  (2).  Scandi- 
navia has  also  supplied  some  (l), 

REFERENCES   ON  TANTALUM 

1.  Baskerville,  Eng.  and  Min.  Jour.,  LXXXVI:  1100,  1909.  2.  Hess, 
U.  S.  Geol.  Surv.,  Min.  Res.,  1908.  3.  Hess,  U.  S.  Geol.  Surv.,  Bull. 
380,  1909.  (S.  Dak.)  4.  Watson,  Min.  Res.  Va.,  1907:  298,  390. 
(Va.) 

TELLURIUM 

This  element  has  but  slight  commercial  value,  as  little  use  has 
been  found  for  it.  The  somewhat  widely  distributed  telluride 
of  gold  and  silver  ores  form  a  comparatively  common  source 
of  it,  but  owing  to  the  lack  of  demand,  no  attempt  is  made  to 
save  the  tellurium.  Cripple  Creek,  Colorado,  is  the  best-known 
occurrence  in  the  United  States,  the  tellurium  minerals  present 
being  sylvanite  (AuAg)Te2  and  calaverite  (AuTe2).  Tetra- 
dymite  (Bi2Te3)  is  found  at  a  number  of  localities. 

The  tellurium  of  commerce  is  all  obtained  as  a  by-product 
from  copper  ores.1 

Uses.  —  Unsuccessful  attempts  have  been  made  to  utilize 
tellurium  in  bearing  metals.  It  gives  glass  a  reddish  tint.  An 
alloy  of  aluminum,  zinc  and  tellurium  has  been  patented. 

TIN 

Ore  Minerals.  —  Cassiterite  (SnO2),  with  78.6  per  cent  metallic 
tin,  is  the  principal  ore  mineral  of  this  metal,  but  owing  to  the 
presence  of  impurities  it  rarely  shows  this  composition. 

lEilers,  Amer.  Inst.  Min.  Engrs.,  Trans.  XLVII:   217,  1914. 


MINOR  METALS  811 

Its  hardness  (6-7),  imperfect  cleavage,  non-magnetic  character, 
high  specific  gravity  (6.8-7.1),  and  brittleness  help  to  distinguish 
it  from  other  minerals  that  are  liable  to  occur  with  it.  Ilmenite 
and  magnetite  have  sometimes  been  mistaken  for  it. 

Stream  tin  is  the  name  applied  to  cassiterite  found  in  placers. 
Wood  tin  is  a  variety  of  cassiterite  having  a  fibrous  structure. 
Stannite,  or  tin  pyrites,  a  complex  sulphide  of  copper,  iron,  and 
tin,  rarely  serves  as  an  ore  mineral. 

Mode  of  Occurrence.  —  Cassiterite  may  occur  in  the  fol- 
lowing ways,  not  all  of  them  being  of  commercial  importance : 

(1)  As  an  original  constituent  of  igneous  rock;  (2)  as  veins, 
formed  under  pneumatolytic  or  hydrothermal  conditions;  (3)  as 
contact-metamorphic  deposits;  (4)  as  hot-spring  deposits;  and 
(5)  in  placers. 

Of  these  Nos.  2  and  5  are  of  commercial  importance,  the  others 
being  rarely  so. 

Cassiterite  in  Igneous  Rocks  (9).  —  Cassiterite  is  known  to 
occur  as  an  original  constituent  of  granite,  but  there  are  no 
known  magmatic  segregations  of  economic  importance.  It  may 
also  occur  as  a  primary  constituent  of  pegmatite  dikes,  asso- 
ciated with  lithium  and  phosphorus  minerals,  as  near  GafTney, 
South  Carolina  (10),  or  in  the  Black  Hills,  South  Dakota  (23). 
These  dikes  exhibit  sharp  walls,  and  there  is  no  replacement  of 
the  wall  rock  by  cassiterite. 

Contact  Metamorphic  Deposits  (9,  19). — This  type  is  known 
at  a  few  localities.  Those  of  Pitkaranta,  Finland,  show  cas- 
siterite associated  with  scheelite,  topaz  and  fluorite  in  limestone 
near  its  contact  with  granite.1 

Another  interesting  deposit  occurs  on  Lost  River,  Seward 
Peninsula,  Alaska  (15).  Here  the  invasion  of  .limestone  by 
granite  has  produced  a  contact  zone,  carrying  pyroxene,  tour- 
maline, axinite,  pageite,  ludwigite,  vesuvianite,  fluorite,  scapo- 
lite,  scheelite,  cassiterite,  magnetite,  galena  and  sphalerite. 

Other  cases  are  known  at  Schwarzenberg  and  Berggiess- 
hiibel,  Saxony,  and  the  Zeehan  district,  Tasmania  (19). 

Tin  Veins.  (9) .  —  Tin  veins  or  lodes,  carrying  usually  cas- 
siterite as  the  chief  Ore  mineral  of  this  metal,  may  evidently 
be  formed  under  different  physical  conditions. 

Pneumatolytic  Veins. —  The  commonest  type  is  that  of  pneu- 
matolytic origin  found  usually  in  granite,  or  close  proximity 

1  Vogt,  Krusch  and  Beyschlag,  Ore  Deposits,  Translation,  1 :  405. 


812 


ECONOMIC  GEOLOGY 


to  it,  and  showing  a  rather  uniform  group  of  minerals  (Fig.  286), 
the  metallic  ones  including  cassiterite,  wolframite  and  scheelite, 
arsenopyrite,  bismuth,  and  others  in  lesser  amounts,  while 
the  gangue  minerals  include  quartz  (important),  lithia  mica, 
topaz,  tourmaline,  fluorite,  etc.  Cassiterite  is  the  chief  ore 


Total  occurrences 

j 

Quartz     . 

^~~l 

Fluorite   _ 

^  1......  , 

Tourmaline.  

Wolframite    __     _ 

I 

Pyrite 

^^A 

Chalcopyrite    _ 

H^j  ^ 

Muscovite  .     _ 

^^^—  |^"   '              / 

^^~  1 

Orthoclase 

^^^^  1 

Galena  _   _ 

^  h~-l_ 

Topaz   ._     _.  __ 

TTTfr- 

.Magnetite  

V, 

Molybdenite.  

\-  p~^-^_ 

Sphalerite 

^^ 

Chlorite 

™  

Pyrrhotite  _ 

%%-^_ 

Scheelite    ._. 

Stannite 

I2 

Total  fluorine  minerals.  _. 

Total  boron  minerals  
Total  tungsten  minerals. 



FIG.  286.  —  Approximate  quantitative  distribution  of  the  more  important  min- 
erals associated  with  cassiterite.  Length  of  line  is  proportional  to  the 
number  of  occurrences.  Height  represents  relative  abundance.  J.=very 
abundant;  B=  plentiful;  C  =  prominent ;  Z>=rare;  X  =  quantity  unknown. 
(After  Ferguson  and  Bateman,  Econ.  Geol.  VII.) 

mineral,  but  the  tin  content  is  generally  low,  often  under  one 
per  cent.  The  cassiterite  frequently  occurs  in  the  wTall  rock 
on  either  side  of  the  fissures,  and  where  these  are  abundant  a 
considerable  mass  of  rock  may  be  impregnated  with  ore. 

A  characteristic  feature  of  tin  veins  is  the  metasomatic  alter- 
ation of  the  wall  rock,  resulting  in  a  coarse-grained  mixture  of 
quartz,  muscovite,  lithia  mica,  topaz  and  tourmaline,  called 
greisen.  If  tin  is  present  in  the  vein,  it  usually  occurs  in  the 


MINOR  METALS 


813 


greisen,  replacing  the  feldspar.  The  tourmaline  and  topaz  are 
not  always  equally  prominent,  and  one  or  the  other  may  be  absent. 

Greisenization  is  not  confined  to  granites,  but  may  also  be 
developed  in  shale,  slate,  limestone  and  diabase. 

The  two  following  analyses,  represent,  I,  the  fresh  granite, 
and  II,  greisen  derived  from  it. 


I 

II 

I 

II 

SiO2    

74.68 

'70.41 

NaO+LiO  

1.54 

0.98 

ALCK 

12  73 

:13  06 

KO 

4  64 

3  01 

Fe2O3 

1.42 

H2O  

1.17 

0  76 

FeO 

3  00 

5  09 

TiO2  

0  71 

0  49 

MffO 

0  35 

0  09 

SnO 

0  09 

0  49 

CaO 

0  09 

2 

A1F2  

33.91 

CuO 

0  50 

CaF2  

0  29 

99.50 

100.00 

1  After  deduction  of  part  of  Al.     2  CaO  calculated  as  CaF2.    3  Calculated  value. 

The  change  in  general  indicates  addition  of  iron,  lithium, 
tin,  fluorine  and  boron,  with  subtraction  of  lime,  potash  and  soda. 

Vogt,  Beaumont,  Daubree,  and  others  believe  that  the  tin 
veins  were  formed  immediately  after  or  even  during  granitic 
eruptions,  and  that  the  mineral  solutions  originated  by  the  action 
of  hydrofluoric  or  hydrochloric  acid  on  the  magma,  still  entirely 
or  partly  in  igneous  fusion.  These  extracted  fluorides  of  silicon, 
tin,  boron,  and  lithium  as  well  as  phosphoric  acid.  The  type 
of  alteration  of  these  pneumatolytic  emanations  varies  somewhat, 
schist  being  altered  somewhat  differently  from  granite. 

Hydrothermal  Veins.  —  These  are  represented  by  vein  types 
found  in  the  Zeehan  field  of  Tasmania,1  and  the  Cerro  de  Potosi 
district  of  Bolivia.2  At  the  former  crustified  veins  carrying 
stannite,  pyrite,  siderite,  galena,  chalcopyrite  and  some  cassiter- 
ite  are  found,  representing  a  lower-temperature  condition  of 
deposition  than  the  cassiterite  granite  veins,  and  cassiterite 
contact-metamorphic  deposits  found  in  the  same  district. 

Shallow  depth  veins  are  represented  by  those  found  in  rhyolite 
of  the  Guanajuato  district,  Mexico.3 

1  Twelvetrees  and  Ward,  Dept.  Mines,  Tasmania,  Bull.  8. 
2Singewald,  Econ.  Geol.,  VII:  272,  1912. 
3  Wittlich,  Zeitschr,  prak.  Geol.,  1910:   121. 


814 


ECONOMIC  GEOLOGY 


Hot  Spring  Deposits.  —  Tin  appears  to  be  formed  in  some 
cases  by  precipitation  at  normal  pressure  from  thermal  waters, 
for  a  stanniferous  siliceous  sinter  has  been  deposited  by  a  hot 
spring  in  Malacca.  It  contains  SiO2,  91.8;  SnC>2,  .5; 
.2;  and  H2O,  7.5  (quoted  by  Lindgren). 


Original 
Constituents. 


Pneumato-        Contact-          Hydro- 

litic.       metamorphic.     thermal.     Hot  Springs. 


Decreasing  temperature  and  pressure  — » 

FIG.  287.  —  Diagram  to  illustrate  the  genetic  distribution  and  gradation  of  some 
of  the  more  common  minerals  in  their  association  with  cassiterite  only. 
(After  Ferguson  and  Bateman,  Econ.  Geol.  VII.) 

Placer  Deposits  (8,  9). —  These  form  the  most  important 
source  of  tin  ore,  and  have  been  formed  in  the  manner  described 
on  p.  433.  Accompanying  the  cassiterite  there  may  be  wol- 
framite, and  other  heavy  minerals. 

Distribution  of  Tin  Ores  in  the  United  States  (13).  Tin  has 
been  found  at  many  localities  in  both  the  eastern  and  western 
United  States  as  well  as  in  Alaska,  but  most  of  the  deposits 
have  thus  far  proved  to  be  of  little  or  no  commercial  value. 

North  Carolina  and  South  Carolina  (10,  11).  —  In  these  two 
states  there  is  a  belt  of  tin  ore  which  extends  from  near  Gaffney, 


MINOR  METALS 


815 


Cherokee  County,  South  Carolina,  across  parts  of  Cleveland 
and  Gaston  Counties,  North  Carolina,  to  near  Lincolnton,  being 
in  all  35  miles  long.  The  cassiterite  is  irregularly  distributed 
in  pegmatite  dikes  in  schists,  the  latter  being  metamorphosed 
sediments  interstratified  with  slates,  marbles,  and  quartzites. 
Gabbro,  diabase,  and  granite  intrusions  are  also  present.  This 
belt  has  not  yet  proved  to  be  of  commercial  value  although 
some  mining  has  been  done  in  years  past,  and  a  little  ore  shipped. 


TTio.  288.  —  Sketch  map  showing  location  of  Carolina  tin  belt.     (After  Graton, 
U.  S.  Geol.  Surv.,  Bull.  260.) 

South  Dakota  and  Wyoming  (14,  23).  —  The  most  widely 
known  occurrence  of  tin  ores  in  the  United  States  is  in  the  Black 
Hills.  Tin  was  discovered  in  the  Harney  Peak  district  and  later 
in  Nigger  Hill.  The  tin  ore  (cassiterite)  occurs  as  disseminations 
in  pegmatites,  in  quartz  veins,  and  in  placers.  The  occurrences 
have  never  amounted  to  much. 

Alaska  (7,  15).  —  Tin  is  found  in  the  York  region  of  the 
Seward  Peninsula,  where  it  occurs  chiefly  in  placers  and  lodes 
and  at  a  number  of  other  places,  but  as  yet  there  has  been  little 
production.  The  lode  deposits  show  the  following  types: 
(1)  quartz  veins  cutting  phyllites  or  metamorphic  slates;  (2) 
disseminations  in  more  or  less  altered  granite  rocks;  (3)  in 
quartz  porphyry  dikes  cutting  limestone,  and  accompanied  by 
fluorite,  zinnwaldite,  etc. 


816 


ECONOMIC  GEOLOGY 


Foreign  Deposits.  —  Cassiterite  veins  are  known  in  many  parts  of  the 
world  (8).  The  Cornwall,  Eng.,  deposits,  worked  for  many  years,  show  tin 
veins  occurring  in  post-Carboniferous  granites,  and  also  in  slates  (killas) 
intruded  by  them.  An  interesting  feature  is  the  presence  of  copper  with 
little  tin  in  the  upper  parts  of  the  veins,  which  changes  to  a  straight  tin  ore 
where  the  veins  pass  from  slate  to  granite.  Not  a  little  tungsten  is  alsc 
obtained  from  some  of  the  workings. 

Another  classic  district  is  that  of  the  Erzgebirge  l  in  Saxony,  and  neigh- 
boring parts  of  Bohemia.  At  Altenberg  (Fig.  289),  the  ores  form  a  stock- 
work  of  small  veins  cutting  a  post-Carboniferous  granite  (Plate  XLI,  Fig.  2, 

and  Plate  LXXV,  Fig.  1)  and  an 
older  granite  porphyry,  the  devel  - 
opment  of  greisen  being  quite  ex- 
tensive. In  the  neighboring  Zinn- 
wald  deposits,  the  flat  veins  appear 
to  be  formed  largely  by  filling. 

Interesting  and  important  de- 
posits are  those  of  Mount  Bishoff, 
Tasmania,  where  the  schists  have 
been  cut  by  dikes  of  granite 
porphyry,  both  rocks  being  re- 
placed by  tourmaline  and  topaz, 
and  the  entire  mass  carrying  veins 
of  cassiterite.2 

Curious  because  of  their  min- 
eralogical  relations  are  the  Boliv- 
ian veins.3  The  country  rock, 
which  is  Devonian  slate,  intruded 
by  granite  porphyry  dikes,  is  ex- 
tensively tourmalinized.  Associ- 
ated with  the  cassiterite  is  stan- 
nite,  stephanite,  ruby  silver, 
tetrahedrite,  blend  3  wolframite, 
arsenopyrite,  etc. 

The  Mexican  ores  are  unique 
because  of  their  occurrence  in 
rhyolite,  but  of  little  commercial 
value. 

The  chief  source  of  the  world's 
production  is  the  Malay  Penin- 
sula, and  Banka  and  Billiton 
Islands  off  Sumatra.  The  ore 


C77C1 

1 


ES-1 
i 


EM 

7 


FIG.  289,  —  Geologic  map  of  Altenberg- 
Zinnwald  tin  district,  Saxony.  1.  Por- 
phyritic  granite;  2.  Teplitz  quartz 
porphyry;  3.  Granite  with  flat  tin 
lodes;  4.  Silicified  porphyry;  5.  Quartz 
porphyry  impregnated  with  tin  ore; 
6.  Steep  tin  lodes;  7.  Tin  gravel. 

.      (After  Vogt,  Krusch,  und  Beyschlag,  /.) 


here  is  obtained  chiefly  from 
placers.4  Tin  veins  are  also  known 
in  both  districts. 


1  Singewald,  Econ.  GeoL  V:    166  and  265,  1910. 

2  Krusch,  Zeitschr.  prak.  Geol.,  1900:  86. 

3  Rumbold,  Econ.  Geol.,  IV:   321,  1909. 

4  Penrose,  Jour.  Geol.  II:   135,  1903. 


PLATE  LXXV 


FIG.  1.  —  Old  workings  of  tin  mine,  Altenberg,  Saxony.     (H.  Ries,  photo.) 


FiG.  2.  —  Rutile  mine,  near  Roseland,  Va.     (H.  Ries,  photo.) 


(817) 


818  ECONOMIC  GEOLOGY 

Uses  of  Tin.  —  Tin  is  used  chiefly  for  the  manufacture  of 
bronze  and  tin  plate,  and  to  a  smaller  extent  in  plumbing  as  well 
as  less  important  purposes.  Britannia  metal  is  composed  of 
from  82  to  90  parts  of  tin  alloyed  with  antimony,  copper,  and 
sometimes  zinc. 

Production  of  Tin.  —  The  amount  of  tin  produced  in  the 
United  States  including  Alaska  is  entirely  too  small  to  supply 
the  demand,  and  the  main  source  of  supply  for  this  country, 
and  indeed  for  the  world,  is  the  Malay  peninsula,  while  other 
regions  of  commercial  importance  are  Australia  and  Bolivia. 
The  available  figures  are  given  below. 

The  tin  ore  produced  in  Alaska  in  1914  amounted  to  157.5 
tons  of  concentrates,  carrying  104  tons  of  tin,  worth  $66,560. 
The  only  tin  produced  in  the  United  States  came  from  near 
Tinton,  S.  Dak. 

The  tin  imported  into  the  United  States  in  1914  amounted 
to  52,919  short  tons,  valued  at  $32,943,059. 

WORLD'S  PRODUCTION  OF  TIN  IN  1914,  IN  SHORT  TONS 

London  deliveries 23,335 

Continent  of  Europe 22,747 

Cornwall  (production) 6,720 

Bolivia  (shipments) 21,000 

South  Africa  (shipments) 5,600 

China  (shipments) 2,128 

United  States  (receipts) 48,505 


Total 130,035 

Deductions  of  Straits,  etc.,  from  continent  and  English, 

Bolivia,  etc.,  Arriving  in  United  States 9,635 


Total 120,400 

REFERENCES  ON  TIN 

1.  Blake,  Amer.  Inst.  Min.  Engrs.,  Trans.  XIII:  691.  (Black  Hills.) 
2.  Blake,  U.  S.  Geol.  Surv.,  Min.  Res.  1883-1884:  592,  1885.  (Ores 
and  deposits.)  3.  Brock,  Min.  Soc.  Nova  Scotia,  Jour.  XVII: 
50.  (N.  B.)  4.  Chapin,  U.  S.  Geol.  Surv.,  Bull.  592:  385  and  397, 
1914.  (Seward  Penin.)  5.  Collier,  U.  S.  Geol.  Surv.,  Bull.  225,  1904. 
(Alaska  and  general.)  6.  Collier,  U.  S.  Geol.  Surv.,  Bull.  340:  295. 
1908.  (Wash.)  7.  Fay,  Amer.  Inst.  Min.  Engrs.,  Bull.  Sept.,  1907, 
(Cape  Prince  of  Wales,  Alas.)  8.  Fawns,  Tin  Deposits  of  the  World, 
London,  1905.  9.  Ferguson  and  Bateman,  Econ.  Geol.  VII:  209, 
1912.  (Geologic  features.)  10.  Graton,  U.  S.  Geol.  Surv.,  Bull.  293, 
1906.  (S.  Appalachians.)  11.  Graton,  U.  S.  Geol.  Surv.,  Bull.  260: 
188,  1905.  (N.  Ca.  and  S.  Ca.)  12.  Hess,  Smithson,  Misc.  Collections, 


MINOR  METALS  819 

LVIII,  No.  2,  1912.  (Bibliography.)  13.  Hess  and  Graton,  U.  S. 
Geol.  Surv.,  Bull.  260:  161,  1905.  (Occurrence  and  distribution.) 
14.  Hess,  U.  S.  Geol.  Surv.,  Bull.  380:  134,  1909.  (S.  Dak.)  15. 
Knopf,  U.  S.  Geol.  Surv.,  Bull.  358,  1908.  (Alas.)  16.  Miller,  Can. 
Min.  Jour.,  XXXII:  582,  1911.  (Ont.)  17.  Piers,  Nova  Scotia 
Inst.  Sci.,  Proc.  and  Trans.,  XII,  Pt.  3:  239,  1912.  (N.  S.)  18.  Rich- 
ardson, U.  S.  Geol.  Surv.,  Bull.  285:  146,  1906.  (Franklin  Mts.,  Tex.) 

19.  Singewald,  Econ.  Geol.,  VII:    263,  1912.     (Genetic  relationships.) 

20.  Umpleby,  U.  S.  Geol.  Surv.,  Bull.  528,  1913.     (Lemhi  Co.,  Ido.) 

21.  Watson,  Min.  Res.  Va.,  1907:   567.     (Va.)     22.  Weed,  U.  S.  Geol. 
Surv.,   Bull.  213:    99,   1903.     23.  Ziegler,   Min.  and  Sci.  Pr.,  CVIII, 
Nos.  15  and  16,  1914.     (Harney  Peak,  S.  Dak.,  pegmatites.) 


TITANIUM 

Ore  Minerals.  —  While  more  than  sixty  mineral  species  con- 
tain titanium,  the  largest  concentrations  of  the  element  occur 
as  rutile  (TiCb,  60  per  cent  Ti  when  pure),  ilmenite,  or  titani- 
ferous  magnetite  (see  p.  520).  Rutile  is  at  present  the  chief 
source  of  the  element,  but  even  the  workable  deposits  of  this 
are  few,  widely  separated,  and  insufficient  to  supply  the  world's 
demand,  so  that  it  has  been  necessary  for  some  uses  to  turn  to 
ilmenite  or  highly  titaniferous  magnetites. 

Mode  of  Occurrence  (4) .  —  Rutile  is  formed  as  a  constituent 
of:  (1)  igneous  rocks:  (2)  pegmatite  dikes:  (3)  contact-meta- 
morphic  deposits;  (4)  veins;  and  (5)  regionally  metamorphosed 
rocks.  Of  these,  1  and  2,  rarely  3  and  5,  serve  as  important 
sources  of  rutile. 

While  rutile  may  occur  in  both  volcanic  and  plutonic  igneous 
rocks,  most  of  the  known  commercially  important  deposits 
are  associated  with  gabbro  (including  anorthosite),  and  usually 
formed  by  magmatic  differentiation.  The  region  of  Amherst 
and  Nelson  counties  in  Virginia,  Bay  St.  Paul,  Quebec,  Canada, 
and  Kragero  area  in  southern  Norway,  are  of  this  type.  A 
second  important  type  found  in  Virginia,  occurs  as  dike-like 
bodies  of  the  ultrabasic  igneous  rock  nelsonite  (4). 

Rutile  and  ilmenite  have  been  found  in  apatite  veins  in  Norway 
and  Sweden,  and  in  pegmatite  dikes  in  Virginia  (4)  and  Texas  (4). 

It  may  also  be  found  in  placer  deposits,  as  it  is  resistant  to 
weathering. 

Distribution  of  Rutile  in  the  United  States  (4).  —  Although 
found  in  the  eastern  United  States  from  New  England  to 
Alabama,  only  the  Virginia  deposits  are  of  commercial  value 


820 


ECONOMIC  GEOLOGY 


and  have  supplied  the  entire  domestic  production  since 
1902. 

Here  there  are  two  areas,  viz.,  the  Amherst-Nelson  County 
(Fig.  290),  one  on  the  northwest  edge  of  the  Piedmont  Plateau, 

and  the  Goochland  and  Han- 
over counties  area,  near  the 
central-eastern  margin  of  the 
same  province. 

In  the  Nelson  county  area 
the  rocks  are  all  igneous,  de- 
rived from  a  common  parent 
magma,  and  characterized  by 
the  prominence  of  apatite,  il- 
menite,rutile,and  more  rarely 
titaniferous  magnetite.  The 
rock  types  present  are:  (1) 
Biotite  -  quartz  monzonite 
gneiss  and  schists,  which  form 
the  country  rock;  (2)  syen- 
ite, the  most  important  rock 
type  of  the  rutile  district, 
consisting  chiefly  of  andesine 
feldspar  and  a  little  blue 

quartz,  a  hornblendic  (secondary  from  pyroxene)  facies  containing 
abundant  blue  quartz  and  andesine  feldspar,  and  near  its  margin, 
rutile,  and  lesser  amounts  of  ilmenite  and  apatite;  (3)  gabbro; 
(4)  nelsonite,  a  rock  occurring  usually  along  the  border  portion 
of  the  syenite,  and  composed  chiefly  of  apatite,  with  ilmenite 
or  rutile,  or  both  in  varying  proportions;  (5)  gabbro-nelsonite 
intermediate  between  3  and  4;  6,  diabase  dikes. 

The  rutile  occurs  as  grains  and  segregations  in  the  syenite, 
or  as  a  constituent  of  the  dike-like  nelsonite  bodies.  In  the 
former  it  varies  in  quantity  from  sparsely  disseminated  grains, 
up  to  30  per  cent  of  the  mass,  but  in  the  quarries  near  Roseland 
(Plate  LXXV,  Fig.  2)  averages  4  or  5  per  cent. 

The  rock  is  milled  and  both  the  rutile  and  ilmenite  saved. 
Nelsonite  rutile  was  also  mined  (Fig.  291)  formerly. 

In  the  Goochland-Hanover  counties  area  the  rutile  occurs  in 
pegmatite. 

Canada  (3) .  —  The  chief  known  occurrence  of  Canadian  rutile 
is  near  St.  Urbain,  north  of  Bay  St.  Paul,  Quebec.  The  ilmenite- 


FIG.  290.  —  Map  showing  location  and 
relations  of  rutile  deposits  in  Nelson 
County,  Va.  (After  Watson,  Min. 
Res.  Va.,  1907.) 


MINOR  METALS 


821 


rutile  deposits  occur  in  anorthosite.     The  larger  ilmenite  bodies 

form  elongated  masses,  with  usually  sharp  boundaries,  and  most 

of  them  are  free  from  rutile. 

A  second,  and  more  important 

type  is  a  rutile  and  sapphirine- 

bearing  ilmenite.     Both  types 

are   magmatic   differentiation 

products.        A      considerable 

quantity  of    ore  was  shipped 

in  1910. 

Other  Foreign  Deposits  (4). — • 
At  Kragero,  Norway,1  rutile  occurs 
in  a  large  aplite  dike,  either  as  dis- 
seminated grains,  or  more  important 
as  schlieren,  representing  local  en- 
richments of  the  mineral.  In  South 
Australia,  (4)  rutile  is  known  to 
occur  near  Mount  Crawford,  about 
25  miles  northeast  of  Adelaide,  the 
enclosing  rock  being  presumably 
pegmatite. 

Uses.  —  Titanium  is  used 
for  producing  yellow  under- 
glaze  colors  on  pottery,  and 
also  in  the  manufacture  of 
artificial  teeth,  to  give  them  «> 50  WFC* 

an  ivory  tint.      Another  USe  is   FlG-   291.  —  Plans  and  vertical  section  in 
,i  n  /.  ,  •,  General   Electric   Company's  mine,  Nel- 

in   the    alloy    ferro-titamum.      son  County>  Va.    (After  Watson  and  Ta_ 
Its   commercial   values    as   a     ber,  Va.,  Geol.  Surv.,  Bull.  1 1 1- A.) 
steel-hardening  metal  are  not 

yet  thoroughly  proven,  but  from  .5  to  3  per  cent  titanium  appears 
to  materially  increase  the  transverse  and  tensile  strength  of  steel. 
By  the  use  of  the  electric  furnace,  ferro-titanium  can  be  pro- 
duced directly  from  the  ores,  which  would  open  a  use  for  our 
American  titaniferous  magnetites.  Rutile  is  used  in  electrodes 
for  arc  lamps. 

Production.  —  The  domestic  production  in  1914  came  from 
Roseland,  Nelson  County,  Va.,  and  amounted  to  94  tons  of  rutile, 
carrying  95  per  cent  TiC>2  and,  as  a  by-product,  89  tons  of 
ilmenite,  carrying  about  55  per  cent  of  TiC>2.  Concentrated 

1  Watson,  Amer.  Jour.  Sci.,  XXXIV:  509,  1912;  Vogt,  Amer.  Inst.  Min. 
Engrs.,  XXX:  646,  1901. 


SECTION  ON  LINE  A-B 


822 


ECONOMIC  GEOLOGY 


rutile  sells  for  $50  to  $400  per  ton,  depending  on  purity,  fineness 
of  crushing,  and  quantity  purchased. 


ANALYSES  OF  RUTILE 


I 

II 

III 

IV 

TiO2 

95  71 

98  80 

53  35 

97  68 

FeO  
SiO 

2.35 
92 

1.68 

23 

24.49 
2  24 

.81 
1  06 

Cr2O3  

.02 

.07 

39 

V2O3  

15 

20 

55 

99.15 

101.01 

100.49 

I.  Nelson  County,  Va.,  syenite  rutile;  II.  Nelson  County,  Va.,  nelsonite 
rutile;  III.  Rutile  and  sapphirine-bearing  ilmenite,  St.  Urbain,  Que., 
partial  analysis;  IV.  Kragerite  rutile  from  Kragero,  Norway. 

REFERENCES    ON   TITANIUM 

1.  Baskerville,   Eng.    and   Min.    Jour.,    LXXXVII:     10,    1909.     (General.) 

2.  Hess,  Min.  World,  XXIII:    305,  1910.     (Goochland-Hanover  Cos.) 

3.  Warren,  Amer.  Jour.  Sci.,  XXIII:  263,  1912.     (Quebec.)     4.  Watson 
and  Taber,  Va.  Geol.  Surv.,  Bull.  3-A,  1913.     (Va.  and  general.)     5. 
Watson,  U.  S.  Geol.  Surv.,  Bull.  580,  1914.     (e.  U.  S.) 


TUNGSTEN 

Ore  Minerals.  —  Four  minerals  may  serve  as  important 
sources  of  tungsten,  viz.:  hubnerite  (MnW04,  76.6  per  cent 
WO3);  wolframite  ((FeMn)W04,  76.4  per  cent  WOa);  scheelite 
(CaW04,  80.6  per  cent  WO3);  ferberite  (FeWO4,  76.3  per  cent 
WO3). 

Of  these  the  wolframite  is  the  most  abundant,  while  scheelite 
and  ferberite  are  somewhat  rare.  The  commercially  important 
occurrences  include:  (1)  quartz  veins;  (2)  pegmatite  dikes 
(or  veins);  (3)  placers;  (4)  contact  metamorphic  zones;  and 
(5)  replacement  deposits. 

The  inclosing  rocks  may  be  volcanic  or  plutonic  igneous  ones, 
metamorphic  gneisses  and  schists,  or  even  sedimentaries. 
The  tungsten  mineral  forms  the  most  prominent  mineral  in  a 
deposit,  or  occurs  as  a  subordinate  one  in  veins  carrying  tin, 
gold,  or  silver. 


MINOR   METALS  823 

Among  the  minerals  that  may  be  found  accompanying  tungsten 
are  galena,  pyrite,  siderite,  quartz,  chalcopyrite,  pyrrhotite, 
fluorite,  tetrahedrite,  sphalerite,  barite,  cassiterite,  topaz,  arsen- 
opyrite,  etc. 

The  tungsten  minerals  may  occur  in  the  deposits  as  dissemina- 
tions, pockets  or  masses,  or  in  some  veins  in  bands. 

Distribution  in  the  United  States.  —  Tungsten  minerals  are 
known  to  occur  at  a  number  of  localities  in  the  United  States, 
and  yet  but  very  few  of  these  are  normally  of  commercial  impor- 
tance, the  quantity  available  usually  exceeding  the  demand. 
The  abnormal  conditions  produced  by  the  European  war,  and 
consequent  enormously  high  prices,  have  stimulated  the  develop- 
ment of  tungsten  deposits  in  the  United  States. 

A  few  of  the  occurrences  are  referred  to  below,  partly  to  give 
some  idea  of  the  mode  of  occurrence. 

Colorado  (10).  —  The  most  important  tungtsen  deposits  of 
Colorado  are  found  in  southeastern  Boulder  County.  The 
country  rock,  which  is  pre-Cambrian  granite  and  gneiss,  has 
been  subjected  to  fissuring  accompanied  by  crushing  and  brec- 
ciation,  and  in  the  open  spaces  thus  formed  the  ore  mineral 
ferberite  has  been  deposited.  The  metalliferous  solutions  also 
carried  much  silica,  and  the  following  important  periods  of 
mineralization  have  been  distinguished,  each  separated  by 
secondary  movement  and  brecciation  along  the  veins:  1,  silici- 
fication  and  partial  cementation  of  breccia  with  slight  depo- 
sition of  tungsten;  2,  deposition  of  tungsten;  3,  precipitation 
of  silica  followed  by  second  important  deposition  of  tungsten. 
There  is  also  a  strong  suggestion  of  solution  and  secondary 
enrichment.  The  friable  character  of  the  ferberite  and  the 
highly  siliceous  nature  of  some  of  the  ores  cause  some  difficulty 
in  concentration. 

These  deposits  form  an  important  domestic  source  of  tung- 
sten at  the  present  time. 

Arizona  (3,  16,  22). —  Hiibnerite  is  found  irregularly  distrib- 
uted in  vertical  quartz  veins  cutting  granites  and  gneissic  rocks, 
near  Dragoon,  Cochise  County. 

California  (l).  —  In  the  Atolia  district  of  San  Bernardino 
County  (24),  the  second  important  domestic  source,  the  ore 
mineral  scheelite  occurs  in  veins  with  quartz  and  calcite  in 
grano-diorite  and  schist.  The  veins  occupy  a  shear  zone. 

Nevada   (26).  —  Veins  of  hubnerite  are  found  in  a  granite  por- 


824  ECONOMIC  GEOLOGY 

phyry  in  the  Tungsten  mining  district  southeast  of  Ely.  The 
gangue  is  quartz  with  a  little  fluorite,  pyrite,  and  scheelite. 

South  Dakota  (14).  —  Wolframite  is  found  near  Lead  City  as 
flat,  horizontal,  but  irregular  masses,  associated  with  the  oxidized, 
refractory  siliceous  gold  ores.  These  ores  are  replacements  of  a 
dolomite  deposited  by  uprising  thermal  solutions. 

Canada  (7,  15,  25).  —  Tungsten  ores  have  been  reported 
from  a  number  of  localities  in  Canada,  but  the  production  is 
small  and  irregular,  and  comes  from  the  scheelite-quartz  veins 
of  Nova  Scotia.  Other  occurrences  have  been  recorded  from 
Beauce  County,  Quebec,  and  the  Slocan  district  of  British  Col- 
umbia (15,  25). 

Other  Foreign  Deposits.  —  Burma  and  the  Shan  States  form  the  most 
important  source  of  the  world's  supply,  the  wolframite  being  obtained 
from  placers,  derived  from  lodes,  where  it  is  associated  with  cassiterite  and 
quartz. 

Queensland  l  and  New  South  Wales  2  have  wolframite  in  quartz  veins, 
greisen  and  placers. 

In  Portugal,  the  third  largest  producer,  wolframite,  associated  with 
scheelite  and  tungstite  (WO3),  as  well  as  cassiterite,  pyrite,  arsenopyrite, 
tourmaline  and  fluorite,  is  found  in  veins  and  stockworks. 

Uses  of  Tungsten.  —  Most  of  the  tungsten  produced  is  used  in 
the  manufacture  of  tool  steel,  and  the  industry  therefore  depends 
to  a  large  extent  on  the  condition  of  the  steel  industry.  Tung- 
sten forms  a  number  of  alloys  with  other  metals  such  as  iron, 
aluminum,  nickel,  copper,  titanium,  tin,  etc.  It  is  also  employed 
to  a  considerable  extent  for  incandescent  lamp  filaments.  Ferro- 
tungsten  is  used  in  the  manufacture  of  tungsten  steel,  and  the 
fluorescent  properties  of  tungstate  of  lime  make  it  useful  in  the 
Rontgen  ray  apparatus.  Tungsten  is  also  employed  for  color- 
ing glass,  sodium  tungstate  is  used  in  fireproofing  curtains  and 
draperies,  while  other  tungsten  salts  are  used  for  weighting 
silks. 

Production.  —  The  United  States  production  in  1914  amounted 
to  990  short  tons  of  concentrates  carrying  60  per  cent  WOs, 
valued  at  $435,000,  which  was  547  tons  less  than  1913.  For 
the  first  time  the  Atolia,  Calif.,  district  exceeded  the  Boulder 
County,  Colo.,  one. 

The   world's   production   for   1912,   the   last   year   for   which 

1  Cameron,  Queensland  Geol.  Surv.,  Kept.  188,  1904. 

2  Carne,  N.  S.  W.  Geol.  Surv.,  Min.  Res.  No.  15,  1912. 


MINOR  METALS  825 

practically    complete    statistics    are    available,  was   9654    short 
tons  of  concentrates  carrying  60  per  cent  WOs. 

REFERENCES  ON  TUNGSTEN 

1.  Aubury,  Calif.  State  Ming.  Bur.,  Bull.  38:  372.  (Calif.)  2.  Auerbach, 
Eng.  and  Min.  Jour.,  LXXXVI,  1908.  (Cceur  d'Alene,  Ido.)  3. 
Blake,  Min.  Indus.,  VII:  720,  1899.  (Ariz.)  4.  Baskerville,  Eng. 
and  Min.  Jour.,  LXXXVII:  203,  1909.  5.  Cooper,  Eng.  and  Min. 
Jour.,  LXVII:  499.  (San  Juan  Co.,  Col.)  6.  De  Wolf,  Eng.  and 
Min.  Jour.,  Apr.  15,  1916.  (Ariz.)  7.  Faribault,  Can.  Geol.  Surv., 
Sum.  Rep.,  1909:  228.  (N.  S.)  8.  Fitch  and  Loughlin,  Econ.  Geol., 
Jan.,  1916.  (Leadville,  Colo.)  9.  Fleck,  Min.  and  Sci.  Pr.,  CXII: 
134,  1916.  (Prep'n  of  tungsten  metals.)  10.  George,  Col.  Geol.  Surv., 
1st  Rept.,  1908.  (Col.,  general,  and  bibliography.)  11.  Hess  and  Schaller, 
U.  S.  Geol.  Surv.,  Bull.  583,  1914.  (Colorado  ferberite  and  wolframite 
series.)  12.  Hills,  Min.  Soc.  N.  S.,  Jour.,  XVII:  55,  1912-13;  also 
Can.  Min.  Inst.,  XV:  477,  1913.  (Nova  Scotia.)  13.  Hobbs,  U.  S. 
Geol.  Surv.,  22d  Ann.  Rept.,  II:  13,  1902.  (Conn.)  14.  Irving, 
U.  S.  Geol.  Surv.,  Prof.  Pap.  XXVI:  158.  (S.  Dak.)  15.  Johnston 
and  Willmott,  Can.  Geol.  Surv.,  1904.  (Canada.)  16.  Joseph,  Eng. 
and  Min.  Jour.,  LXXXI:  409.  (Wash.)  17.  Kellogg,  Econ.  Geol., 
I:  654,  1906.  (Ariz.)  18.  Lindgren,  Econ.  Geol.,  II:  111,  1907. 
(Col.)  19.  McDonald,  Min.  and  Sci.  Pr.,  CXII:  40,  1916.  (Scheelite 
mining  and  grading.)  20.  Ransome,  U.  S.  Geol.  Surv.,  Bull.  182:  86, 
256.  (Silverton,  Col.)  21.  Ransome,  U.  S.  Geol.  Surv.,  Prof.  Pap. 
62:  103,  1908.  (Cceur  d'Alene,  Ido.)  22.  Rickard,  Eng.  and  Min. 
Jour.,  LXXVIII:  263,  1904.  (Ariz.)  23.  Rowe,  Min.  Wld.,  XXIX: 
778.  (Idaho.)  24.  Runner,  Min.  and  Sci.  Pr.,  CXII:  405,  1916. 
(Geology  of  tungsten.)  25.  Walker,  Can.  Min.  Inst.,  XI:  367,  1908. 
(Can.)  26.  Weeks,  U.  S.  Geol.  Surv.,  21st  Ann.  Rept.,  VI:  319,  also 
ibid.,  Bull.  340:  263.  (Nev.)  27.  Winchell,  Econ.  Geol.,  V:  158, 
1910.  (Certain  tungsten  minerals.)  28.  Hess,  U.  S.  Geol.  Surv., 
Min.  Res.  (General,  and  U.  S.  occurrences.) 

URANIUM  AND  VANADIUM 

Ore  Minerals.  —  The  minerals  which  carry  one  or  the  other, 
or  both  of  these  elements,  and  which  are  of  commercial  im- 
portance are:  carnotite  (K20-2UO3-  V205+8H2O);  roscoelite 
or  vanadium  mica  (H8K(MgFe)(AlV)4 (8^)3)12);  pitchblende  or 
uraninite  (UsOs);  uvanite  (2U03  •  3V2O5  •  15H20) ;  descloisite 
(ZnPb(OH)V04);  pofrorafeO^Ss);  andvanadinite  (Pb5Cl(PO4)3). 
Of  these  carnotite  is  the  most  important  ore  in  the  United 
States,  not  only  because  of  its  uranium  content,  which  is  in 
more  demand  than  the  vanadium,  but  also  because  it  carries 
radium,  so  much  sought  after  now  because  of  its  radio-active 


826  ECONOMIC  GEOLOGY 

properties.  Associated  with  the  carnotite  is  more  or  less 
roscoelite. 

Distribution  of  Uranium  and  Vanadium  in  the  United  States 
(2,  12).  —  The  chief  source  of  uranium  and  vanadium  in  the 
United  States  is  a  somewhat  extensive  area  in  western  Colorado 
and  adjoining  portions  of  Utah  (6,  8).  The  ore  minerals  occur 
in  the  lower  member  of  the  La  Plata  (Jurassic)  sandstone,  being 
found  either  in  the  disseminated  form,  or  in  joint  fractures  of 
the  rock. 

The  deposits  follow  a  seam  which  indicates  an  apparent 
unconformity,  and  vary  in  thickness  from  1  or  2  inches  to  over 
30  feet.  Much  of  the  ore  is  low  grade,  and  sorting  is  necessary 
to  give  a  shipping  product  averaging  2  per  cent  UsOg.  Locally 
it  may  run  much  higher.  The  vanadium  content  in  a  large  pro- 
portion of  the  ore  is  1  per  cent  V2Os,  but  some  of  it  runs  consider- 
ably higher. 

The  origin  of  these  deposits  has  been  a  puzzling  problem. 
Vanadium  is  known  to  occur  in  small  quantities  in  many  sedi- 
mentary rocks,  and  the  present  deposits  may  represent  concen- 
trations by  surface  waters,  although  Hess  suggests  that  the  dikes 
found  in  this  region  may  have  some  connection  with  the  min- 
eralization of  the  sandstone. 

Deposits  of  carnotite  in  sandstone  are  also  being  worked  near 
Green  River,  Utah  (s),  and  the  year  1914  saw  the  first  com- 
mercial production  of  this  mineral  from  the  Henry  Mountains, 
Utah,  while  near  Temple,  Utah,  there  was  begun  the  production 
of  uvanite,1  a  radium-bearing  mineral  new  to  science. 

At  Cutter,  Sierra  County,  N.  Mex.  (7),  vanadinite  associated 
with  lead,  zinc  and  copper,  has  been  found  in  veins  cutting 
Carboniferous  limestone. 

Pitchblende  has  been  found  at  a  number  of  localities  in  the 
United  States,  but  the  most  important  deposits  are  those  found 
near  Central  City,  Gilpin  County,  Colo.  The  mines  were 
originally  worked  for  gold  (12,  14). 

Foreign  Deposits. — The  important  European  deposits  of  pitchblende 
are  found  at  Joachimsthal,2  Austria,  and  at  Johanngeorgenstadt,  Marien- 
berg,  Freiberg  and  Schneeberg,  in  Saxony.  The  veins  are  referred  to  under 
nickel  and  cobalt. 

Of  great  importance  are  the  vanadium  deposits  at  Mmassagra,  20  miles 

1  Hess  and  Schaller,  Wash.  Acad.  Sci.,  Jour.,  IV:   576,  1914. 
2Becke,  Zeitschr.  prak.  Geol.,  1905:    148. 


MINOR  METALS  827 

from  Cerro  de  Pasco,  Peru.1  The  ore  mineral,  patronite  (V2SJ,  is  found  as 
a  lens-shape  mass  in  red  shales,  associated  with  a  black  hydrocarbon  called 
quisquerite. 

Production.  —  The  United  States  in  1914  produced  4294 
short  tons  of  dry  ore,  carrying  87.2  tons  of  uranium  oxide,  and 
22.3  grams  of  metallic  radium.  The  ore  was  valued  at  $441,300, 
and  the  production  is  the  largest  yet  made. 

Little  is  paid  for  the  vanadium,  it  being  the  uranium  and  radium 
that  are  chiefly  desired.  Unfortunately  most  of  the  ore  has  been 
shipped  abroad  in  the  past,  but  several  companies  have  been 
started  in  the  United  States  for  producing  radium  salts. 

Uses  of  Uranium.  —  Uranium  minerals  are  radio-active,  and 
the  oxide  is  used  to  some  extent  as  a  coloring  agent  in  rjottery 
glazes  and  iridescent  glass.  Certain  salts  have  a  limited  use  in 
chemistry  and  medicine. 

Uranium  can  be  alloyed  with  steel,  but  alloys  of  other  metals 
having  similar  properties  are  cheaper  to  produce. 

Uses  of  Vanadium.  —  The  main  use  of  vanadium  is  as  an 
alloy  in  steels  where  great  toughness  and  torsional  strength  are 
needed.  It  is  sometimes  used  in  certain  tungsten  alloys  for 
making  high-speed  tool  steel.  Metavanadic  acid  has  been  used 
as  a  substitute  for  bronze  paint,  and  vanadium  chloride  is  used 
as  a  mordant  in  printing  fabrics,  and  the  trioxide  as  a  mordant 
in  dyeing. 

REFERENCES  ON  URANIUM  AND  VANADIUM 

1.  Baskerville,  Eng.  and  Min.  Jour.,  LXXXVII:  257,  518,  1909.  (Gen- 
eral.) 2.  Clarke,  U.  S.  Geol.  Surv.,  Bull.  616:  705,  1916.  (General.) 
3.  Fleck,  Col.  Sch.  of  M.  Quart.,  Ill,  No.  3,  1908.  (Col.)  4.  Gale, 
U.  S.  Geol.  Surv.,  Bull.  340:  257,  1908.  (Routt  Co.,  Col.)  5.  Gale, 
U.  S.  Geol.  Surv.,  Bull.  315:  110,  1907.  (Col.)  6.  Hess,  U.  S.  Geol. 
Surv.,  Bull.  530:  142,  1913.  (Placerville,  Colo.)  7.  Hess,  Ibid.:  157, 
1913.  (N.  Mex.)  8.  Hess,  Ibid.i'lQl,  1913.  (Grand  River,  Utah.)  9.  Hil- 
lebrand  and  Ransome,  Amer.  Jour.  Sci.,  4th  ser.,  X:  120,  1900.  (Col.) 
10.  Hillebrand,  Amer.  Jour.  Sci.,  XXIV:  141,  1907.  (Patronite.)  11. 
Moore  and  Kithil,  Bur.  Mines,  Bull.  70,  1914.  (U.  S.  and  general.) 
12.  Parsons  and  others,  Bur.  Mines,  Bull.  104,  1915.  (Extraction 
radium,  uranium  and  vanadium  from  carnotite.  13.  Pearce,  Col.  Sci. 
Soc.,  Proc.  V:  156,  1895.  (Uraninite,  Colo.)  14.  Rickard,  F.,  Min. 
and  Sci.  Pr.,  CM:  851,  1913.  (Pitchblende,  Gilpin  Co.,  Colo.)  15. 
Wherry,  Amer.  Jour.  Sci.,  XXXIII:  574,  1912;  and  U.  S.  Geol.  Surv., 
Bull.  580:  147,  1914.  (Carnotite,  Pa.)  16.  Smith,  Amer.  Inst.  Min. 
Eng.,  Trans.  XXXVIII:  698,  1907.  (Present  sources  and  uses.) 

i  Hewett,  Amer.  Inst.  Min.  Engrs.,  Trans.  XL:   274,  1910. 


INDEX 


Abrasives,  artificial,  296. 

•   buhrstones,  284. 

corundum,  292. 

diamonds,  295. 

diatomaceous  earth,  290. 

distribution,  286. 

emery,  292. 

feldspar,  290. 

garnet,  290. 

grindstones,  286. 

millstones,  284. 

novaculite,  287. 

oilstones,  287. 

pebbles,  295. 

pulpstones,  287. 

pumice,  288. 

production,  296. 

quartz,  290. 

references  on,  296. 

tripoli,  290. 

volcanic  ash,  289. 

whetstones,  287. 
Actinolite,  298. 
Adams,  F.  D.,  283,  437. 
Adams,  G.  I.,  134,  135,  136.  208,  259,  400, 

655. 

Adiassevich,  A.,  113. 
Adobe,  176. 
Africa,  asbestos,  307;     diamond,    295,   381; 

gold,  737;     mica,  368;     phosphate,  280. 
Aguilera,  J.  G.,  730. 
Akron,  N.  Y.,  190. 

Alabama,  bauxite,    751;     clay,    179,     180; 
coal,   35;    granite,    146;      graphite,    349; 
hematite,  542,  limonite,  556;    pyrite,  403. 
Alabaster,  244. 
Alabaster,  Mich.,  250,  253. 
Alameda  County,  Calif.,  46. 
Alaska,   Auriferous    lodes,    693;     chromite, 
791;     coal,    46;     copper,    588,    602,    605, 
613;    gold,    692,  734;    gypsum,   253;    pe- 
troleum,   109;   platinum,  806;    tin,    811, 
815. 

Albany,  N.  Y.,  335. 
Alberta,   cement,    202;     coal,    50;     natural 

gas,    115;     phosphate,    278;     salt,  225. 
Albert  County,  N.  B.,  125. 
Albertite,  118. 
Albert  Mines.  N.  B.,  118. 
Albite,  322. 
Alexander,  Ark.,  338. 
Algeria,  antimony,  781;   onyx,  154. 
Algiers,  280. 
Allen,  E.  T.,  327,  564,  G18,  655. 


Allochthonous  coal,  10,  12. 
Almaden,  Spain,  775. 
Almandite,  290,  383. 
Almeria,  Spain,  291. 
Altenberg,  Saxony,  469,  816. 
Aluminum,  ore  minerals,  750. 
production,  756. 
uses,  755. 
See  Bauxite. 
Alundum,  296,  756. 
Alunite,  for  potash,  242. 

Goldfield,  Nev.,  712. 
Alunitization,  487. 
Amatrice,  388. 
Amber  ore  sand,  96. 
Amelia,  Va.,  810. 
Analyses  of,  anthracite,  9. 

asbestos  minerals,  298. 

bauxite,  751,  754. 

barite,  315. 

bitumens,  122. 

bituminous  coal,  9. 

brines,  222. 

brines,  solid  matter  in,  226. 

cadmium  blende,  789. 

calcium  chloride  brines,  230. 

chromite,  790. 

clays,  175. 

Clinton  iron  ore,  543. 

coal  ash,  10. 

coal,  elementary,  18. 

coals,  U.  S.,  8. 

copper  ores,  weathered,  478. 

corundum,  292. 

diatomaceous  earth,  319. 

feldspar,  323. 

fluorspar,  333. 

foundry  sands,  335. 

fuller's  earth,  338. 

gases,  manufactured,  79. 

glass  sand,  341. 

graphite,  344,  348. 

greensand,  279. 

greisen  rock,  813. 

gypsum,  253,  256. 

hematite  paint  ore,  371. 

hydraulic  lime  rocks,  189. 

iron  ores,  Brazil,  548. 

iron  ores,  Canada,  547. 

iron  ores,  Lake  Superior,  527, 
528. 

lake  waters,  211. 

limestones,  187. 

limonites,  557. 

lithographic  stone,  354. 

magnesite,  359. 

829 


830 


INDEX 


Analyses  of,  magnetite,  516. 

magnetite,  titaniferous,  521. 

manganese,  Ga.,  764. 

Mediterranean  water,  213. 

meerschaum,  363. 

mineral  waters,  424. 

mine  waters,  443. 

monazite,  378. 

natural  cement  rocks,  190. 

natural  coke,  5. 

natural  gas,  78. 

natural  rock  cements,  191. 

ocherci,  372,  374. 

peat  bog,  layers  in,  1. 

petroleum,  71,  74. 

phosphate  rock,  272,  276. 

Portland      cement      materials, 
192. 

Portland  cements,  193. 

potash  brines,  239. 

pyrite,  403. 

residual  limonites,  554. 

rock  salt,  225. 

rutile,  822. 

sea  water,  211. 

semianthracite,  9. 

semibituminous  coal,  9. 

siderite  for  paint,  375. 

talc,  409. 

tripoli,  413. 

vein  bitumens,  120. 
Analysis  of,  blende.  Missouri,  644. 

borax  water,  Clear  Lake,  233. 

coal  gas,  79. 

coal,  proximate,  6. 

kaolin,  178. 

maltha,  122. 

oil  shale,  126. 

pozzuolan  cement,  188. 

producer  gas,  79. 

Searles  Lake  brine,  242. 

sphagnum,  1. 

sulphur,  Utah,  397. 

water  gas,  79. 
Anderson,  R.,  134,  321. 
Andesite,  for  building,  149,  162. 

for  cement,  202. 
Andrews,  E.  C.,  794. 
Anglesite,  622. 

Anhydrite,  difference  from  gypsum,  246. 
distribution,  244. 
mode  of  occurrence,  246. 
origin,  247. 

Annaberg,  Sax.,  787,  803 
Annabergite,  795. 
Anorthite,  322. 
Anrep,  A.,  69. 

Anthophyllite,  298,  300,  302. 
Anthracite,  analyses  of,  9. 
Canada,  50. 
Pennsylvania,  29. 
properties  of,  5. 

Russia,  52. 

Wales,  52. 

Anthraxolite,  80,  118. 
Anticlinal  theory  of  oil,  87. 
Antimony,  Canada,  780. 

deposits,  classification,  779. 
foreign  deposits,  781. 
from  blister  copper,  780. 


Antimony,  ore  minerals,  779. 
production,  782. 
references  on,  783. 
sources,  780. 
United  States,  779. 
uses,  781. 

Apatite,  as  fertilizer,  260. 
Apex,  Colo.,  573. 
Apgar,  F.  W.,  501. 
Appalachian  coal  field,  28. 
Apsdin,  J.,  191. 

Apsheron  Peninsula,  Russia,  113. 
Aquamarine,  383. 
Arber,  E.  A.  N.,  65. 
Arbuckle  Mts.,  Okla.,  147. 
Argall,  G.  O.,  634,  655. 
Argall,  P.,  633,  655,  674,  771. 
Argentite,  676. 

Arizona,  asbestos,  301;  building  stone,  149; 
copper,  573,  600,  611;  fluorspar,  330; 
garnet,  383;  gypsum,  252;  onyx,  154; 
peridot,  384;  potash,  242;  tungsten,  823; 
turquoise,  387. 

Arkansas,  antimony,  780;  asphalt,  120; 
bauxite,  754;  cement,  202;  coal,  41;  di- 
amond, 381;  granite,  147;  limonite,  556; 
manganese,  766;  novaculite,  287;  phos- 
phate, 277;  slate,  162;  syenite,  148;  zinc, 
646. 

Arkose,  158. 

Arnold,  R.,  66,  133,  134,  231,  321,  748. 
Arsenic,  foreign  deposits,  784. 
in  smelter  fumes,  783. 
ore  minerals,  783. 
production,  785. 
references,  786. 
United  States,  784. 
uses  of,  784. 
Arsenopyrite,  783. 
Artesian  water,  417. 
Asbestic,  307. 
Asbestine,  307. 
Asbestos,   analyses,  298. 
Canada,  302. 
cross  fiber,  298. 
foreign  deposits,  307. 
mass  fiber,  299. 
minerals,  298. 
occurrence,  298. 
origin,  305. 
production,  308. 
references,  308. 
slip  fiber,  299. 
types,  comparison  of,  299. 
United  States,  300. 
uses,  307. 

Ashburner,  C.,  135. 
Ashford,  Wash.,  9. 
Ashley,  G.  H.,  28,  37,  65,  66,  135,  184,  208, 

353,  758. 
Asia,  coal,  52. 
Aspen,  Colo.,  668. 
Asphalt,  lake,  121. 

production,  131. 
uses,  126. 
vein,  121. 
Asphaltite,  117. 
Atacamite,  568. 
Atlin,  B.  C.,  356. 
Attfield,  231. 


INDEX 


831 


Aubrey,  A.  J.,  756 

Aubury,  L..  167,  321,  400,  618,  825. 

Auerbaeh,  H.  S.,  825. 

Australia,  oil  shale,  125;   tantalum,  810. 

Austria,  barite,  316;  bismuth,  787;  coal 
52;  chromite,  792;  cobalt,  803;  graph- 
ite, 350;  iron,  548;  magnesite,  356; 
mercury,  775;  zinc,  651. 

Autochthonous  coal,  10. 

Avery  Island,  La.,  224. 

Azurite,  568. 


Babbitt  metal,  781. 
Babcock,  E.  J.,  67,  185. 
Bacteria,  iron,  549. 

sulphur,  394. 
Bagg,  R.  M.,  619. 
Bailey,  E.  H.  S..  259. 
Bailey,  G.  E.,  228,  237,  620. 
Bailey,  L.  W.,  136. 
Bain,  H.  F.,  65,  66,  184,  329,  334,  414,  497, 

619,  645,  656,  748. 
Baker,  M.  B.,  186. 
Baker  County,  Ore.,  698. 
Bakersfield,  Calif.,  338. 
Baku,  Russia,  113. 
Balakhariy  field,  113. 
Ball,  S.  H.,  209,  353,  370,  522,  537,  565,  566, 

619,  620,  656. 

Ballarat,  Victoria,  705,  706. 
Ball  clay,  176. 
Banat,  Hungary,  518. 
Bancroft,  G.  J.,  500. 
Bancroft,  H.,  486,  656,  657,  673,  745,  746, 

748,  778,  809. 
Bancroft,  J.  A.,  406,  620. 
Bancroft,  W.  D.,  256. 
Banff,  Alberta,  50,  278. 
Banka,  tin,  816. 
Barbados,  manjak,  121. 
Barber,  Kas.,  252. 
Barbour,  E.  H.,  67,  297. 
Barclay  coal  basin,  32. 
Bard,  D.  C.,  619. 
Barite,  analyses,  315. 

associated  minerals,  310. 

Canada,  316. 

deposits,  form  of,  309. 

foreign,  316. 

geologic  age,  310. 

mining,  316. 

occurrence,  309. 

origin,  316. 

production,  317. 

properties,  309. 

references  on,  318. 

United  States,  310. 

uses,  316. 

Barlow,  A.  E.,  296,  799,  805. 
Barnes,  C.,  747. 
Barnett,  V.  H.,  135. 
Barr,  J.  A.,  283. 
Barrell,  J.,  451,  497. 
Bartlesville,  Okla.,  102. 
Bartling,  R.,  318. 
Barton  Hill,  N.  Y.,  508. 
Barus,  C.,  498. 
Basalt,  for  building,  148. 


Baskenovo,  Russia,  307. 

Baskerville,  C.,  136,  390,  794,  810,  822  825 

827. 

Bassler,  R.  S.,  209. 
Bastin,  E.  S.,  68,  208,  327,  346,  353,  392, 

499,  619,  704,  745,  746. 
Bateman,  G.  M.,  812,  818. 
Bateson,  C.  E.  W.,  746. 
Batesville,  Ark.,  277. 
Bathurst,  N.  B.,  516,  547. 
Baux,  France,  750,  751,  755. 
Bauxite,  750,  751. 

analyses,  751. 

foreign  deposits,  755. 

impurities  in,  751. 

origin,  753,  754. 

production,  756. 

references,  758. 

United  States,  751. 

uses,  755. 

Bavaria,  copper,  573;    graphite,  350. 
Bawdwin  mines,  Burma,  673. 
Bayard  sand,  97. 
Bay  City,  Mich.,  38,  226. 
Bayley,  W.  S.,  421,  511,  564,  565. 
Bay  St.  Paul,  Que.,  819,  820. 
Bear  Creek,  Mont.,  8. 
Beauce  County,  Que.,  824. 
Beaume  scale,  72. 
Beaumont,  E.  de,  440,  813. 
Beaumont,  Tex.,  85,  106,  107. 
Beaver  Hill,  Ore.,  8. 
Beaver  sand.  96. 

Beck,  R.,  470,  497,  500,  518,  659,  729,  826. 
Becker,  G.  F.,  80,  133,  217,  456,  501,  747, 

772,  778. 

Bedded  deposits,  ores,  472. 
Bedford,  Ont.,  323. 
Bedford  stone,  150. 
Bedford  Village,  N.  Y.,  323. 
Bedford,  Virginia,  301. 
Beeler,  H.  C.,  748. 
Beeson,  J.  J.,  620. 
Belgium,  barite,    316;     coal,    52;     marble, 

153;   phosphate,  280. 
Bell,  J.  M.,  136,  567,  805. 
Bell  metal,  614. 
Bendigo,  Victoria,  705,  706. 
Bengal,  mica,  368. 
Berea  grit,  abrasive,  286. 
Berea  sand,  oil,  96. 
Berea  sandstone,  building,  158. 
Berg,  G.,  497. 

Bergeat,  A.,  497,  603,  609,  781. 
Berggiesshiibel,  Ger.,  811 
Berkeley,  W.  Va.,  341. 
Berlin,  Wis.,  336. 
Bernice  coal  basin,  Pa.,  32. 
Berthelot,  M.,  79. 
Beryl,  383. 
Bevier,  G.  M.,  620. 
Beyer,  S.  W.,  168,  185,  208. 
Beyschlag,  F.,  447,  497,  524,  548,  659,  672, 

673,  705,  708,  729,  730,  775,  803,  811. 
Bex,  Switz,  247. 

Big  Cottonwood  Canon,  Utah,  668. 
Big  Injun  sand,  96. 
Big  Stone  Gap  coalfield,  34. 
Bilbao,  Spain,  548,  559. 
Billiton  Islands,  816. 


832 


INDEX 


Bingham,  Utah,  580. 
Binns,  C.  F.,  184,  501,  646,  656. 
Birkenbine,  J.,  527,  564. 
Birmingham,  Ala.,  35,  542. 
'Bisbee,  Ariz.,  573. 
Bischof,  G.,  215,  395. 
Bischof,  K.,  184. 
Bishop,  I.  P.,  208. 
Bismite,  786. 

Bismuth,  foreign  deposits,  787. 
in  smelter  fumes,  786. 
ore  minerals,  786. 
production,  787. 
references  on,  788. 
United  States,  785." 
uses,  787. 
Bismuthinite,  786. 
Bismutite,  786. 
Bitumens,  albertite,  118. 

anthraxolite,  118. 
asphaltite,  117. 
gilsonite,  121. 
grahamite,  118. 
lake  asphalt,  121. 
maltha,  122. 
manjak,  121. 
ozokerite,  118. 
solid,  117. 
solid,  origin,  126. 
tabbyite,  121. 
uintaite,  121. 
vein,  117. 
wurtzilite,  121. 
Bituminous  coal,  analyses,  8,  9. 

properties  of,  2. 

Bituminous  rock,  analyses,  124. 
origin,  126. 
production,  131. 
properties,  124. 
references  on,  136. 
Black  band  ore,  559. 
Black  Fork  Mountain,  Oklahoma,  120. 
Black  Hills,  S.  Dak.,  148,  180,  811,  815. 
Black  Lake,  Que.,  306. 
Black  lignite,  2. 
Black  sand,  731. 
Blacksburg.Va.,9. 
Blackwelder,  E.,  283. 
Blagodat,  Russia,  807. 
Blake,  W.  P.,  66,  136,  259,  730,  745,  758, 

818,  825. 

Blandy,  J.  F.,  745. 
Blatchley,  R.  S.,  134. 
Blatchley,  W.  S.,  134,  185,  208,  390. 
Bleiberg,  Austria,  651. 
Bleininger,  A.  V.,  207,  208,  209. 
Blende,  621. 
Block  coal,  32. 
Blockton,  Ala.,  9. 
Blossburg  coal  basin,  32. 
Blount  Mountain  coal,  35. 
Blow,  A.  A.,  485,  634. 
Blue  billy,  559. 
Blue  ground,  382. 
Blue  Rapids,  Kas.,  252. 
Bluestone,  158. 
Bodenmais,  Bav.,  573. 
Bog  lime,  for  cement,  191. 
Bohemia,  silver-lead  ore,  672. 
Boise,  C.  W.,  390. 


Bolivia,  bismuth,    787;     copper,    603,    609: 

tin,  813,  816. 
Bone  coal,  31. 
Bonine,  C.  A.,  283. 
Bonne  Terre,  Mo.,  473. 
Book  Cliffs,  Utah,  5. 
Boracite,  233. 

Borates,  hot  spring  waters,  233. 
origin  of,  235. 
production,  236. 
references  on,  237. 
United  States,  233. 
uses,  236. 

Borax  Lake,  Calif.,  211. 

Borax.     See  Borates. 

Bordeaux,  A.  F.  J.,  730. 

Borneo,  diamond,  295;    petroleum,  113. 

Bornite,  568. 

Borooarbone,  296. 

Borts,  295,  380. 

Bosworth,  T.  O.,  133. 

Botetourt  Co.,  Va.,  754. 

Boulder,  Colo.,  108. 

Boulder  County,  Colo.,  823. 

Boulder,  Mont.,  442. 

Boulder  batholith,  Mont.,  593. 

Boundary  district,  Brit.  Col.,  590. 

Bourry,  E.,  184. 

Boutwell,  J.  A.,  259,  585,  620,  674. 

Bovard,  Nev.,  242. 

Bowen,  N.  L.,  229. 

Bow  Island,  Alberta,  115. 

Bowling  Green,  Ky.,  150. 

Bownocker,  J.  A.,  32,  67,  98,  134,  228,  230. 

Boyle,  Jr.,  A.  C.,  618. 

Bradford  sand,  97. 

Bradley,  R.  R.,  406. 

Brad,  Transylvania,  729. 

Braden  Mines,  Chile,  603. 

Brandenburg,  Ky.,  354. 

Branner,  J.  C.,  136,  184,  208,  278,  283,  340, 
639,  655,  758,  789. 

Bransky,  O.  E.,  340. 

Branson,  E.  B.,  216,  228. 

Brass,  614,  651. 

Braunite,  758. 

Brazil,  copper,  605;  diamond,  295;  gold, 
695;  iron,  548;  manganese,  768;  oil 
shale,  125;  monazite,  378;  topaz,  388. 

Breece  Hill,  Leadville,  786. 

Breger,  C.  L.,  228. 

Brewer,  W.  M.,  745. 

Brewster  County,  Tex.,  774. 

Bridges,  J.  H.,  400. 

Britannia  metal,  781. 

British  Columbia,  building  stone,  162;  ce- 
ment, 202;  clay,  181;  coal,  50;  copper, 
590;  diamonds,  382;  gold-silver,  686; 
gypsum,  255;  lead-silver,  659,  671;  mag- 
nesite,  356;  marble,  164;  platinum,  807; 
salt,  225;  sandstone,  164;  tungsten,  824. 

Broadhead,  G.  C.,  343. 

Broadtop  coal  basin,  32. 

Brochantite,  568. 

Brock,  R.  W.,  818. 

Brocken  Mountain,  Germany,  672. 

Brokaw,  A.  D.,  745. 

Broken  Hill,  N.  S.  W.,  659. 

Bromine,  references  on,  230. 
sources,  229. 


INDEX 


833 


Bromine,  uses,  229. 

Bromyrite,  676. 

Bronze,  614. 

Brooks,  A.  H.,  66,  133,  745,  793. 

Brookville  coal,  32. 

Broughton,  Que.,  298. 

Brown,  C.  S.,  66. 

Brown,  R.  G.,  746. 

Browne,  D.  H.,  805. 

Browne,  R.  E.,  732,  746. 

Brown  ore.     See  Limonite. 

Brownstone,  158. 

Brummell,  H.  P.  H.,  353. 

Brun,  P.,  441,  498. 

Bryan  Heights,  Tex.,  396. 

Buckingham,  Que.,  325,  349. 

Buckley,  E.  R.,  167,  168,  186,  209,  316,  318, 

646,  656. 

Buckman,  H.  O.,  184. 
Buehler,  H.  A.,  168,  208,  478. 
Buena  Vista,  Va.,  557. 
Buffalo,  N.  Y.,  190. 
Buhrstones,  defined,  284. 
sources,  284. 
Building  stone,  anorthosite,  148. 

Canada,  163. 

basalt,  148. 

chemical  composition,  143. 

diabase,  148. 

foreign,  146,  153,  164. 

gabbro,  148. 

granite,  144. 

life  of,  143. 

limestone,  149. 

marbles,  152. 

production,  165. 

properties,  138. 

quarry  water,  142. 

references  on,  167. 

rhyolite,  148. 

sandstone,  157. 

serpentine,  154. 

slate,  160. 

structure  affecting  quarry- 
ing, 144. 

United    States,     146,     152, 
158,  160. 

uses,  148,  154,  159. 
Bullfrog,  Nov.,  729. 
Burchard,  E.  F.,  67,  168,  204,  207,  318,  334, 

343,  377,  556,  566, 
Burgess,  J.  A.,  714,  747. 
Burke,  Ido.,  660. 

Burma,  lead-silver  ore,  673;   tungsten,  824. 
Burns,  Kas.,  253. 
Burrell,  G.  A.,  78. 

Burro  Mountains,  New  Mex.,  483,  601. 
Burrows,  A.  G.,  748. 
Burton,  Ga.,  409. 

Butler,  B.  S.,  243,  498,  617,  619,  620,  674. 
Butler,  G.  M.,  655. 
Butler  sand,  96. 
Butler,  Tenn.,  413. 
Butte,  Mont.,  443,  470,  593,  767. 
Buttram,  F.,  134,  297,  343. 
Butts,  C.,  66,  566. 
Byler,  E.  A.,  747. 

C 

Cable  Mine,  Mont.,  686. 
Cactus  Mine,  Utah,  592,  692. 


Caddo  field,  La.,  108. 

Cadmium,  occurrence,  788. 

references  on,  789. 
uses,  788. 

Cady,  G.  H.,  748. 

Cady,  H.  P.,  73. 

Caen  stone,  164. 

Cahaba  coal  field,  35. 

Cairnes,  D.  D.,  68,  620,  748,  749,  779,  783. 

Calabogie,  Ont.,  349. 

Calamine,  621. 

Calaverite,  675,  810.          * 

Calcareous  tufa,  150. 

Calcasieu  Parish,  La.,  396. 

Calcium  chloride,  230. 

Calgary,  Alberta,  111,  202. 

California,  basalt,  148;  bituminous  rock, 
124;  borax,  233;  cement,  202;  chromite, 
791;  clay,  180;  coal,  46;  copper,  573,  593, 
613;  diatomaceous  earth,  320;  feldspar, 
323;  gold,  692,  695;  granite,  148;  gyp- 
sum, 252;  magnesite,  356;  maltha,  122; 
manganese,  612,  766;  marble,  153;  mer- 
cury, 772;  onyx,  154;  petroleum,  102; 
placers,  731;  platinum,  806;  potash,  241; 
salt,  224;  slate,  162;  sodium  sulphate, 
231;  talc,  410;  tourmaline,  386;  tung- 
sten, 823. 

Calkins,  F.  C.,  619,  674. 

Callen,  A.  C.,  377. 

Calomel,  771. 

Calumet  conglomerate,  608. 

Calvin,  S.,  343,  566,  656. 

Cameron,  F.,  243. 

Cameron,  W.  E.,  794,  824. 

Campbell,  M.  R.,  2,  15,  19,  21,  65,  66,  133, 
233,  237,  343. 

Campbell's  Run  sand,  97. 

Campbell,  W.,  805. 

Camsell,  C.,  390,  452,  688,  749,  793,  808. 

Canada.     See  individual  provinces. 

Cananea,  Mex.,  592. 

Canaval,  R.,  362. 

Caney  Creek  sand,  97. 

Canmore,  Alberta,  50. 

Cannel,  Tex.,  43. 

Cannel  coal,  properties  of,  4. 

Cannelsburg,  Ky.,  36. 

Canon  City,  Colo.,  42,  367. 

Canyon  City,  Colo.,  810. 

Canton,  N.  Y.,  403. 

Cape  Lisburne,  Alas.,  48. 

Cape  Nome,  Alas.,  735. 

Cape  Yakataga,  Alas.,  110. 

Carbonado,  295,  380. 

Carbonate  ore,  iron,  559. 

Carbon  black,  116. 

Carbon  County,  Mont.,  44. 

Carbonite,  5,  35. 

Carbon  Mountain,  Alas.,  9. 

Carborundum,  296. 

Carll,  J.  F.,  134. 

Carlsbad,  Bohemia,  444. 

Carlstadt,  Alberta,  115. 

Carmel,  N.  Y.,  784. 

Carnallite,  214. 

Came,  J.  E.,  136,  824. 

Carney,  F.,  343. 

Carnotite,  825. 

Carpenter,  F.  R.,  748. 


834 


INDEX 


Carpenter,  J.  A.,  297,  619. 

Carrara,  Italy,  164. 

Carroll  sand,  96. 

Carter,  T.  L.,  745. 

Cartersville,  Ga.,  315,  372,  751,  764. 

Carter,  W.  E.  H.,  68. 

Caspian  Sea,  211,  215. 

Cassiterite,  810. 

Castle,  Mont.,  767. 

Castle  Dome  district,  Ariz.,  330. 

Castle  Rock,  Colo.,  148. 

Catlett,  C.,  65,  209,  498. 

Caucasus,  Russia,  113. 

Cauldwell,  F.  W.,  768. 

Cave  Spring,  Ga.,  764. 

Cavities,  ore  deposits,  origin,  455. 

Cayeux,  L.,  556. 

Cazadero,  Calif.,  359. 

Cebolla  Creek,  Colo.,  520. 

Celestite,  392. 

Cement,  hydraulic,  188. 

hydraulic  lime,  189. 
natural  rock,  190. 
oxychloride,  360. 
plaster,  256. 
Portland,  191. 
pozzuolan,  188. 
production,  205. 
references  on,  207. 
Roman,  190. 
Rosendale,  190. 
slag,  189. 
uses  of,  205. 

Central  City,  Colo.,  702,  826. 
Cerargyrite,  676. 
Cerbat  Range,  Ariz.,  453. 
Ceresin,  126. 

Cerrillos  coal  field,  N.  Mex.,  16. 

Cerillos  Hills,  N.  Mex.,  5. 

Cerrillos,  N.  M.,  42. 

Cerro  de  Pasco,  Peru,  827. 

Cerro  de  Potosi,  Bolivia,  813. 

Cerussite,  622. 

Ceylon,  graphite,  349;  mica,  369;  topaz,  385. 

Chaffee  County,  Colo.,  671. 

Chalcanthite,  568. 

Chalcocite,  568. 

Chalcopyrite,  568. 

Chalk,  definition,  150. 

Chamberlin,  R.  T.,  441,  498. 

Chamberlin,  T.  C.,  209,  421,  566,  649,  657. 

Chapin,  T.,  818. 

Chara,  202. 

Charleston,  S.  C.,  266. 

Charpentier,  T.  F.  W.,  465. 

Charter  Towers,  Queensland,  706. 

Chatsworth,  Ga.,  407. 

Chattanooga,  Tenn.,  35,  751. 

Chauvenet,  R.,  564. 

Cheshire,  Mass.,  341. 

Chestnut  Yard,  Va.,  612. 

Chiapas,  Mex.,  686. 

Chichagof  Island,  Alas.,  253. 

Chile,  copper,  603;    nitre,  232. 

China,  antimony,  781;  coal,  52. 

China  clay,  176. 

Chloanthite,  795. 

Chorolque,  Bolivia,  787. 

Chromic  iron  ore,  analyses,  790. 
Canada,  791. 


Chromic  iron  ore,  foreign  deposits,  792. 
minerals,  789. 
production,  792. 
references  on,  793. 
United  States,  791. 
uses,  792. 
value  of  ores,  489. 
Chromite,  789. 
Chrysocolla,  568. 
Chrysotile,  298,  302. 
Chuquicamata,  Bolivia,  603. 
Cinnabar,  771. 
Cippolino  marble,  164. 
Cirkel,  F.,  306,  308,  353,  793. 
Clapp,  C.  H.,  68,  185,  202,  243,  620,  656. 
Clapp,  F.  G.,  88,  133,  135,  209,  421. 
Clarion  coal,  32. 
Clark,  J.  D.,  617. 
Clark,  W.  B.,  66,  208,  283. 
Clarke,  F.  W.,  65,   70,   133,   213,   228,   231, 
237,  259,  282,  318,  390,  400,  435,  497,  498, 
827. 

Clarksburg,  W.  Va.,  8. 
Clarion  County,  Pa.,  8. 
Clausthal,  Ger.,  467,  672." 
Clay,  analyses,  175. 

classification,  174. 
definition,  170. 
eolian,  172. 
flint,  176. 
floodplain,  171. 
for  cement,  191. 
foreign  deposits,  182. 
glacial,  172. 

geologic  distribution,  176. 
kinds  of,  176. 
lake,  171. 
marine,  171. 
production,  183. 
properties,  172. 
references  on,  184. 
residual,  170. 
shale,  171. 
transported,  170. 
United  States,  178. 
uses  of,  182. 
Clay  ironstone,  558. 
Clayton,  la.,  341. 
Clear  Lake,  Calif.,  233. 
Clements,  J.  M.,  565. 
Clendenin,  W.  W.,  185. 
Cleveland,  O.,  220,  222. 
Clifton,  Ariz.,  577. 
Clinton  ore,  age,  537. 

occurrence,  537. 
origin,  545. 
United  States,  537. 
Clinton  sand,  97. 
Cloverport  sand,  96. 
Coal,  Alaska,  46. 

anthracite,  5. 
Appalachian  field,  28. 
ash,  analyses  of,  10. 
ash  in,  6. 

associated  rocks,  22. 
bituminous,  2. 
blossom,  22. 
bone,  3. 
Canada,  47. 
cannel,  4.  36. 


INDEX 


835 


Coal,  classification,  18. 

coke,  natural,  5. 

coking,  4. 

delta  deposits,  12. 

Eastern  Interior  field,  35. 

faults  in,  24. 

fixed  carbon,  6. 

foreign  deposits,  52. 

fuel  ratio,  6. 

gas,  analysis  of,  79. 

geologic  distribution,  26. 

Gulf  province  lignites,  45. 

ingredients  of,  6. 

kinds  of,  1. 

lignite,  2. 

moisture  in,  6. 

Northern  Interior  field,  37. 

origin  of,  10. 

outcrops,  22. 

Pacific  coast  field,  45. 

peat,  defined,  X. 

Philippines,  52. 

pinches,  23. 

production,  52. 

proximate  analysis,  6. 

references  on,  65. 

reserves  of  world,  52. 

Rocky  Mountain  fields,  42. 

semianthracite,  4. 

slate  in,  23. 

smut,  22. 

Southwestern  field,  38. 

splits,  23. 

structural  features,  22. 

subbituminous,  2. 

sulphur  in,  10. 

swelling,  23. 

thickness  of  beds,  22. 

Triassic  field,  35. 

volatile  matter,  6. 

weathering  of,  25. 

Western  Interior  field,  38. 
Coaldale,  Nev.,  242. 
Coal  Harbor,  Alas.,  8. 
Coal  Hill,  Ark.,  9. 
Coalinga,  Calif.,  102. 
Coalville,  Utah,  8. 
Cobalt,  ore  minerals,  794. 

other  foreign  deposits,  803. 
production,  804. 
references  on,  805. 
United  States,  794. 
uses,  804. 

Cobalt-arsenopyrite,  795. 
Cobalt  bloom,  795. 
Cobaltite,  795. 

Cobalt-tourmaline  veins,  448. 
Cockeysville,  Md.,  153. 
Cody,  Wyo.,  397. 
Coeur  d'Alene,  Ido.,  660. 
Coffeen,  111.,  8. 
Coke,  4. 

natural,  5. 

Cokeville,  Wyo.,  276. 
Cole,  A.  A.,  749. 
Cole,  L.  H.,  229,  259. 
Coleman,  Alberta,  50,  51. 
Coleman,  A.  P.,  136,  296,  567,  796,  798,  805. 
Colemanite,  233. 
Coleraine,  Can.,  790. 


Colgate,  Okla.,  102. 
Colles,  G.  W.,  370. 
Collier,  A.  J.,  19,  65,  66,  619,  818. 
Colloids,  in  ores,  461. 
Collophanite,  261. 
Colombia,  platinum,  807. 
Colorado,  artesian     water,    418;     bismuth, 
786;  building  stone,    149;    cement,   202; 
clay,  180;   coal,  42;    copper,  573;  feldspar, 
323;   fluorspar,  329;   gilsonite,    122;   gold- 
silver,   702;    granite,    148;    gypsum,  252; 
iron,     516,     520;      lead-zinc,     630,    636; 
limonite,  552;    manganese,  767;    marble, 
153;  mica,  367;  oil  shale,  125;  onyx,  154; 
petroleum,   108;    potash,   242;    selenium, 
809;    silver-lead,  668,  671,  673;  tungsten, 
823;  uranium,  826;  vanadium,  826;   vol- 
canic ash,  290. 
Coloradoite,  771. 
Columbia,  Pa.,  341. 
Columbite,  810. 
Colville  basin,  Alas.,  48. 
Colvocoresses,  G.  M.,  803. 
Commentry,  France,  12,  23. 
Comstock  Lode,  Nev.,  718. 
Comstock,  T.  B.,  783. 
Condit,  D.  D.,  134,  337. 
Condra,  G.  C.,  422. 
Connate  water,  in  ore  formation,  438. 
Conneaut,  O.,  335,  336. 

Connecticut,  beryl,    383;     clay,    179;     dia- 
base,     148;      feldspar,     322;  sandstone, 
158;     tourmaline,  386;  vein  quartz,  391. 
Contact  metamorphic  deposits,  448,  473. 

classification,  452. 
copper,  573. 
gold-silver,  686. 
iron,  513. 
lead-zinc,  626. 
origin,  449. 
tin,  811. 

Cook,  C.  W.,  228,  230,  239. 
Cook,  G.  H.,  185,  283. 
Cooke,  H.  C.,  499,  620. 
Cook  Inlet,  Alas.,  48,  109. 
Cooper,  A.  S.,  134. 
Cooper,  C.  A.,  825. 
Coopers,  W.  Va.,  9. 
Cooper  sand,  96. 
Coosa  coal  field,  35. 
Coos  Bay  coal  field,  Ore.,  46. 
Copper,  Alaska,  588,  602,  613. 
antimony  in,  780. 
bismuth  in,  786. 
Canada,  590,  613. 
contact  metamorphic  deposits,  573. 
deposits  by  circulating  water,  592. 
deposits  in  schists,  610. 
foreign  deposits,  603. 
gangue  minerals,  569. 
hot  spring  deposits,  443. 
impurities  in  ores,  569. 
intermediate    vein    zone    deposits, 

593. 

lower  vein  zone,  592. 
magmatic  segregations,  572. 
meteoric  water  deposits,  609. 
native,  568. 

native,  deposits  of,  603. 
nickel  in,  796. 


836 


INDEX 


Copper,  occurrence,  569. 

ore  minerals,  568. 

origin,  569. 

other  foreign  deposits,  614. 

production,  615. 

references  on,  617. 

reserves,  617. 

secondary  enrichment,  485. 

superficial  alteration,  570. 

tellurium  in,  810. 

United  States,  572,  573,  592,  593, 
610. 

uses  of,  614. 

value  of  ores,  488. 

weathering  reactions,  480. 
Copper  Mountain,  Alas.,  588. 
Copperopolis,  Calif.,  692. 
Copperopolis,  Ore.,  593. 
Copper  Queen  Mine,  Bisbee,  Ariz.,  573. 
Copper  River,  Alaska,  109. 
Copper  River  district,  Alaska,  602. 
Coquina,  definition  of,  150. 
Core  sand,  334. 
Cornish  stone,  324. 
Cornwall,  Eng.,  182,  324,  816. 
Cornwall,  Pa.,  449,  512. 
Corocoro,  Bolivia,  609. 
Corundum,  analyses,  292. 
Canada,  294. 
occurrence,  292. 
preparation,  294. 
United  States,  293. 
Corundum  Hill,  N.  C.,  292. 
Coste,  E.,  80,  133. 
v.  Cotta,  B.,  497. 
Coulbeaux,  M.,  236. 
Coulters  station,  Utah,  118. 
Covellite,  568. 
Covington,  Va.,  557. 
Cow  Run  sand,  96. 
Cox,  C.  F.,  321. 
Cox,  E.  T.,  781. 
Cox,  G.  H.,  650,  656. 
Coxville,  Ind.,  341. 
Craig,  E.  H.  C.,  133. 
Cranbrook,  B.  C.,  659. 
Crane,  G.  W.,  564,  656,  666,  674. 
Crane,  W.  R.,  66,  134,  745. 
Crawford,  R.  D.,  746. 
Creede,  Colo.,  636,  673. 
Crenshaw,  J.  L.,  655. 
Crested  Butte,  Colo.,  9,  16,  42. 
Crider,  A.  F.,  185,  208,  422. 
Crimora,  Va.,  755. 
Cripple  Creek,  Colo.,  719,  810. 
Critical  level,  defined,  457. 
Crocidolite,  298. 
Crockett,  Tex.,  8. 
Crooks,  A.  R.,  794. 
Crosby,  W.  O.,  136,  185,  451,  497. 
Cross,  W-,  673,  746. 
Crows  Nest  Pass,  Can.,  50. 
Crump,  M.  H.,  136,  168. 
Gratification,  in  veins,  466. 
Cryolite,  332,  750. 
Cuba,  iron,  518,  558. 
Cullinan  diamond,  382. 
Culm,  31. 

Cumberland,  Eng.,  255,  548. 
Cumberland  Hill,  R.  I.,  521. 


Cumberland,  Md.,  191,  196. 
Cumberland,  N.  S.,  coal,  47. 
Cumenge,  E.,  745. 
Cummings,  U.,  207. 
Cummins,  W.  F.,  228. 
Cuprite,  568. 
Curie,  J.  H.,  745. 
Curtis,  J.  S.,  674. 
Cushman,  A.  S.,  243,  327. 
Cutters,  in  phosphate,  268. 
Cutter,  N.  Mex.,  826. 
Cuyuna  range,  Minn.,  532. 


Dachnowski,  A.,  69. 

Daggett,  Calif.,  233. 

Dahllite,  261. 

Dake,  C.  L.,  566. 

Dale,  T.  N.,  167,  168. 

Dalton,  L.  V.,  113,  133. 

Dammer,  B.,   125,    182,  255,  282,  316,  338, 

355,  362,  368,  400,  412,  755. 
Danville,  Ky.,  315. 
Que.,  306. 

Darton,  N.  H.,  168,  196,  228,  297,  334,  421. 
Daubree,  A.,  813. 
Davidson,  W.  B.  M.,  282. 
Davis,  C.  A.,  62,  64,  68,  69,  82. 
Davis,  N.  B.,  184. 
Davis,  coal,  32. 

Mass,  403. 

Day,  A.  L.,  217,  327,  441,  456,  485,  498,  501. 
Day,  D.  T.,  73,  85,  91,  94,  113,  133,  135, 

136,  340,  808,  809. 
Dead  Sea,  211. 
Deadwood,  B.  C.,  591. 
Death  Valley,  Calif.,  233. 
Decatur  County,  Ga.,  338. 
De  Golyer,  E.,  111.      ' 
De  Kalb,  C.,  169. 
De  La  Beche,  H.,  461. 
Delkeskamp,  R.,  500. 
Deming,  N.  M.,  329. 
Denmark,  flint,  295. 
Dennis,  L.  M.,  379. 
Derby,  O.  A.,  390,  548. 
Derbyshire,  Eng.,  332. 
Descloisite,  825. 
Detroit,  Mich.,  220. 
Deussen,  A.,  422. 
De  Wolf,  F.  W.,  100,  185. 
DeWolf,  W.  P.,  825. 
Dexter,  Kas.,  73. 
Diabase,  as  building  stone,  148. 
Diamond,  as  abrasive,  295. 

bort,  380. 

Canada,  382. 

carbonado,  380. 

origin,  382. 

properties,  380. 

South  Africa,  381. 

United  States,  381. 
Diaspore,  750. 
Diatomaceous  earth,  analyses,  319. 

foreign  deposits,  320. 
occurrence,  318. 
properties  of,  318. 
United  States,  320. 
uses,  320. 
Dick,  W.  J.,  283. 


INDEX 


837 


Dickinson,  H.  T.,  168. 

Dickson,  C.  W.,  316,  318,  799,  805. 

Diller,  J.  S.,  67,  297,  308,  412,  564,  746,  748, 

793. 
Dillon,  Kas,  253. 

Mont.,  349. 

Dismal  swamp,  Va.,  12. 
Disseminated  ore  deposits,  473. 
ores,  copper,  600. 
Dolbear,  C.  E.,  243. 
Dolbear,  S.  H.,  771,  793. 
Dole,  R.  B.,  243. 
Dolomite,  150. 
Domes,  salt,  217. 
Don,  J.  R.,  745. 
Donald,  J.  F.,  808. 
Doughty  Springs,  Colo.,  309. 
Douglas,  J.,  475,  620. 
Douglas  Island,  Alas.,  693,  694. 
Dow,  A.  W.,  136. 

Dowling,  D.  B.,  17,  21,  65,  68,  135. 
Downs,  W.  F.,  353. 
Dragoon,  Ariz.,  823. 
Drake,  N.  F.,  40. 
Dresser,  J.  A.,  307,  308,  412,  749. 
Drysdale,  C.  W.,  620. 
Ducktown,  Tenn.,  477,  478,  610. 
Duluth,  Minn.,  323. 
Dumble,  E.  T.,  67,  748. 
Dunkard  sand,  96. 
Dunmore,  Alberta,  115. 
Dunn,  E.  M.,  786,  788. 
Durham,  Eng.,  332. 
Durley,  R.  J.,  68. 
Dyscrasite,  772. 


Eagle  River,  Colo.,  671. 
Eak'le,  A.  S.,  747. 

Earth's  crust,  average  composition,  435. 
East  Broughton,  Que.,  306. 
Ebano,  Mex.,  111. 

Eckel,  E.  C.,  167,  207,  208,  209,  228,  250, 
259,  283,  297,  377,  564,    566,  746. 
Eddingfield,  F.  T.,  771. 
Edmonton,  Alberta,  111. 
Edwards,  M.  G.,  758. 
Egypt,  onyx,  154. 
Eilers,  A.,  788,  809,  810. 
Ekersund-Soggendal,  Nor.,  524. 
Elba,  Italy,  548. 

Eldridge,  G.  H.,  134,  136,  184,  283,  421. 
Elizabeth  sand,  97. 
Elk  garden  coal,  32. 
Elkhorn,  Mont.,  573,  686. 
Elk  sand,  97. 
Ellis,  E.  E.,  417. 
Elliston,  Mont.,  275. 
Ells,  R.  W.,  136,  282,  620. 
El  Oro,  Mex.,  730. 
Eluvial  placers,  434. 
Ely,  Nev.,  585. 
Embolite,  676. 
Embreeville,  Pa.,  323. 
Emerald,  383. 
Emerson,  B.  K.,  793. 
Emerson, -Ga.,  372. 
Emery,  analyses,  294. 

occurrence,  294. 


Emley,  W.  E.,  2O7. 

Emmons,  S.  F.,  441,  474,  482,  498,  499,  500, 

501,    592,   619,    634,   655,    673, 

746,  771. 
Emmons,  W.   H.,  334,  406,  443,  452,  457, 

477,   481,  499,   500,   617,   619, 

620,    655,   673,    677,    745,   746, 

747. 

Enargite,  568. 

England,  barite,  316;    clay,  182;    coal,  52; 
cornish  stone,  324;    feldspar,     324;  fluor- 
spar,  332;     fuller's   earth,   338;   gypsum, 
255;     iron,     548;    limestone,     164;    salt, 
225;   siderite,  559;    tin,  816. 
Englehardt,  F.  E.,  228. 
Engler,  C.,  81. 
Eno,  F.  H.,  207,  208. 
Enstatite,  source  of  talc,  408. 
Eosine,  229. 

Epigenetic  ore  deposits,  434. 
Epperson  sand,  96. 
Erythrite,  795. 
Erzberg,  Styria,  548. 
Estelle,  Ga.,  371. 
Estevan,  Sask.,  51. 
Eton,  Ga.,  315. 
Euboea,  Greece,  356. 
Eureka,  Nev.,  434,  671. 
Everett,  Wash.,  784. 
Evergreen,  Colo.,  329. 
Everton,  Ark.,  341. 


Fahlband,  472. 
Fairbanks,  Alas.,  735. 
Fairbanks,  H.  W.,  321,  746. 
Fairburn,  S.  Dak.,  338. 
Fairview,  111.,  333. 
Fallen,  Nev.,  242. 
Falun,  Swe.,  573. 
Faribault,  E.  R.,  705,  825. 
Farrell,  J.  H.,  497. 
Farrington,  O.  C.,  390. 
Fawns,  S.,  818. 
Fay,  A.  H.,  318,  818. 
Feldspar,  analyses,  323. 

Canada,  324. 

commercial  grades,  326. 

England,  324. 

occurrence,  321. 

production,  324. 

properties,  321. 

references  on,  327. 

United  States,  322. 

uses,  324. 

Felsobanya,  Hungary,  729. 
Fenneman,  N.  M.,  134,  135. 
Fenner,  C.  N.,  499,  592. 
Ferberite,  822. 
Fergus  County,  Mont,  385. 
Ferguson,  H.  G.,  501,  812,  818. 
Ferguson,  Okla.,  224. 
Fermor,  L.  L.,  758,  768. 
Fernekes,  G.,  618. 
Ferrier,  W.  F.,  283. 
Ferromanganese,  768. 
Fertilizers,  apatite,  260. 

greensand,  279. 
guano,  279. 
kainite,  260. 


838 


INDEX 


Fertilizers,  nelsonite,  260. 

phosphate  of  lime,  260. 
potash,  238. 
production,  280. 
See   Phosphates, 
uses,  279. 

Fieldner,  A.  C.,  65. 
Fifth  sand,  97. 
Fifty-foot  sand,  96. 
Finch,  J.  W.,  500. 
Finland,  granite,  146;    platinum,  805;    tin, 

811. 

Finlayson,  A.  M.,  485,  486,  498,  614,  729. 
Fisher,  C.  A.,  186,  422. 
Fitch,  R.  S.,  825. 
Five  Islands,  N.  S.,  315,  316. 
Flagstone,  158. 
Flat  Run  sand,  97. 
Flat  Top  coal  field,  34. 
Fleck,  H.,  825,  827. 
Flint,  391. 

clay,  176. 
pebbles,  295. 
Florence,  Colo.,  83,  108. 
Florida,  clay,  180;  fuller's  earth,  338:  peat, 

8;  phosphate,  263. 
Fluorite.     See  Fluorspar. 
Fluorspar,  analyses,  333. 
Canada,  332. 
foreign  deposits,  332. 
occurrence,  327. 
origin,  329. 
production,  333. 
properties,  327. 
references  on,  334. 
United  States,  327. 
uses,  332. 

Foerste,  A.,  185,  283. 
Fohs,  F.  J.,  66,  318,  334. 
Foothills  belt,  Calif.,  613. 
Forstner,  W.,  134,  778. 
Fort  Defiance,  Ariz.,  384. 
Fort  Dodge,  la.,  250,  253. 
Fort  Scott,  Kas.,  190,  197. 
Forty  Mile  Creek,  Yukon,  693. 
Foundry  sands,  analyses  of,  335. 
definition,  334. 
physical  tests,  336. 
production,  337. 
references,  337. 
requisite  properties,  335. 
United  States,  337. 
Fourche  Mountain,  Ark.,  120. 
Fox,  R.  W.,  499. 
Fraleck,  E.  L.,  404. 

France,  antimony,  781;    barite,  316;    baux- 
ite, 755;   bismuth,  787;   bituminous  rock, 
124;  buhrstone,  284;   coal,  52;  flint,  295; 
gypsum,  255;   hydraulic  lime,  189;  iodine, 
237;    kaolin,  182;    limestone,  164;  limon- 
ite,  556;    marble,   153;    phosphate,  280; 
salt,  225;   talc,  410;  tuff  for  building,  164. 
Frank,  Alberta,  50. 
Franklinite,  621,  759. 
Frazer  delta  coals,  Brit.  Col.,  12. 
Frazer,  P.,  4,  19,  65. 
Fredericktown,  Mo.,  147,  795. 
Free,  E.  E.,  243. 
Freeport,  Pa.,  229. 
Freestone,  158. 


Freiberg,  Sax.,  462,  672,  826. 

Freibergite,  676. 

French  Broad  district,  N.  C.,  315. 

Fuchs,  E.,  497,  781. 

Fuel  ratio,  coal,  6,  19. 

Fuller,  M.  L.,  419,  421,  438. 

Fuller's  earth,  analyses,  338. 

foreign  deposits,  338. 

production,  339. 

properties,  337. 

references,  340. 

United  States,  338. 

uses,  339. 


Gabbro,  for  building,  148,  149. 

Gadsden  County,  Fla.,  338. 

Gaffney,  S.  C-,  811,  814. 

Gale,  H.  S.,  228,  231,  235,  237,  243,  283, 
362, 619, 809, 827. 

Galena,  622. 

Galicia,  ozokerite,  118;  petroleum,  113; 
salt,  225. 

Galleys,  N.  Mex.,8. 

Gallup,  F.  L.,  337. 

Galpin,  S.  L.,  184,  327,  370,  751,  758. 

Gangue  minerals,  429. 

Gantz  sand,  96. 

Gardner,  J.  H.,  67,  185. 

Garfias,  V.  R.,  Ill,  133. 

Garnet,  as  gems,  383. 

occurrence,  291. 
United  States,  291,  383. 
uses,  291. 

Garnierite,  795. 

Garrey,  G.  H.,  592,  747. 

Garrison,  F.  L.,  498,  566. 

Gary,  W.  Va.,  9. 

Gases,  magmatic,  444. 

Gas  sand,  96. 

Gas.     See  Natural  Gas. 

Gaston  County,  N.  C.,  315. 

Gautier,  A.,  500. 

Gaylussite,  242. 

Geijsbeek,  S.,  184. 

Gellivare,  Sweden,  517,  518,  519. 

Gem,  Ido.,  660. 

Gems.     See  Precious  Stones. 

Genthite,  795. 

George,  R.  D.,  108,  746,  825. 

Georgetown,  Colo.,  702. 
Ido.,  276! 
Me.,  323. 

Georgia,  asbestos,  300;  barite,  315;  baux- 
ite, 751;  clay,  179,  180;  corundum,  293; 
fuller's  earth,  338;  gold,  691;  granite, 
147;  graphite,  349;  hydraulic  lime,  189; 
manganese,  761,  764,  marble,  153;  mica, 
368;  mineral  paint,  371;  natural  cement 
rock,  196;  ocher,  372;  phosphate,  278; 
pyrite,  403;  serpentine,  156;  slate,  162; 
talc,  409. 

Georgian  Bay,  Can.,  111. 

German  silver,  652,  804. 

Germany,  barite,  316;  bauxite,  755;  bis- 
muth, 787;  buhrstone,  286;  cadmium, 
788;  clay,  179;  coal,  52;  cobalt,  803; 
copper,  603,  605,  609;  fluorite,  332;  ful- 
ler's earth,  338;  hydraulic  lime,  189; 


INDEX 


839 


Germany,  kaolin,  182;   limonite,  556;  litho- 
graphic stone,  355;  salt,  225;  silver-lead, 
672;  tin,  811;    zinc,  651. 
Gersdorffite,  795. 
Gibbsite,  750. 
Gibson,  A.  M.,  66. 
Gilbert,  G.  K.,  231,  421. 
Gillette,  H.  P.,  499. 
Gilpin  County,  Colo.,  704. 
Gilpin,  J.  C.,  340. 
Gilsonite,  121,  126. 
Glasser,  M.  E.,  803. 
Glass  sand,  analyses,  341. 

composition,  340. 
mechanical  analyses,  342. 
physical  properties,  341. 
production,  343. 
references,  343. 
United  States,  342. 
Glauber  sa'lt.     See  Sodium  Sulphate. 
Glendale,  Mont.,  671. 
Glendive,  Mont.,  8. 
Glendon,  N.  C.,411. 
Glenn,  L.  C.,  67,  414,  421,  500. 
Glenravel,  Ireland,  751. 
Glens  Falls,  N.  Y.,  192. 
Globe,  Ariz.,  301,  600. 
Godfrey,  Ont.,  305. 
Golconda,  Xev.,  767. 
Gold,  dredging,  734. 

fissure  veins,  types  of,  676. 
hot  spring  deposit,  442. 
occurrence,  mode  of,  676. 
ore  minerals,  675. 
placers,  730. 

solution  in  weathering,  480. 
uses  of,  737. 
value  of  ores,  488. 
Goldfield,  Nev.,  708,  713. 
Gold-silver  ores,  Black  Hills  region,  684. 
Canada,  705. 
classification,  678,  680. 
contact  metamorphic,  686. 
copper  bearing,  679. 
Cordilleran  region,  681. 
Cretaceous-Tertiary,    682. 
deep  vein  zone,  686. 
dry  or  siliceous,  679. 
Eastern    crystalline    belt, 

685. 

extraction,  680. 
foreign  deposits,  705,  729. 
free-milling  ores,  680. 
geologic  comparisons,  685. 
geologic  distribution,  678. 
intermediate  depth,  695. 
lead  bearing,  680. 
placers,  678,  730. 
production,  738. 
refractory  ores,  680. 
secondary          enrichment, 

677. 

seleniferous,  729. 
shallow  depth,  708. 
siliceous,  679. 
Tertiary  veins,  684. 
United    States,    681,    686, 

695,  708. 

weathering  of,  677. 
zinc  ores,  680. 


Gordon,  C.  H.,  134,  168,  566,  619,  656,  748, 

Gordon  sand,  97. 

Goroblagoclat,  Russia,  518. 

Gosling,  E.  B.,  136. 

Gossan,  476.. 

Gossan  Lead,  Va.,  611,  612. 

Gothite,  503. 

Gottschalk,  V.  H.,  478,  501. 

Gouge,  468. 

Gould,  C.  N.,  134,  136,  168,  228,  259,  422, 

Gouverneur,  N.  Y.,  153,  403. 

Grabau,  A.,  213,  217,  228,  247,  259. 

Grahamite,  118. 

Grain,  in  granite,  144. 

Grande  Cote,  La.,  223. 

Grand  Etang  Harbor,  N.  S.,  253. 

Grand  Rapids,  Mich.,  250,  253. 

Granite,  Canada,  162. 

for  building,  144. 
United  States,  146. 
uses  of,  148. 

Grant,  U.  S.,  620,  657,  747,  748. 
Grape  Creek,  Colo.,  521. 
Graphite,  amorphous,  34"4. 

analyses,  344,  348. 

Canada,  349. 

crystalline,  344. 

foreign  deposits,  349. 

industry,  351. 

occurrence,  345. 

origin,  345. 

production,  352. 

properties,  344. 

references,  353. 

uses,  351. 

Grass  Valley,  Calif.,  696. 
Grasty,  J.  S.,  208,  318. 

Graton,  L.  C.,  452,  456,  485,  499,  565,  617, 
618,  619,  656,  674,  691,  747,  748, 
818,  819. 

Grays  Summit,  Mo.,  341. 
Great  Gossan  Lead,  Va.,  550. 
Great  Plains,  Can.,  coal,  50. 
Great  Salt  Lake,  Utah,  211,  226. 
Greece,  magnesite,  356;    marble,  153,  164; 

lead-silver,  673. 
Greenland,  cryolite,  332,  750. 
Greenockite,  641,  788. 
Green  River  coal  basin,  Wyo.,  42. 
Green  River,  Utah,  826. 
Greensand,  analyses,  279. 

occurrence,  279. 
Greensboro,  N.  C.,  521. 
Greenville,  Va.,  557. 
Gregory,  H.  E.,  167,  392,  421,  498. 
Gregory,  J.  W.,  737. 
Greisen,  812. 
Greisenization,  488. 
Grimsley,  G.  P.,   168,   186,  208,  209,  228, 

230,  259,  297,  343,  564. 
Griqualand,  Africa,  307. 
Griswold,  L.  S.,  134,  297. 
Griswold,  W.  T.,  84,  95. 
von  Groddeck,  A.,  451. 
Grossularite,  290. 
Ground  water,  composition,  442. 
Grout,  F.  F.,  20,  60,  66,  185,  186,  434,  499, 

619. 

Grubenmann,  A.,  457. 
Guanajuato,  Mex.,  730,  813. 


840 


INDEX 


Guano,  279. 
Gulf  of  Suez,  216. 
Gumbo,  176. 
Gunther,  C.  G.,  497. 
Gypsite,  244,  248. 

analyses  of,  253. 
Gypsum,  analyses,  253. 

calcining  of,  256. 

Canada,  253,  254. 

difference  from  anhydrite,  246. 

earth,  248. 

foreign  deposits,  255. 

geologic  distribution,  249. 

gypsite,  248. 

impurities  in,  246. 

occurrence,  244. 

origin,  246. 

production,  256. 

properties,  244. 

United  States,  249. 

uses,  255. 
Gypsumville,  Man.,  253. 

H 

Haenig,  A.,  353. 
Hafer,  C.,  771. 
Hager,  D.,  133. 
Hager,  L.,  218. 
Hague,  A.,  500,  674. 
Hahn,  F.  F.,  228. 
Haile  Mine,  S.  C.,  691. 
Hainesport,  N.  J.,  336. 
Hale,  D.  J.,  208. 
Haley,  D.  F.,  783. 
Halifax,  Mass.,  8. 
Hall,  J.,  545. 
Hamilton,  N.  D.,  25,  65. 
Hancock,  Md.,  190,  196. 

W.  Va.,  341. 
Hanna,  G.  B.,  747. 
Hanover,  N.  J.,  341. 

N.  M.,  788. 
Harder,  E.  C.,  452,  513,  548,  565,  566,  695, 

758,  768,  771,  793. 
Hardin  County,  111.,  328. 
Hardman,  J.  E.,  567. 
Hardwick,  Vt.,  145. 
Harker,  A.,  446. 
Harkins,  W.  D.,  788. 
Harney  Peak,  S.  Dak.,  815. 
Harris,  G.  D.,  66,  133,  134,  136,  217,  223, 

228,  396,  421. 
Hartford,  W.  Va.,  229. 
Hartnagel,  C.  A.,  566. 
Hartshorne  coals,  41. 
Hartville  district,  Wyo.,  536. 
Hastings  County,  Ont.,  292,  298. 
Hastings,  J.  B.,  500,  501. 
Hatch,  F.  A.,  695,  737. 
Hatscheck,  E.,  499. 
Hauraki,  N.  Z.,  729. 
Hauteville,  France,  164. 
Haworth,  E.,  66,   134,   135,  208,  228,  421 

645,  656. 

Hayes,  A.  O.,  567. 
Hayes,  C.  W.,  65,  66,  67,  136,  283,  318,  377, 

497,  566,  752,  754,  758,  771. 
Hazeltine,  R.,  66,  67. 
Headden,  W.  P.,  309. 


Hedley,  Brit.  Col.,  449,  686,  687. 

Heikes,  V.,  745. 

Helena,  Mont.,  629. 

Helen  Mine,  Ont.,  pyrite,  404. 

Hematite,  503. 

foreign  deposits,  517. 

Lake  Superior  region,  525. 

paint,  371. 

United  States,  524. 
Henegar,  H.  B.,  318. 
Henryton,  Md.,  323. 
Herald,  F.  A.,  259. 
Herkimer,  N.  Y.,  319. 
Herrick,  C.  L.,  259. 
Hershey,  O.  H.,  673. 
Herstein,  B.,  243. 

Hess,  F.  L.,  259,  353,  362,  400,  746,  780, 
783,  784,  786,  788,  794,  809,  810, 
818,  819,  822,  825,  827 
Heusler's  alloys,  768. 
Hewett,  D.  F.,  297,  321,  400,  748,  827. 
Hice,  R.  R.,  67,  168,  209,  565. 
Hicks,  W.  B.,  243. 
Hill  End,  N.  S.  W.,  706. 
Hill,  J.  M.,  619,  704,  746,  747. 
Hill,  R.  T.,  182,  217. 
Hillebrand,  W.  F.,  778,  809,  827. 
Hills,  R.  C.,  746. 
Hills,  V.  G.,  825. 
Hindostan  stone,  287. 
Hinds,  H.,  66. 
Hirschwald,  J.,  167. 
Hitchcock,  C.  H.,  68,  185. 
Hobbs,  W.  H.,  390,  566,  825. 
Hocking  Valley  coal,  32. 
Hodge,  E.  T.,  500. 
Hodges,  Jr.,  A.  D.,  805. 
Hoeing,  J.  B.,  134,  136. 
Hoen,  A.  B.,  355. 
H6fer,  A.,  81,  87,  133. 
Hoffman's  blue,  229. 
Holden,  R.  J.,  565. 
Holland,  T.  H.,  758. 
Holston,  Va.,  222. 
Homestake  Mine,  S.  Dak.,  690. 
Hook,  J.  S.,  283. 
Hopkins,  O.  B.,  308. 
Hopkins,  P.  E.,  748. 

Hopkins,  T.  C.,  167,  186,  327,  412,  414,  566. 
Hopper,  W.  E.,  124,  136. 
Horseneck  sand,  96. 
Horton  sand,  96. 
Horwood,  C.  B.,  737. 
Hoskins,  A.  J.,  370. 
Houghton,  Mich.,  606. 
Hovey,  E.  O.,  136,  414. 
Howes  Cave,  N.  Y.,  190. 
Hoyt,  S.  L.,  658. 
Huasteca,  Mex.,  111. 
Hubbard,  G.  D.,  134. 
Hubbard,  L.  L.,  228. 
Hiibnerite,  822. 
Hudson,  J.  G.  S.,  68. 
Huelva,  Spain,  404. 
Humboldt,  A.,  79. 
Humphreys,  R.  L.,  167,  207. 
Hundred  foot  sand,  96. 
Hungary,  gold-silver,  729;   iron,  518. 
Hunt,  T.  S.,  81,  87,  395. 
Hunt,  W.  F.,  400. 


INDEX 


841 


Hunter,  J.  F.,  400,  746. 

Huntington,  Ark.,  8. 

Huntley,  L.  G.,  70,  91,  111,  116,  135. 

Hurry  Up  sand,  96. 

Hutchinson,  L.  L.,  134,  136 

Hydatogenesis,  446. 

Hydrargillite,  751. 

Hydraulic  cements,  188.' 

lime,  189. 

limestone,  150. 
Hydrozincite,  621. 
Hypogene,  481. 


I 

Ichthyol,  126. 

Idaho,  asbestos,  302;    gypsum,  252;    phos- 
phate, 275;   silver-lead,  660. 
Idaho  Springs,  Colo.,  443,  702. 
Iditarod,  Alas.,  736. 
Idria,  Austria,  775. 

Illinois,  clay,  179,  180;    coal,  37;  fluorspar, 
328;     glass    sand,    342;     lead-zinc,    648; 
natural  cement  rock,  196;   petroleum,  99; 
pyrite,  403,    tripoli,  413. 
Ilmenite,  819. 

Impregnations  of  ores,  473. 
Impsomite,  120. 

India,  diamond,  295;    gold,  695;    mangan- 
ese, 768;    salt,  225. 

Indiana,  cement,  202;   clay,  179,  180;   coal, 
36;    foundry  sand,  337;    glass  sand,  343; 
limestone,  150;    natural  gas,  114;    petro- 
leum, 99;    pyrite,  403;    whetstones,  287. 
Indicators,  Ballarat,  706. 
Ingalls,  W.  R.,  655,  656. 
Inverness,  N.  S.,  24,  47. 
d'Invilliers,  E.  V.,  67,  343,  545. 
Iodine,  Chili,  237. 

in  phosphate,  237. 
seaweeds,  237. 
Silesian  zinc  ore,  237. 
sources,  237. 
lodyrite,  676. 
Iowa,   clay,    180;    coal,   38;    gypsum,  250; 

lead-zinc,  648;   limonite,  556. 
Irelan,  W.,  208. 
Ireland,  bauxite,  755. 
Iridium,  808. 
Iridosmine,  805. 

Iron  Mountain,  Wyo.,  520,  521,  522. 
Iron  Ores,  Canada,  524,  546. 
classification,  504. 
contact-metamorphic      deposits, 

513. 

foreign,  517,  548,  556,  559. 
hematite,  524. 
impurities  in,  503. 
limonite,  548. 

magmatic  segregations,  517. 
magnetite  sands,  523. 
minerals,  502. 
production,  559. 
pyrite,  559. 
references  on,  564. 
reserves,  563. 
siderite,  558. 
United  States,  505,  520,  524,  537, 

549. 
weathering,  479. 


Iron  Springs,  Utah,  512. 

Irvine  oil  sand,  97. 

Irving,  J.  D.,  486,  499,  501,  603,  656,  673, 
746,  748,  771,  825. 

Irving,  R.  D.,  466,  565,  619. 

Italy,  antimony,  781;  barite,  316;  bitumi- 
nous rock,  125;  iron,  548;  marble,  164; 
mercury,  775;  pumice,  288,  sulphur, 
398;  talc,  410;  tufa,  150. 

Ithaca,  N.  Y.,  220. 

Ivanhoe,  Va.,  551. 

Ivigtut,  Greenland,  332. 


Jack,  621. 

Jackson,  A.  W.,  167. 

Jackson,  Mich.,  336. 

Jacobs,  E.  C.,  412. 

Jacquet,  J.  B.,  659. 

Jagerfontein,  Orange  Colony,  382. 

Jamestown,  Colo.,  329,  333. 

Jamesville,  N.  Y.,  190. 

Jamison,  C.  E.,  135. 

Japan,  antimony,  781;    coal,  52;    sulphur, 

393. 

Jarvis,  R.  P.,  566. 
Jasper,  526. 

Jasperoid,  Missouri,  642. 
Jefferson  County,  Mont.,  671. 
Jeffrey,  E.  C.,  12,  65,  82. 
Jellico  district,  Tenn.,  35. 
Jenney,  W.  P.,  645,  656. 
Jennings,  La.,  107. 
Jerome  district,  Ariz.,  611. 
Jet,  defined,  2. 

Joachimsthal,  Austria,  787,  803,  826. 
Joggins,  N.  S.,  coal,  47. 
Johannesburg,  S.  Afr.,  737. 
Johanngeorgenstadt,  Sax.,  787,  826. 
Johnson,  B.  L.,  618. 

Johnson,  D.  W.,  5,  67,  91,  116,  390,  421. 
Johnson,  H.  R.,  231. 
Johnson,  R.  H.,  91,  133. 
Johnson,  R.  P.,  70. 
Johnston,  R.  A.  A.,  825. 
Johnston,  W.  D.,  184. 
Johnstown,  Pa.,  8. 
Jones,  Jr.,  E.  L.,  619,  746. 
Jones,  J.  C.,  259,  566. 
Jones,  R.  H.,  308. 
Jones  sand,  96. 
Joplin  Area,  Mo.,  640. 
Joseph,  M.  H.,  809,  825. 
Josephinite,  806. 
Julien,  A.  A.,  144,  167. 


K 


Kalgoorlie,  W.  Austral.,  695. 

Kalmus,  H.  T.,  805. 

Kame  sand,  97. 

Kamiah,  Ido.,  302. 

Kanawha,  W.  Va.,  226. 

Kanolt,  C.  W.,  756. 

Kansas,    cement,    202;     coal,    40;     natural 

cement    rock,    197;     gypsum,    248,    252; 

natural   gas,    115;     petroleum,    102;  salt, 

222. 

Kansas  City,  Kas.,  39. 
Kaolin,  analysis,  178. 


842 


INDEX 


Kaolin,  Europe,  182. 

Kapnick,  Hungary,  729. 

Karaboghaz  Gulf,  211,  215,  216. 

Katalla  field,  Alas.,  109. 

Katz,  F.  J.,  745. 

Kay,  G.  F.,  805. 

Kedzie,  G.  E.,  673. 

Keele,  J.,  186,  749. 

Keenburg,  Tenn.,  751,  754. 

Keener  sand,  96. 

Keene's  cement,  252,  256. 

Keith,  A.,  412,  512,  565,  656. 

Kellogg.  L.  O.,  746,  825. 

Kemp,  J.  F.(  237,  306,  308,  353,  400,  440, 
441,  451,  472,  489,  497,  499,  500, 
501,  512,  518,  520,  558,  565,  592, 
618,  619,  620,  628,  656,  745,  805, 
808. 

Kenmore,  O.,  220. 

Kennedy,  W.,  566. 

Kentucky,  barite,  313;  bituminous  rock, 
124;  clay,  180;  coal,  37;  fluorspar,  327; 
foundry  sand,  337;  guano,  279;  limonite, 
556;  lithographic  stone,  355;  natural 
cement  rock,  197;  natural  gas,  114;  phos- 
phate, 278;  siderite,  559 ;  whiting,  376. 

Kermesite,  780. 

Kern  County,  Calif.,  122. 

Kern  River,  Calif.,  102. 

Kern  River  field,  Calif.,  104. 

Kerosene  shale,  125. 

Ketchikan  district,  Alas.,  588. 

Keyes,  C.  R.,  237,  677,  745,  747. 

Kieselguhr,  318. 

Kiesente,  214. 

Killas,  816. 

Kimball,  E.  B.,  807. 

Kimball,  J.  P.,  564,  748. 

Kimberley,  S.  Af.r.,  382. 

Kindle,  E.  M.,  297.  566. 

King,  F.  H.,  437. 

King,  F.  P.,  296. 

Kingsgate,  N.  S.  W.,  788. 

Kingston,  Ont.,  324. 

Kirchoffer,  W.  G.,  422. 

Kirk,  C.  T.,  619. 

Kirksville,  Mo.,  9. 

Kiruna,  Sweden,  517,  519. 

Kithil,  K.  L.,  827. 

Klockman,  F.,  451,  497,  603,  614. 

Klondike,  Alas.,  735. 
Mo.,  341. 

Knight,  C.  W.,  308,  493,  498,  567,  800,  805. 

Knight,  W.  C.,  135,  168,  186,  231,  259,  422, 
748. 

Knopf,  A.,  448.  452,  618,  673,  674,  778,  806, 
809,  818. 

Knox  County,  Me.,  573. 

Kohler,  E.,  499. 

Kolar  gold  field,  India,  695. 

Koontz  coal,  32. 

Kootenay  district,  B.  C.,  671.- 

Korea,  graphite,  351. 

Kragero,  Norway,  819,  821. 

Kramer,  G.,  81. 

Kramm,  H.  E.,  259,  771. 

Kraubat,  Styria,  792. 

Krusch,  P.,  447,  497,  499,  524,  548,  569, 
672,  673,  705,  708,  729,  730,  775, 
803,  811,  816. 


Kubel,  S.  J.,  355. 

Kummel,  H.  B.,  185,  208,  343 

Kunz,  G.  F.,  390. 

Kunzite,  385. 

Kwinitza,  B.  C.,  225. 

Kyshtim,  Russia,  614. 


Lacroix,  A.,  758. 
Lafayette,  Colo.,  8. 
Lake  Abitibi,  Ont.,  694. 
Lake  Ainslie,  N.  S.,  315,  316. 
Lake  beds.     See  Potash,  239. 
Lake  Charles,  La.,  396. 
Lake  City,  Colo.,  636,  673. 
Lake  Larder,  Ont.,  694. 
Lake,  Mono,  211. 
Lake  of  the  Woods,  Ont.,  694. 
Lakes,  A.,  167. 
Lake  Sanford,  N.  Y.,  521. 
Lake  Tahoe,  211. 
Lake  Umbagog,  N.  H.,  319. 
Lake  Valley,  N.  M.,  671. 
Lamp  black,  116. 
Lancashire,  Eng.,  548. 
Lancaster,  Pa.,  432. 
Landes,  H.,  68,  135,  209. 
Land  pebble,  phosphate,  266. 

plaster,  256. 
Lane,  A.  C.,  37,  66,  208,  220,  228,  230,  247, 

422,  440,  500,  608,  618,  619. 
Laney,  F.  B.,  168,  619,  620,  747. 
Larcombe,  C.  O.  G.,  695. 
Laredo,  Tex.,  45. 
Larsen,  E.  S.,  243,  334,  400,  447,  500,  501, 

655,  673,  746. 
von  Lasaulx,  A.,  395. 
Latouche  Island,  Alas.,  613. 
de  Launay,  L.,  435,  438,  482,  497,  498,  614, 

745,  787. 
Laur,  F.,  758. 
Laurium,  Greece,  673. 
Lautarite,  237. 
Lawrenceville,  N.  Y.,  190. 
Lawson,  A.  C.,  451,  497,  586,  619. 
Layman,  F.  E.,  208. 
Lead,  cadmium  in,  788. 
desilverized,  624. 
ore  minerals,  622. 
production,  652. 
secondary  enrichment,  486. 
United  States,  638. 
uses,  651. 
value  of  ores,  488. 
Lead,  S.  D.,  690. 
Leadville,  Colo.,  630,  767. 
Lead-zinc  ores,  contact    metamorphic    de- 
posits, 626. 
foreign  deposits,  650. 
high-temperature  veins,  629 
intermediate  depth,  630. 
occurrence,  622. 
origin,  623. 
production,  652. 
references  on,  655. 
sedimentary  rock  deposits, 

636. 
shallow  depth  ores,  636. 


INDEX 


843 


Lead-zinc  ores,   United    States,    624,    626, 

648. 

weathering,  623. 
Le  Conte,  J.,  438,  778. 
Lee,  Mass.,  153. 
Lee,  W.  T.,  353,  400,  421. 
Lehigh,  N.  D.,  8. 

Okla.,  9. 

Lehigh  Valley,  Pa.,  192,  198. 
Leighton,  H.,  184,  259. 
Leith,  C.  K.,  451,  452,  497,  513,  534,  548, 

558,  564,  565,  619,  695,  771. 
Lenher,  V.,  745. 
Leonard,  A.  G.,  67,  656. 
Lepidolite,  354. 

Le  Roy,  O.  E.,  590,  593,  620,  674. 
Lesher,  C.  E.,  67. 
Lesley,  J.  P.,  65,  67,  168. 
Lesquereux,  L.,  65,  81,  84. 
Lester,  Ark.,  8. 
Lethbridge,  Alberta,  50. 
Leverett,  F.,  421,  422. 
Lewis,  J.  V.,  168,  390,  434,  619,  793. 
Lewiston,  Pa.,  341. 
Lignite,  analyses,  8. 
Canada,  49. 
properties  of,  2. 
Lignitoid,  14. 
Lima,  O.,  71. 
Lime,  187. 

hydraulic,  189,  194. 
properties  of,  188. 
raw  materials  (U.  S.),  193. 
references  on,  207. 
sand,  96. 
uses  of,  205. 

Limestones,  analyses  of,  187. 
Canada,  164. 
changes  in  burning,  188. 
characteristics,  149. 
compositions,  187. 
for  building,  149. 
United  States,  150. 
uses,  154. 
varieties  of,  149. 
Limmer,  Ger.,  124. 
Limnetic  coals,  13. 
Limonite,  503. 

Canada,  556. 
foreign  deposits,  556. 
gossan  deposits,  550. 
mountain  ores,  553. 
Oriskany,   555. 
residual  clay,  552. 
residual  deposits,  549. 
origin,  554. 

types  of  deposits,  549. 
United  States,  549. 
valley  ores,  553. 

Lincoln,  F.  C.,  441,  498,  618,  745. 
Lincolnton,  N.  C.,  815. 
Lindeman,  E.,  567. 
Lindemuth,  J.  R.,  243. 

Lindgren,  W.,  436,  440,  441,  443,  447,  451, 
452,  456,  457,  474,  489,  493, 
497,  498,  499,  501,  518,  574, 
603,  618,  619,  620,  656,  674, 
695,  737,  745,  746,  747,  748, 
778,  786,  809,  825. 
Lines,  E.  F.,  208. 


Linnaeite,  795. 

Linton,  111.,  9. 

Lipari  Islands,  290. 

Lithographic  stone,  analyses,  354. 

properties,  354. 

references,  355. 

sources,  355. 
Litharge,  651. 
Lithium,  354. 
Lithophone,  317,  652. 
Little  Cottonwood  Canon,  Utah,  668. 
Little  Rock,  Ark.,  148. 
Little  Rocky  Mountains,  Mont.,  453. 
Livermore,  Calif.,  767. 
Locke,  A.,  747. 
Lode,  denned,  471. 
Loess,  176. 
Logan,  W.  N.,  185. 
Lompoc,  Calif.,  319. 
Lopez,  Pa.,  9. 
Lord,  E.,  747. 
Lord,  N.  W.,  65,  67,  208. 
Los  Angeles,  Calif.,  101,  102. 
Lost  Hills,  Calif.,  102. 
Lost  River,  Alas.,  811. 
Louderback,  G.  D.,  390. 
Loughlin,  G.  F.,  185,  674,  825. 
Louisa  County,  Va.,  401. 
Louisiana,  limonite,  556;    natural  gas,  115; 
petroleum,  106;    salt,  217,  223;    sulphur, 
396. 

Louisville,  Ky.,  190,  197. 
Lowe,  E.  N.,  565,  566. 
Lowell,  Vt.,  299. 
Lower  Kittanning  coal,  32. 
Low  Moor,  Va.,  557. 
Lucas,  A.  F.,  133. 
Ludington,  Mich.,  220. 
Lumberton,  N.  J.,  335,  336. 
Lundbohm,  H.,  518. 
Luossavaara,  Swe.,  517. 
Lupton,  C.  T.,  135. 
Luxembourg,  limonite,  556;   iron,  558. 
Luzenach,  France,  409. 
Lyell,  C.,  65. 
Lyman,  B.  S.,  620. 
Lyon  Mountain,  N.  Y.,  511. 


M 


Mabery,  C.  F.,  133. 

McAdamite,  756. 

MacAlister,  D.  A.,  497. 

McCalley,  H.,  66,  566. 

McCallie,  S.  W.,  66,  167,  283,  421,  546,  566, 

746. 

McCarty,  E.  T.,  686. 
McCaskey,  H.  D.,  619,  778. 
McConnell,  R.  G.,  567,  620,  749. 
McCourt,  W.  E.,  68,  167. 
McCreath,  A.  S.,  565. 
McDonald,  P.  B.,  825. 
McFarland,  D.  F.,  73. 
MacFarlane,  J.,  65,  67. 
MacFarlane,  T.  M.  M.,  390. 
Mackenzie,  G.  C.,  567. 
McKittrick,  Calif.,  102. 
Macksburg  sand,  96. 
MacLaren,  M.,  695,  745. 
McLean,  T.  A.,  749. 


844 


INDEX 


McMurray,  Alberta,  225. 
Mace,  C.  N.,  406. 
Mace,  Ido.,  660. 
Madagascar,  graphite,  351. 
Madden,  G.  C.,  618. 
Madoc,  Ont.,  332. 
Madoc  Township,  Ont.,  410. 
Madrid,  N.  Mex.,  9. 
Magdalena,  N.  Mex.,  626. 
Magdalen  Islands,  Can.,  253. 
Magmatic  emanations,  444. 
Magmatic  ore  bodies,  form,  432. 

metals  in,  432. 
Magmatic  copper,  572. 

iron,  505,  517. 
segregations,  430. 
Magmatic  water,  440. 

in  ore  formation,  441. 
Alagnalium,  756. 
Magnesite,  analyses,  359. 
California,  356. 
dolomite  type,  356. 
origin,  356. 
production,  360. 
properties,  355. 
references,  362. 
serpentine  type,  356. 
uses,  360. 
Magnetite,  Adirondack  region,  505. 

non-titaniferous  deposits,  505. 
origin  of,  511. 
sand,  Quebec,  524. 
sandstone,  523. 
titaniferous,  520,  524. 

concentration  tests, 

522. 

United  States,  504. 
Magnus,  H.,  296. 
Mahoning  sand,  96. 
Mahren,  Austria,  351. 

Maine,  copper,  573;   feldspar,  323;   granite, 
147;    graphite,  349;    molybdenum,  793; 
slate,  162;   tourmaline,  386. 
Malachite,  568. 
Malay  Peninsula,  tin,  816. 
Malcolm,  W.,  135,  749. 
Maicolmson,  J.  W.,  673. 
Maiden,  W.  Va.,  230. 
Mallock,  G.  S.,  68. 
Maltha,  117,  122. 
Mammoth  seam,  Pa.,  23. 
Manganese,  analyses  of,  764. 

classes  of  ore,  759. 
effect  on  gold  enrichment,  677. 
foreign  deposits,  768. 
iron  ores,  767. 
ore  minerals,  758. 
origin  of  ores,  760. 
prices,  769. 
production,  768. 
reference,  771. 
silver  ores,  767. 
United  States,  760. 
uses,  768. 
value  of  ores,  489. 
Manganite,  759. 
Manistee,  Mich.,  220. 
Manitoba,  gypsum,  255;  limestone,  164. 
Manjak,  121,  126. 
Mankato,  Minn.,  190. 


Mansfeld,  Ger.,  609. 
Mansfield,  G.  W.,  276. 
Mapimi,  Mex.,  784. 
Marble,  as  building  stone,  149. 
Canada,  164. 
characteristics  of,  149. 
definition,  150. 
foreign,  164. 
United  States,  152. 
uses,  154. 

Marbut,  C.  F.,  185. 
Marienberg,  Sax.,  826. 
Marion,  Ky.,  333. 
Marksville,  Va.,  521. 
Marlow,  Okla.,  253. 
Marquette,  Mich.,  528. 
Marquette  range,  528. 
Marsters,  V.  F.,  308,  309. 
Martin,  G.  C.,  66,  133,  208,  283,  746. 
Maryland,  building  stone,  149;    clay,  17£ 
180;    chromite,  791;    coal,  32;    diatoma 
ceous   earth,    320;     feldspar,    323;     glas 
sand,  342;    granite,   147;  hydraulic  lim< 
189;    magnesite,  356;    marble,  153;    na1 
ural  cement  rock,  196;    serpentine,  15€ 
siderite,  559;   slate,  162. 
Marysvale,  Utah,  242. 
Mason,  W.  Va.,  229,  239. 
Massachusetts,  emery,    294;     granite,    147 
marble,  153;   peat,  8;   pyrite,  403;   sand 
stone,  158. 
Massillon,  O.,  341. 
Matanuska,  Alas.,  48. 
Matehuala,  Mex.,  592. 
Mathews,  E.  B.,  168,  208,  327,  793. 
Matson,  G.  C.,  185,  283,  421. 
Matthew,  W.  D.,  282. 
Maxton  sand,  96. 
Mayari,  Cuba,  558. 
Maynard,  G.  W.,  793. 
Maynard,  T.  P.,  208. 
Mead,  W.  J.,  558,  754,  758. 
Meadow  Lake,  Calif.,  447,  593,  692. 
Meadow  Valley,  Calif.,  766. 
Means,  A.  H.,  746. 
Medicine  Hat,  Alberta,  50,  81,  115. 
Medicine  Lodge,  Kas.,  252. 
Mediterranean,  Usiglio's  experiments,  212. 
Meerschaum,  362. 

analyses,  363. 
references  on,  364. 
Meggen,  Ger.,  316,  403. 
Meigs  coal,  32. 
Melaconite,  568. 
Melrose,  Mont.,  275,  276. 
Mendeljeff,  D.,  79. 
Mendenhall,  W.  C.,  421,  500. 
Menefee  gas  sand,  97. 
Mercer  coal,  37. 
Mercur,  Utah,  700. 
Mercury,  extraction,  776. 

foreign  deposits,  775. 
mode  of  occurrence,  772. 
ore  minerals,  771. 
origin,  772. 
production,  777. 
references  on,  778. 
United  States,  772. 
uses,  776. 
Merrill,  F.  J.  H.,  228,  230,  259. 


INDEX 


845 


Merrill,  G.  P.,  167,  168,  169,  184,  237,  297,    | 

306,  309,  337,  340,  745. 
Merwin,  H.  E.,  618. 
Merz,  A.  R.,  243. 
Mesabi  range,  532. 
Mesler,  R.  D.,  414. 
Metacyst,  464. 
Metallogenetic  epochs,  492. 
Metallographic  study  of  ores,  496. 
Metals,  deposited  from  springs,  442. 

in  rocks,  Lindgren's  estimate,  436. 
in  rocks,  Vogt's  estimate,  435. 
occurrence  in  rocks,  434. 
Metasome,  464. 
Metasomatism,  in  ores,  462. 
Mexico,  Ky.,  315. 

Mexico,  antimony,  781;    coal,  52;    copper, 
592;     gold-silver,    686,    730;     lead-silver, 
673;     mercury,    776;     onyx,    154;     opal, 
384;   petroleum,  111;   tin,  813,  816;   tuff, 
164;   sulphur,  393. 
Meymac,  France,  787. 
Mezger,  A.,  748. 
Miami,  Ariz.,  600. 
Miargyrite,  676. 
Mica,  books,  364. 

Canada,  368. 
foreign  deposits,  368. 
mining,  368. 
occurrence,  364. 
production,  369. 
properties,  364. 
references,  370. 
structure,  365. 
United  States,  365. 
uses,  368. 
Micanite,  369. 
Micarta,  369. 

Michigan,  bromine,  229;    calcium  chloride, 
230;   cement,  202;   coal,  37;   copper,  606; 
graphite,  349;   grindstones,  286;   gypsum, 
250;  hematite,  528;  salt,  220;   sandstone, 
158;   whiting,  376. 
Michipicoten  district,  Ont.,  534. 
Mickle,  G.  R.,  136. 
Microcline,  321. 
Middle  Rlttanning  coal,  32. 
Midway,  Calif.,  91. 
Utah,  118. 
Miles,  Mont.,  8. 

Miller,  A.  M.,  318,  353,  377,  656. 
Miller,  W.  G.,  296,  308,  493,  498,  567,  749, 

778,801,805,819. 
Millerite,  795. 
Milwaukee,  Wis.,  190,  196. 
Minas  Geraes,  Brazil,  548,  695,  768. 
Mine  Hill,  N.  J.,  627. 
Minera,  Tex.,  43. 
Mineral  charcoal,  14. 
Mineral  Creek,  Ariz.,  601. 

Wash.,  783. 
Mineralizers,  446. 
Mineral  paint,  analyses,  371. 
hematite,  371. 
ochre,  371. 
production,  376. 
references,  377. 
shale,  375. 
siderite,  374. 
slate,  375. 


Mineral  Point,  Mo.,  312. 

Mineral  water,  422. 

Mineral  wax,  118. 

Minette,  556,  558. 

Mineville,  N.  Y.,  260,  508,  512. 

Mine  waters,  442,  443. 

Minnesota,  artesian  water,  418;  building 
stone,  149;  feldspar,  323;  granite,  147; 
limonite,  556;  hematite,  532;  slate,  162. 

Mirabilite,  231. 

Mirage,  N.  Mex.,  333. 

Miser,  H.  D.,390. 

Missanagra,  Peru,  826. 

Missionary  Ridge,  Tenn.,  753. 

Mississippi,  clay,  180. 

Missouri,  barite,  310;  cadmium,  788;  clay, 
179,  180,  181;  coal,  38;  glass  sand,  342; 
granite,  147;  marble,  153;  lead,  646; 
nickel-cobalt,  795;  tripoli,  412;  zinc,  640. 

Mitchell  sand,  96. 

Moa,  Cuba,  558. 

Moffat,  E.  S.,  65,  745. 

Moffit,  F.  H.,  618. 

Molding  sand.     See  Foundry  Sand. 

Molybdenite,  793. 

Molybdenum,  occurrence,  etc.,  793. 

Monazite,  analyses,  378. 
Brazil,  378. 
occurrence,  377. 
production,  379. 
properties,  377. 
references,  379. 
United  States,  378. 
uses,  379. 

Montana,  coal,  44;  copper,  573,  593;  gold- 
silver,  686;  granite,  148;  graphite,  349; 
gypsum,  252;  lead,  646;  lead-silver,  671; 
limonite,  556;  magnetite,  523;  phos- 
phate, 275;  sapphire,  385;  silver-lead, 
658;  volcanic  ash,  290. 

Monte  Amiata,  Tuscany,  775. 

Monte  Cristo,  Wash.,  470,  698. 

Montello,  Wis.,  147. 

Monterey,  Calif.,  319. 

Monterey  County,  Calif.,  46. 

Montpelier,  Ido.,  275. 

Montroydite,  771. 

Moore,  E.  S.,  406,  567,  659. 

Moore,  P.  N.,  66. 

Moore,  R.  B.,  827. 

Moosehead,  Pa.,  373,  374. 

Moose  Mountain,  Ont.,  517,  547. 

Morenci,  Ariz.,  451,  577. 

Moresnet,  Belgium,  439,  650. 

Morgantown  sand,  96. 

Morro  Velho  mine,  695. 

Moses,  A.  J.,  778. 

Mother  of  coal,  14. 

Mother  Lode,  Calif.,  695. 

Moundsville  sand,  96. 

Mountain  sand,  96. 

Mount  Bischoff,  Tasmania,  816. 

Mount  Crawford,  S.  Aus.,  821. 

Mount  Dun,  N.  Z.,  792. 

Mount  Holly  Springs,  Pa.,  414. 

Mount  Lyell,  Tas.,  614. 

Mount  Margaret,  W.  Aus.,  695.  ; 

Mount  Morgan,  Queensland,  706. 

Mt.  Pisgah  sand,  96. 

Mount  Pleasant,  Tenn.,  267,  277. 


846 


INDEX 


Moyie,  B.  C.,  659. 

Mull,  peat,  63. 

Mullan,  Ida.,  660. 

Miiller,  N.,  803. 

Muncy,  Pa.,  374. 

Munn,  M.  J.,  84,  89,  133,  134,  135. 

Murchison,  W.  Aus.,  695. 

Murdoch,  J.,  485,  497,  499,  618. 

Murfreesboro,  Ark.,  381. 

Murphy  sand,  96. 

Murray,  Ida.,  C60. 

Muscovite,  364. 

Mysore,  India,  695. 


X 


Nagyag,  Trans.,  729. 
Nagybanya,  Hungary,  729. 
Naples  yellow,  782. 
Nason,  F.  L.,  208,  297. 
National  district,  Nev.,  729. 
Native  arsenic,  783. 
Native  copper  deposits,  603. 
Natural  brines,  211. 
Natural  gas,  accumulation,  89. 
analyses  of,  78. 
•Appalachian  field,  114. 
Canada,  115. 
classification  of  sands,  87. 
compounds  in,  73. 
mode  of  occurrence,  83. 
origin  of,  79. 
pressure  decrease,  86. 
production,  127. 
properties  of,  73. 
references  on,  135. 
United  States,  113. 
uses,  116. 
well  pressure,  85. 
yield  of  well,  91. 
Natural  rock  cements,  distribution,  194. 

properties,  190. 
Nebraska,  volcanic  ash,  290. 
Neihart,  Mont.,  671,  767. 
Neill,  J.  M.,  805. 
Nelson  County,  Va.,  822. 
Nelson,  W.  A.,  67,  186,  771. 
Nelsonite,  260,  820. 

Nevada,     antimony,     780;    bismuth,    786; 
borax,  233;   copper,  585;   gold-silver,  686; 
708,  714;   gypsum,  252;    manganese,  767; 
opal,  384;    platinum,   806;    potash,  242; 
salt,  224;   silver-lead,  671;   tungsten,  823. 
Nevada  City,  Calif.,  696. 
Nevada  County,  Calif.,  696. 
Nevius,  J.  N.,  296. 
New  Almaden,  Calif.,  773. 
Newberry,  J.  S.,  17,  81,  133. 
New  Brunswick,  albertite,  118;    antimony, 
780;     building    stone,     162;      clay,     182; 
gypsum,  255;   iron,  516;   natural  gas,  115; 
oil    shale,    125;     petroleum,    111;     sand- 
stone, 164. 
New  Caledonia,  chromite,  792. 

nickel,  803. 
Newfoundland,  grinding  pebbles,  295;  iron, 

546. 

New  Guinea,  copper,  605. 
New  Hampshire,  garnet,  291;    granite,  168; 
scythestones,  287. 


New  Idria,  Calif.,  773. 

New  Jersey,  cement,  202;  clay,  180;  copper, 
605;  diabase,  148;  foundry  sand,  337; 
glass  sand,  342;  green  sand,  279;  iron, 
511;  shale  paint,  375;  slate,  162;  talc, 
409;  zinc,  626. 

Newland,  D.  H.,  136,  168,  259,  282,  297, 
337,  343,  353,  377,  406,  512,  565,  566,  656, 
786. 

New  Mexico,  bauxite,  755;  cadmium,  788; 
coal,  42;  copper,  586,  601;  fluorspar,  329; 
garnet,  383;  graphite,  349;  gypsum,  252; 
iron,  516;  lead-silver,  671;  lead-zinc,  626; 
meerschaum,  363;  salt,  224;  turquoise, 
386;  uranium,  826;  vanadium,  826. 

New  River  district,  Va.,  762. 

Newsom,  J.  F.,  278,  283. 

New  South  Wales,  bismuth,  788;  coal,  52; 
cobalt,  803;  lead-silver,  659;  tungsten, 
824. 

New  York,  cement,  202;  cement  rock,  194; 
diabase,  148;  diatomaceous  earth,  320; 
emery,  294;  feldspar,  322;  foundry  sand, 
337;  garnet,  291;  glass  sand,  342;  graph- 
ite, 346;  gypsum,  249;  hydraulic  lime, 
189;  iron,  505,  521,  543;  lime,  193;  mill- 
stones, 284;  mineral  paint,  371;  natural 
cement  rock,  196;  natural  gas,  114;  pe- 
troleum 95;  pyrite,  403;  salt,  220; 
sandstone,  158;  slate,  162;  talc,  408; 
vein  quartz,  391;  whetstones,  287;  zinc, 
656. 

New  Zealand,  chromite,  792;    gold  placers, 
678;     gold-silver,    729;     magnetite   sand, 
•  523;   platinum,  805. 

Niccolite,  795. 

Nicholls,  W.  J.,  65. 

Nickel  bloom,  795. 

Nickel,  Canada,  807. 

ore  minerals,  794. 

other  foreign  deposits,  803. 

production,  804. 

references  on,  805. 

United  States,  795. 

uses,  803. 

value  of  ores,  489. 

Nickel  Plate  Mine,  Brit.  Col.,  686. 

Nictaux,  N.  S.,  547. 

Nictaux-Torbrook  basin,  N.  S.,  548. 

Niles,  Mich.,  336. 

Niles,  O.,  341. 

Nineveh  sand,  97. 

Nissen,  A.E.,  658. 

Nitze,  H.  B.  C.,  379,  565,  747. 

Nizhni-Tagilsk,  Russia,  807. 

North  Carolina,  barite,  315;  clay,  179;  coal, 
35;  chromite,  791;  copper,  611;  corun- 
dum, 293;  emerald,  383;  garnet,  29; 
gold,  691;  granite,  147;  manganese,  766; 
mica,  365;  monazite,  378;  phosphate,  278; 
ruby,  385;  sandstone,  158;  sapphire,  385; 
talc,  408;  tin,  814. 

North  Castle,  N.  Y.,  323. 

North  Dakota,  cement,  202;  coal,  44. 

Norton,  W.  H.,  421. 

Norway,  copper,  573,  605;  feldspar,  324; 
magnetite,  524;  titanium,  821. 

Norwood,  C.  J.,  66. 

Novaculite,  287. 

Nova  Scotia,  antimony,  780;    barite,  316; 


INDEX 


847 


Nova  Scotia,  building  stone,  102;  clay,  182; 
coal,  47;  copper,  605;  gold,  705;  gyp- 
sum, 254;  iron,  548;  molybdenum,  794; 
tungsten,  824. 

Nystrom,  E.,  68. 

O 

Oberfell,  G.  G.,  78. 
Ocher,  analyses,  374. 
Canada,  374. 
occurrence,  371. 
origin,  372. 
properties  of,  371. 
United  States,  372. 
Ochsenius,  C.,  215,  228. 
Ogdensburg,  N.  J.,  627. 
Ogilvie,  I.,  353. 
O'Harra,  C.  C.,  259,  689,  749. 
Ohio,  calcium  chloride,  230;    cement,   182; 
clay,   179,   180;    coal,   32;    foundry  sand, 
337;  gas,  114,  115;  glass  sand,    343;   nat- 
ural cement  rock,    197;   grindstones,   286; 
gypsum,  252;  petroleum,  98;  pyrite,  403; 
salt,    220;    sandstone,    158;    siderite,  559. 
Oil.      See  Petroleum. 
Oilstones,  287. 
Ojo  Caliente,  N.  Mex.,  443. 
Oklahoma,   asphalt,    118,    120;.  bituminous 
rock,    125;     granite,    147;     gypsum,   252; 
natural  gas,  115;    petroleum,  102;    salt, 
224. 

Olcott,  E.  E.,  673. 
Old  Dominion  mine,  600. 
Oliphant,  F.  H.,  101. 
Olive  Hill,  Ky.,  751. 
Olivine  Mountain,  B.  C.,  382. 
Olsen,  Tex.,  8. 
Onondaga,  N.  Y.,  253. 
Onofrite,  771. 

Ontario,  apatite,  261;    asphalt,  118;    build- 
ing stone,  162;   cement,  202;   cobalt,  800; 
corundum,  294;    feldspar,  324;    fluorspar, 
332;   glass  sand,  343;   gold,  694;   gypsum, 
255;  hematite,  534;  limestone,  164;  mag- 
netite,  517,   magnetite,  titaniferous,   524; 
marble, '164;  mica,  368;  nickel,  796,    807; 
ocher,  374;  pebbles,  grinding,  295;  petrol- 
eum,    111;   platinum,    807;    pyrite,   403; 
salt,  225;  sandstone,  164;  silver,  800;  talc, 
410;    titanium,  820. 
Onyx  marbles,  153. 
Ooltewah,  Tenn.,  371. 
Opal,  properties,  384. 

sources,  384. 
Orange  stone,  287. 
Orcutt,  Calif.,  319. 
Ordonez,  E.,  Ill,  471,  730. 
Ore  channels,  473. 
Ore  deposits,  bedded,  472. 

cavities,  origin  of,  455. 
chimneys,  472. 
classification  of,  489. 
contact  metamorphic,  448. 
contemporaneous,  430. 
denned,  429. 

disposition  in  cavities,  456. 
epigenetic,  430,  434. 
fahlband,  472. 
forms  of,  466. 
gangue  defined,  422. 


Ore  deposits,  gossan,  476. 

hydrothermal  alteration,  486. 
impregnations,  473. 
interstratified       sedimentary, 

433. 

magmatic  segregations,  430. 
minerals    of    different    zones, 

458. 

mode  of  concentration,  444. 
ore  defined,  429. 
ore  minerals  denned,  429. 
origin,  430. 
oxidized  zone,  479. 
pegmatites,  446. 
placers,  433. 
references  on,  497. 
secondary  changes,  475. 
secondary     sulphide     enrich- 
ment, 481. 
sedimentary,  432. 
shallow  depth  origin,  454. 
shoots,  474. 
stocks,  472. 
stockwork,  472. 
subsequent,  430. 
surface  deposition,  455. 
syngenetic,  430. 
veins,  466. 
weathering,  476. 

Oregon,  borax,  233;    coal,  45;    copper,  593, 
605;     gold,   698;     granite,    148;   limonite, 
556;     mercury,   773;     nickel,   795;     plat- 
inum, 806;   volcanic  ash,  299. 
Ore  Knob,  N.  C.,  611. 
Ore  minerals,  429. 
Ores,  429. 

metallography  of,  496. 
precipitation  from  solution,  456. 
Ore  shoots,  474. 
Ores,  value  of,  486. 
Ore,  tenor  of,  Bingham,  Utah,  585. 
Bisbee,  Ariz.,  577. 
Broken  Hill,  N.  S.  W.,  659. 
Butte,  Mont.,  599 
Coeur  d'  Alene,  Ido.,  663. 
copper,  Michigan,  609. 
Deadwood,  B.  C.,  591. 
Ducktown,  Tenn.,  610. 
Ely,  Nev.,  586. 
Kootenay,  B.  C.,  672. 
Mother  Lode,  Calif.,  696. 
Park  City,  Utah,  665. 
siliceous  gold  ores,  S.  D.,  698. 
Sudbury,  Ont.,  800. 
Sussex  Co.,  N.  J.,  628. 
Wisconsin,  650. 
Organ,  N.  Mex.,  453. 
Oriskany  limonite,  555. 
Orlando,  Fla.,  8. 
Oroville,  Calif.,  806. 
Orpiment,  783. 
Orthoclase,  321. 
Orton,  E.,  67,  85,  133,  134,  135,  136,  168, 

185,  259,  565,  566. 
Orton,  Jr.,  E.,  186,  209. 
Osgood,  S.  W.,  656. 
Osmiridium,  805. 
Osmium,  occurrence,  808. 
Ottawa,  111.,  341. 
Otter  sand,  96. 


848 


INDEX 


Ouray,  Colo.,  470,  728. 
Outcrops,  coal,  22. 
ore,  476. 

Overbeck,  R.  M.,  619. 
Ovitz,  F.  K.,  65. 
Owens.  Lake,  Calif.,  241 
Oxidized  ore  zone,  reactions  in,  479. 
Ozark  Region,  lead  zinc  deposits,  639. 
Ozokerite,  118,  126. 


Pachuca,  Mex.,  730. 

Pack,  F.  J.,  674. 

Pagliucci,  F.  D.,  778. 

Paige,  S.,  390,  565,  619,  748. 

Pala,  Calif.,  354. 

Palladium,  Nev.,  806. 

Palladium,  occurrence  and  use,  808. 

Palmer,  C.,  499,  745. 

Pandermite,  236. 

Panuco,  Mex.,  111. 

Paola,  Kas.,  102. 

Pappoose  sand,  96. 

Paraffin,  native,  118. 

Paralic  coals,  13. 

Pardee,  J.  T.,  283,  297,  321,  748. 

Parian  marble,  164. 

Paris,  Ark.,  9. 

France,  255. 

Park,  J.,  497. 

Park  City,  Utah,  664. 

Parker,  E.  W.,  54. 

Parker  coal,  32. 

Parks,  H.  M.,  168. 

Parks,  W.  A.,  169. 

Parmelee,  C.  W.,  68,  337. 

Parr,  S.  W.,  19,  25,  65,  66,  414. 

Parral,  Mex.,  730. 

Parsons,  A.  L.,  283,  749. 

Parsons,  C.  L.,  68,  338,  340,  827. 

Partinium,  756. 

Passau,  Bav.,  344,  350. 

Patagonia,  Ariz.,  242. 

Patten,  H.  E.,  262. 

Patton,  H.  B.,  390,  746. 

Patronite,  825. 

Peace  River,  Fla.,  263. 

Pearce,  R.,  827. 

Pearcite,  676. 

Pearl  Creek,  N.  Y.,  225. 

Peat,  analyses  of,  8. 

analyses  of  layers  in,  1. 
origin,  61. 
production,  64. 
uses,  63. 

Pebble  phosphate,  265. 

Pebbles,  grinding,  295. 

Peck,  F.  B.,  209,  412. 

Peckham,  S.  F.,  133,  136,  137. 

Pegmatite  dikes,  446. 

Pennsylvania,  clay,  179,  181;  chromite, 
791;  coal,  29,  31;  building  stone,  148, 
156,  158,  162;  feldspar,  323;  glass  sand, 
342;  graphite,  348;  lead-zinc,  639; 
limonite,  555;  magnesite,  356;  magne- 
tite, 512;  manganese,  766;  millstones, 
284;  natural  cement  rock,  196;  nat- 
ural gas,  114;  nickel,  795;  ocher,  373; 
petroleum,  95;  phosphate,  278;  Port- 
land cement,  198;  siderite,  559;  sider- 


ite     paint,    374;    shale    paint,   375;  vein 
quartz,  391. 

Penokee-Gogebic  range,  530. 
Penrose,  R.  A.  F.,  279,  283,  390,  499,  501, 

564,  566,  677,  745,  764,  771. 
Peppel,  S.,  168,  209. 
Pepperberg,  L.  J.,  656. 
Peridot,  properties,  384. 
Perkins,  G.  H.,  168. 
Permanent  swelling,  in  stone,  143. 
Perrett,  L.,  809. 
Perrine,  I.,  134,  136. 
Persian  Gulf,  247. 
Peru,  vanadium,  827. 
Petersburg,  Va.,  336. 
Petersen,  W.,  277. 
Petit  Anse,  La.,  223,  225. 
Petroleum,  accumulation,  89. 

Alaska,  109. 

analyses,  elementary,  71. 

analyses  of,  74. 

anticlinal  theory,  87. 

Appalachian  field,  92. 

asphaltic  base,  71. 

California,  102. 

Canada,  110. 

classification  of  sands,  87. 

Colorado,  108. 

composition,  70. 

distillates,. 73. 

foreign  deposits,  113. 

Illinois  field,  99. 

life  of  well,  91. 

Mexico,  111. 

mid-continental  field,  102. 

mode  of  occurrence,  83. 

Ohio-Indiana  Field,  98. 

optical  properties,  71. 

origin  of,  79. 

paraffin  base,  70. 

pool,  83. 

production,  127. 

properties  of,  70. 

references  on,  133. 

rock  pressure,  85. 

sand,  83. 

sands,  yield  of,  91. 

shales,  125. 

specific  gravity,  72. 

sulphur  in,  71. 

summary  of  fields,  110. 

Texas,  106. 

United  States,  91. 

distribution,  91. 

uses,  116. 

viscosity,  72. 

well  pressure,  85. 

wells,  life  of,  91. 

Wyoming,  109. 
Phalen,  W.  C.,  185,  228,  243,  318,  321,  400, 

406,  566. 

Philippines,  coal,  52. 
Philipsburg,  Mont.,  686. 
Phillips.  F.  C.,  81,  497. 
Phillips,  W.  B.,  67,  68,  135,  137,  283,   406, 

620,  745,  748,  758,  778. 
Phlogopite,  364. 
Phoenix,  B.  C.,  590. 
Phosphate,  analyses  of,  272,  276. 

blanket  deposits,  268. 


INDEX 


849 


Phosphate,  classification,  261. 
collar  deposits,  267. 
cutters,  2(58. 
foreign  deposits,  280. 
hard  rock,  263. 
impurities,  262. 
land  pebble,  266. 
minerals  in,  261. 
origin  of,  262. 
rim  deposits,  267. 
United  States,  263. 
Phosphorite,  261. 
Pi?tou,  N.  S.,  coal  basin,  47. 
Piers,  H.,  819. 
Pignerolles,  Italy,  409. 
Pike  sand,  96. 
Pike  Station,  N.  H.,  287. 
Pilbarra,  W.  Aus.,  695. 
Pipe  clay,  176. 
Pirsson,  L.  V.,  390,  747,  786. 
Pishel,  M.,  65. 
Pitchblende,  825. 
Pitch  length,  474. 
Pitkaranta,  Finland,  452,  811. 
Pittman,  E.  F.,  788,  803. 
Pittsburg,  Pa.,  226,  229. 
Pittsburg  coal,  24,  32. 
Pittsville,  Va.,  554,  557. 
Placer  deposits,  433. 
Placer  gold,  Alaska,  734. 
Placers,  gold,  amount   gold  obtained  from, 

679. 

California,  731. 
dredging,  678. 
dry,  730. 
eluvial,  730. 
eolian,  730. 
gold,  678,  730. 
marine,  731. 
minerals  in  gold,  731. 
Russia,  737. 
size  of  gold  in,  731. 
stream,  730. 
Victoria,  737. 
Yukon  Ty.,  736. 
Placers,  platinum,  805. 

tin,  814. 
Plagioclase,  322. 
Plasterco,  Va.,  222. 
Plaster  of  paris,  256. 
Plasticity  of  clay,  172. 
Platinum,  Canada,  807. 

composition,  806. 
foreign  deposits,  807. 
occurrence,  805. 
production,  807. 
references  on,  808. 
United  States,  806. 
uses,  807. 
value  of  ores,  489. 
Plumas  County,  Calif.,  573. 
Plumbojarosite,  806. 
Pneumatolysis,  446. 
Pocahontas  coal  field,  34. 
Pogue,  J.  E.,  390,  619. 
Pohlman,  J.,  208. 
Point  Sal,  Calif.,  319. 
Polargyrite,  676. 
Polybasite,  676. 
Polyhalite,  214. 


Pomeroy,  O.,  220,  222,  229,  230. 
Pomeroy  coal,  32. 
Poole,  H.  S.,  68,  318. 
Pope  County,  111.,  328. 
Pope,  F.  J.,  499. 
Pope's  Creek,  Md.,  319. 
Popocatepetl,  Mex.,  393. 
Porcupine,  Ont.,  694. 
Porter,  H.  C.,  65. 
Porter,  J.  B.,  68. 
Porter,  J.  T.,  340. 
Porterville,  Calif.,  356,  359. 
Port  Graham,  Alas.,  46. 
Portland  cement,  analyses,  193. 
formula,  192. 
properties  of,  191. 
United  States,  197. 
Portland  stone,  164. 
Portugal,  tungsten,  824. 
Posepny,  F.,  438,  441,  489,  497,  499. 
Posnjak,  E.,  618. 
Potash,  alunite,  242. 

brines  and  bitterns,  239. 

igneous  rocks,  242. 

kelp,  243. 

monzonite,  243. 

Portland  cement,  243. 

saline  lake  beds,  239. 
Pot  clay,  176. 
Potonie.,  H.,  12,  65. 
Pottsville  coal,  32. 
Powder  river  coal  basin,  Wyo.,  44. 
Pozzuolan  cement,  188. 
Pozzuolano,  Italy,  188. 
Prairie  City,  Ore.,  796. 
Prather,  J.  K.,  203. 
Pratt,  J.  H.,  296,   306,  309,  318,  334,  370, 

379,  390,  393,  412,  793. 
Precious  stones,  production,  388. 
properties,  380. 
references,  390. 
Premier  mine,  S.  Afr.,  382. 
Prescott,  B.,  497,  565. 
Pretoria,  Transvaal,  382. 
Primary  minerals,  in  ores,  481. 
Prime,  F.,  209,  565. 
Prince  William  County,  Va.,  401. 
Prince  William,  N.  B.,  780. 
Prince  William  Sound,  Alas.,  613. 
Prindle,  L.  M.,  745. 
Proctor,  Vt.,  153. 
Producer  gas,  analysis  of,  79. 
Propylitization,  486. 
Prosser,  C.  S.,  185. 
Proustite,  676. 
Providence,  R.  I.,  348. 
Przibram,  Bohemia,  469,  672. 
Psilomelane,  758. 
Puente  Hills,  Calif.,  102, 
Pulpstones,  287. 
Pumice,  288,  290. 
Pumpelly,  R.,  466,  608. 
Punjab,  ludia,  225. 
Purdue,  A.  H.,  167,  278,  283,  390. 
Purdy,  R.  C.,  185. 
Purington,  C.  W.,  737,  746,  809. 
Put-in-Bay,  L.  Erie,  393. 
Pyrargyrite,  676. 
Pyrite,  analyses  of,  402,  403. 
Canada,  403. 


850 


INDEX 


Pyrite,  foreign  deposits,  404. 

mode  of  occurrence,  401. 

occurrence,  400. 

origin,  402. 

production,  404. 

properties,  400. 

references  on,  406. 

requirements  of,  401. 

United  States,  401. 

uses,  404. 
Pyrolusite,  758. 
Pyromorphite,  622. 
Pyrope,  383. 
Pyrophyllite,  411. 

Pyrrhotite,  effect  on  gold  and  silver  migra- 
tion, 677. 
(nickel),  795. 


Quarry  water,  142. 

Quartz,  flint,  391. 

quartzite,  391. 
references  on,  392. 
uses,  391. 
vein,  391. 

Quebec,  apatite,  261 ;  asbestos,  302;  build- 
ing stone,  162;  cement,  202;  chromite, 
791;  clay,  181;  copper,  613;  gold,  694; 
graphite,  349;  limonite,  556;  marble, 
164;  magnetite,  titaniferous,  524;  mica, 
368;  molybdenum,  794;  ocher,  374;  py- 
rite,  404;  sandstone,  164;  slate,  164; 
soapstone,  410;  titanium,  820;  tung- 
sten, 824. 

Quebec  City,  Can.,  164. 

Queensland,  bismuth,  787;  gold,  706;  tung- 
sten, 824. 

Quercy,  France,  280. 

Queretaro,  Mex.,  384. 

Quicksilver,  771. 

Quisquerite,  827. 

R 

Ragland  oil  sand,  97. 

Raible,  Austria,  651. 

Railroad  Valley,  Nev.,  242. 

Rainy  Lake  district,  Ont,,  694. 

Rambler  mine,  Wyo.,  806. 

Rammelsberg,  Ger.,  603. 

Ramona,  Calif.,  386. 

Rankin,  G.  S.,  192. 

Ransome,  F.  L.,  474,  481,  485,  486,  498, 
500,  618,  619,  656,  660,  673,  674, 
746,  747,  778,  825,  827. 

Rapikivi  granite,  146. 

Raton  coal  field,  Colo.,  42. 

Raton,  N.  M.,  349. 

Ravicz,  L.  G.,  500. 

Ray,  Ariz.,  601. 

Ray,  J.  C.,  619. 

Raymond,  R.  W.,  566. 

Reading,  Pa.,  373. 

Read,  T.  T.,  498. 

Real  del  Monte,  Mex.,  730. 

Realgar,  783. 

Red  Beds,  copper  in,  609. 

Redjang  Lebong,  Sumatra,  729. 

Redlich,  K.,  362. 

Red  Lodge,  Mont.,  44. 


Red  Mountain,  Ala.,  543. 
Redstone  coal,  32. 
Redwood,  B.,  82,  133. 
Regulus,  defined,  782. 
Reid,  H.  F.,  498. 
Reid,  J.  A.,  618. 
Renwick,  W.  G.,  167. 
Replacement,  criteria  of,  465. 

in  ores,  462. 

Republic  district,  Washington,  729,  809. 
Retsof,  N.  Y.,  225. 
Rewold,  Va.,  784. 

Rhode  Island,  granite,    147,    graphite,    348. 
Rhodesia,  chromite,  792. 
Rhodochrosite,  759. 
Rice,  W.  N.,  392. 
Rich,  J.  L.,  565. 
Richards,  R.  W.,  276,  283,  400. 
Richardson,  C.,  122,  136,  422. 
Richardson,  C.  H.,  309. 
Richardson,  G.  B.,  135,  228,  400,   783,   786, 

819. 

Richmond,  Va.,  5,  319.  335. 
Rickard,  F.   827. 
Rickard,  T.  A.,  500,  501,  619,  673,  706,  745, 


Rico,  Colo.,  670. 

Riddles,  Ore.,  796. 

Ridgway,  Va.,  367. 

Ries,  H.,  68,  167,  170,  171,  184,  185,  186, 

208,  321,  337,  340,  758. 
Rift,  144. 

Riggs  Station,  Calif.,  409. 
Rio  Tinto,  Spain,  403,  614. 
Ritchie  County,  W.  Va.,  118 
Robellaz,  F.,  745. 
Robinson,  H.  H.,  137. 
Rockbridge  Co.,  Va.,  784. 
Rock  Glen,  N.  Y.,  239. 
Rock  phosphates.     See  Phosphates. 
Rock  Run,  Ala.,  751,  765. 
Rock  salt,  212. 
Rockton,  111.,  335. 

Rogers,  A.  F.,  259,  481,  498,  501,  619. 
Rogers,  G.  S.,  283. 
Rogers.  H.  D.,  4,  793. 
Rolfe,  C.  W.,  185. 
Roman  cement,  190. 
Roros,  Norway,  573. 
Roscoelite,  825. 
Roseland,  Va.,  821. 
Rosen,  J.  A.,  337. 
Rosendale  cement,  190. 
Rosendale,  NvY.,  191,  196. 
Rosita,  Colo.,  329,  333. 
Ross,  C.  S.,  566. 
Ross,  W.  H.,  243. 
Rossland,  B.  C.,  593. 
Routivare,  Swe.,  524. 
Rowe,  J.  P.,  66,  168,  297,  353,  825. 
Rubellite,  386. 
Ruby,  384. 

Ruddy,  C.  A.,  68,  422. 
Riidersdorf,  Ger.,  191. 
Ruhm,  H.  D.,  267. 
Rumbold,  W.  R.,  816. 
Rundall,  W.  H.,  778. 
Runner,  J.  J.,  825. 
Runs,  Joplin  district,  642. 
Rusk,  Tex.,  557. 


INDEX 


851 


Russell,  I.  C.,  208,  545,  566. 

Russellville,  Ark.,  9. 

Russia,  asbestos,  307;  coal,  52;  copper, 
609,  614;  gold  placers,  737;  iron,  518; 
manganese,  768;  petroleum,  113;  plat- 
inum, 807;  salt,  225. 

Rutile,  occurrence,  etc.,  819. 

Rutland,  Vt.,  153. 

Rutledge,  J.  J.,  546,  566. 


Sagger  clay,  176. 

Saginaw,  Mich.,  9,  38,  226,  239. 

Saginaw  Valley,  Mich.,  220,  230. 

St.  Charles,  Mo.,  35. 

St.  Eugene  mine,  Moyie,  659. 

St.  Ignace,  Mich.,  250. 

St.  Louis,  Mo.,  35. 

St.  Nicholas,  Pa.,  9. 

St.  Urbain,  Que.,  524,  820. 

Sala,  Swe.,  659. 

Sales,  R.,  500,  596,  619. 

Salina,  Kansas,  253. 

Salines,  210. 

Salisbury,  Conn.,  557. 

Sail  Mountain,  Ga.,  298,  300. 

Salmon  River,  B.  C.,  253. 

Salt,  Canada,  225. 

desert  theory,  216. 

extraction  of,  225. 

foreign  deposits,  225. 

geologic  distribution,  218 

in  brines,  211. 

in  sea  water,  211. 

marshes,  211. 

occurrence,  211. 

origin  of,  212. 

production,  226. 

references  on,  228. 

rock,  212. 

types  of  occurrence,  210. 

United  States,  218. 

uses,  226. 
Salt  sand,  96. 
Salton  Lake,  Calif.,  224. 
Saltville,  Va.,  225,  226. 
San  Cristobal,  Colo.,  242. 
Sand,  chromite,  791. 
foundry,  334. 
glass,  340. 
gypsum,  253. 
magnetite,  523. 
monazite,  377. 
Sandberger,  F.,  434,  497. 
Sandstones,  building  stonos,  156. 
Canada,  164. 
properties,  156. 
United  States,  158. 
uses  of,  159. 
varieties,  158. 

Sandusky,  O.,  192,  252,  253. 
Sanford,  S.,  421. 
Sanford  Hill,  N.  Y.,  520. 
San  Francisco  Bay,  Calif.,  211. 
San  Francisco  district,  Utah,  668. 
San  Joaquin  Valley,  Calif.,  102. 
San  Jose,  Mex.,  592. 
San  Juan,  Chile,  448. 
San  Juan  Region,  Colo.,  722. 
San  Pedro,  N.  Mex.,  452. 


Santa  Barbara,  Calif.,  122. 

Santa  Clara  Valley,  Calif.,  102. 

Santa  Eulalia,  Mex.,  673. 

Santa  Maria,  Calif.,  102. 

Santa  Maria  field,  Calif.,  104. 

Santander,  Spain,  651. 

Santa  Rita,  N.  Mex.,  586. 

Sap,  quarry,  143. 

Sapphire,  385. 

Sardinia,  zinc,  651. 

Saskatchewan,  Can.,  clay,  181;   coal,  49. 

Saucon  Valley,  Pa.,  639. 

Savage,  T.  E.,  422,  566. 

Schaller,  W.  T.,  778,  825. 

Scheelite,  822. 

de  Schmid,  H.,  283,  334,  370. 

Schneeberg,  Sax.,  787,  803,  826. 

Schofield,  S.  J.,  674. 

Schrader,  F.  C.,    67,    134,    243,    656,    745, 

746,  747. 

Schrauf,  A.,  772,  778. 
Schreiber,  H.,  63. 
Schuchert,  C.,  13. 
Schuermann,  F.,  484. 
Schultz,  A.  R.,  231,  283,  748. 
Schuylkill  Co.,  Pa.,  9. 
Schwartz,  E.  H.  L.,  737. 
Schwarzenberg,  Ger.,  811. 
Schwatzite,  771. 
Scotland,  coal,  52;   granite,  164;    oil  shale, 

125. 

Scranton,  Pa.,  9. 
Searle,  A.  B.,  182. 
Searles  Lake,  Calif.,  241. 
Seattle,  Wash.,  45. 
Secondary  ore  minerals,  481. 
Seger,  H.,  322. 
Selenite,  244. 

Selenium,  occurrence  and  uses,  809. 
Sellards,  E.  H.,  263,  283,  340,  421. 
Selvage,  468. 
Semianthracite  coal,  analyses  of,  9. 

properties  of,  4. 
Senarmontite,  779. 
Sepiolite.     See  Meerschaum. 
Serpentine,  for  building,  154. 
Severn  River,  Md.,  342,  361. 
Sericitization,  487. 
Seward  Peninsula,  placers,  735. 
Seyssel,  France,  124. 
Shale,  for  cement,  191. 
Shaler,  M.  K.,  134,  185. 
Shaler,  N.  S.,  68,  565. 
Shannon,  C.  W.,  565. 
Sharon  coal,  32. 
Sharwood,  W.  J.,  745. 
Shaw,  E.  W.,  135. 
Shawangunk  grit,  284. 
Sheaf er,  A.  W.,  265. 
Shear  zones,  474. 
Shedd,  S.,  168,  186. 
Sheep  Creek,  Calif.,  409. 
Sheet  ground,  zinc,  642. 
Sheeted  zones,  474. 
Shepard,  E.  M.,  422. 
Shepherd,  E.  S.,  441,  498. 
Shoots,  ore,  468. 
Shungnak,  Alas.,  791. 
Siberia,  coal,  52;   graphite,  345. 
Sicily,  sulphur,  398. 


852 


INDEX 


Siderite,  as  ore,  558. 

iron  ore  mineral,  503. 
as  paint,  374. 
foreign  deposits,  559. 
United  States,  559. 
Siderite  paint,  analyses,  375. 
Siebenthal,  C.  E.,  168,  208,  297,  413,  414, 

642,  656,  789. 
Sierra  Mojada,  Mex.,  673. 
Siggins  pool,  99. 

Silesia,  cadmium,  788;  zinc,  651. 
Silification,  487. 
Silver  Bell,  Ariz.,  586. 
Silver  City,  N.  Mex.,  755. 
Silver-lead  ores,   Canada,  659,  671. 

deep   vein   zone   deposits, 

658. 

foreign  deposits,  659,  672. 
intermediate  depths,  660. 
occurrence,  658. 
references,  673. 
shallow     depth     deposits, 

673. 
United    States,    658,    660, 

673. 

Silver  ores,  fissure  veins,  types  of,  676. 
occurrence,  mode  of,  676. 
minerals,  675. 
secondary  enrichment,  481. 
uses  of,  738. 
value  of  ores,  488. 
See  gold-silver. 
Silver  Peak,  Nev.,  686. 
Silver  Plume,  Colo.,  702. 
Silverton,  Colo.,  470,  727. 
Singewald,  J.  T.,  564,  565,  813,  816,  819. 
Sinter,  tin  bearing,  814. 
Sjogren,  H.,  517,  518,  573,  659. 
Skutterudite,  795. 
Skyros  marble,  164. 
Slag  cement,  189. 
Slate,  Canada,  164. 

classification,  160. 
properties  of,  159. 
United  States,  160. 
uses,  162. 
Wales,  164. 
Slichter,  C.  S.,  416. 
Slickford  sand,  96. 
Slip  clay,  176. 

Sloane,  E.,  168,  186,  297,  370. 
Slocan  district,  B.  C.,  824. 
Slosson,  E.  F.,  135,  259. 
Smaltite,  795. 
Smith,  C.  D.,  134,  135. 
Smith,  E.  A.,  167,  184,  207,  283,  353,  421. 
Smith,  F.  C.,  748. 
Smith,  G.  O.,  66,  67,  345,  353,  422,  656,  666, 

674,  747,  748,  794. 
Smith,  H.  D.,  501. 
Smith,  J.  K.,  827. 
Smith,  P.  S.,  353,  618,  745. 
Smith,  W.  D.,  65. 

Smith,  W.  S.  T.,  334,  642,  645,  656. 
Smith  County,  Tenn.,  330. 
Smith  sand,  97. 
Smithsonite,  621. 
Smock,  J.  C.,  168,  565,  566. 
Smyth,  Jr.,  C.  H.,  406,  412,  499,  545,  566, 
644. 


Smyth,  H.  L.,  565. 

Snee  sand,  97. 

Snider,  L.  C.,  186,  228,  259,  656. 

Soapstone,  properties,  407. 

Soapstone.      See  Talc. 

Sodium  sulphate,  231. 

Soldiers  Summit,  Utah,  118. 

Solenhofen,  Bavaria,  355. 

Somermeier,  E.  E.,  65,  67. 

Somers,  R.  E.,  619. 

Sonora,  Mex.,  346,  351. 

Soper,  E.  K.,  185. 

Souris  coal  field,  Can.,  50. 

South  Africa,  gold,  737. 

South  Australia,  titanium,  821. 

South  Carolina,  clay,  179,  180;    gold,  691; 

manganese,    766;     phosphate,    266;     tin, 

814. 
South  Dakota,  artesian  water,  418;   cement, 

202;   clay,  180;    coal,  44;    gold,  690,  698; 

granite,   148;    gypsum,   252;     mica,   367; 

tin,  815;    tungsten,  824. 
South  Dover,  N.  Y.,  153. 
South  Glastonbury,  Conn.,  323. 
South  Platte  coal  field,  42. 
South  Stukely,  Que.,  164. 
Spain,  copper,  614;    garnet,  291;   iron,  548, 

559;    mercury,  775;    potash,   238;    zinc. 

651. 

Spatsum,  B.  C.,  255. 
Speechley  sand,  97. 

Spencer,  A.  C.,  345,  452,  500,  512,  565,  618, 
619,    620,    627,    628,    656,    673, 
745,  746,  786. 
Sperrylite,  805. 
Spessartite,  383. 
Spezia,  G.,  395. 
Sphagnum,  analysis  of,  1. 
Sphalerite,  621. 
Spiegeleisen,  768. 
Spilker,  A.,  81. 
Spindle  Top,  Texas,  106. 
Split  Rock,  N.  Y.,  521. 
Spodumene,  354,  385. 
Spores  in  coal,  14. 
Spring  Hill,  N.  S.,  coal,  47. 
Springs,  metalliferous  deposits,  442. 
Spring  Valley,  Wis.,  557. 
Spring  Valley,  Wyo.,  109. 
Spurr,  J.  E.,  67,  237,  400,  440,  497,  498,  499, 
592,  673,  704,  714,  745,  746,  747, 
748,  786,  809. 
Squaw  sand,  96. 
Stafford,  O.  F.,  778. 
Stannite,  811. 

Stassfurt,  Ger.,  213,  225,  229,  360. 
Steamboat  Springs,  Nev.,  434,  439,  772,  773. 
Stebinger,  E.,  565. 
Steel,  A.  A.,  318. 
Steel,  D.,  586. 
Steidtman,  E.,  501. 
Stephanite,  676. 
Sterling,  Pa.,  9. 

Sterrett,  D.  B.,  364,  370,  379,  390. 
Stevens,  B.,  501,  618. 
Stevenson,  J.  J.,  12,  16. 
Steuart,  D.  R.,  136. 
Stewart,  C.  A.,  565,  618,  620. 
Stibnite,  779. 
Stickney,  A.  W.,  614. 


INDEX 


853 


Stocks,  472. 

Stockwork,  472. 

Stoddard,  J.  C.,  377. 

Stock,  H.  H.,  67. 

Stokes   H.  N.,  745. 

Stone  Canyon,  Calif.,  46. 

Stone  Mountain,  Ga.,  147. 

Stone,  R.  W.,  67,  283. 

Stoneware  clay,  176. 

Stope  length,  474. 

Storms,  W.  H.,  499. 

Storrs,  L.  S.,  66,  67,  68. 

Stose,  G.  W.,  283,  318,  414,  620. 

Stray  sand,  96,  97. 

Stream  tin,  811. 

Streeter,  390. 

Strontianite,  392. 

Strontium,  occurrence,  392. 

uses,  393. 
Struthers,  J.,  406. 
Stutzer,  O.,  65,  282,  353,  390,  395,  448,  497, 

498,  517. 
Styria,  talc,  410. 
Subbituminous  coal,   analyses,  8. 

properties  of,  2. 
Sudbury,  Ont.,  118,  796,  807. 
Suez  Bittern  Lakes,  216. 
Suffield,  Alberta,  115. 
Sulitjelma,  Norway,  403,  573. 
Sullivan,  E.  C.,  457,  499. 
Sulphide  enrichment,  481. 

chemistry  of,  484. 

conditions  governing,  482. 

criteria  of,  481,  484. 

upward,  481. 

Sulphides,  oxidation  order,  478. 
Sulphur  Bank,  Calif.,  772. 
Sulphur,  in  coal,  10. 

production,  399. 

references,  400. 

types,  393. 

United  States,  396. 

uses,  399. 

Sumatra,  gold,  729. 
Sumatra  swamp,  peat  in,  12. 
Summerland,  Calif.,  102. 
Summerland  field,  Calif.,  104. 
Sumter,  S.  C.,  338. 
Sunnybrook  sand,  97. 
Sunset,  Calif.,  102. 
Supergene,  481. 
Sussex  County,  N.  J.,  626. 
Swain,  R.  E.,  788. 
Swanton,  Vt.,  153. 
Swartley,  A.  M.,  748. 
Sweden,  copper,  573;    granite,   164;    iron, 

517;  lead-silver,  659. 
Sweetwater  district,  N.  C.,  315. 
Switzerland,  marble,  164. 
Sydenham,  Ont.,  368. 
Sydney,  N.  S.,  coal  basin,  47. 
Sylvanite,  810. 

Syngenetic  ores,  sedimentary,  432. 
Syracuse,  N.  Y.,  226. 
Syracuse,  O.,  229. 


Tabbyite,  121. 

Taber,  S.,  498,  748,  822. 

Taberg,  Swe.,  524. 


Tacoma,  Wash.,  45. 

Taconite,  526. 

Taff,  J.  A.,  5,  66,  68,  122,  134,  137,  208. 

Tahoe  Lake,  211. 

Talc,  analyses,  409. 

Canada,  410. 

France,  410. 

occurrence,  407. 

origin,  407,  408. 

production,  411. 

properties,  407. 

references,  412. 

United  States,  407. 

uses,  410. 

Tampico,  Mex.,  111. 
Tantalite,  810. 

Tantalum,  occurrencce  and  use,  810. 
Tarr,  W.  A.,  80,  133,  620. 
Tarugi,  N.,  771. 
Tasmania,  copper,  614;    osmium,  808;    tin, 

811,  813,  816. 
Tasna,  Bolivia,  787. 
Taylor,  C.  H.,  422. 
Teil,  France,  189. 
Telluride  quadrangle,  Colo.,  724. 
Telluride  ores,  Colo.,  719. 
Tellurides,  gold,  677. 

weathering  of,  677. 
Tellurium,  810. 
Temple,  Utah,  826. 
Tenino,  Wash.,  8. 
Ten  Mile  district,  Colo.,  671. 
Tennantite,  568. 

Tennessee,  bauxite,  753;  clay,  180;  coal, 
34;  copper,  610;  fluorspar,  330;  lim- 
onite,  556;  manganese,  762,  766;  marble, 
153,  phosphate,  267;  tripoli,  413;  zinc, 
638. 

Terra  alba,  256. 
.  Terlingua,  Tex.,  765,  774. 
Tesla,  Cal.,  8,  46. 
Tetradymite,  686,  810. 
Tetrahedrite,  568,  676. 
Texada  Island,  B.  C.,  517,  547. 
Texas,  cement,  202;    clay,   180;    coal,  45; 
granite,  147,  148;    guano,  279;    gypsum, 
252;    limonite,   556;     mercury,   774;    pe- 
troleum, 103;   sulphur,  396. 
Thermopolis,  Wyo.,  397. 
Thetford,  Quo.,  298,  305. 
Thies,  A.,  748. 
Thiessen,  R.,  65. 
Thirty-foot  sand,  97. 
Thomas,  H.  H.,  497. 
Thomas,  K.,  400. 
Thompson,  A.  P.,  618. 
Thompson,  B.,  133. 
Thompson,  Jr.,  J.  D.,  26. 
Thompson,  M.,  168. 
Thomson,  S.  A.,  695. 
Three  Rivers,  Que.,  556. 
Thwaites,  F.  T.,  566. 
Ticonderoga,  N.  Y.,  344. 
Tiemannite,  771. 
Tietze,  O.,  125,  182,  255,  289,  316,  338,  355, 

364,  400,  412,  755. 
Tin,  Alaska,  815. 

contact  metamorphic  ores,  811. 
foreign  deposits,  816. 
Germany,  816. 


854 


INDEX 


Tin,  greisen,  812. 

hot  spring  deposits.  814. 
in  igneous  rocks,  811. 
mode  of  occurrence,  811. 
ore  minerals,  810. 
placers,  814. 
production,  818. 
references  on,  818. 
United  States,  814. 
uses,  818. 
value  of  ores,  489. 
veins,  811. 
Tincal,  233. 

Tintic  district,  Utah,  666. 
Tiona  sand,  97. 
Tip  Top,  Ky.,  341. 
Titanium,  Canada,  820. 

mode  of  occurrence,  819 
Norway,  821. 
ore  minerals,  819. 
production,  821. 
references  on,  822. 
United  States,  819. 
uses,  821. 

Tiverton,  R.  I.,  348. 
Todd,  J.  E.,  67,  168,  259. 
Tolman,  Jr.,  C.  F.,  477,  481,  498,  500,  601, 

618. 

Tonopah,  Nov.,  714,  809. 
Topaz,  gem,  385. 
Topeka,  Has.,  39. 
Torbanite,  125. 
Torbrook,  N.  S.,  547. 
Toronto,  Can.,  111. 
Tourmaline,  gem,  386. 
Tovote,  W.,  618. 
Tower,  G.  W.,  656,  666,  674. 
Tower  City,  Pa.,  9. 
Transbaikal,  copper,  605. 
Transvaal,  S.  Afr.,  737. 
Transylvania,  gold-silver,  729. 
Trap  rock,  148. 
Travertine,  defined,  150. 

for  building,  150. 

with  barite,  309. 

Tremolite,  forming  talc,  408. 

in  marble,  149. 
Trinidad,  asphalt,  121. 
Tripoli,  analyses,  413. 
definition,  412. 
origin,  413. 
references,  414. 
United  States,  412. 
uses,  414. 

Trousdale  County,  Tenn.,  330. 
Truscott,  S.  J.,  809. 
Tuff,  building  stone,  149. 
Tulameen,  Brit.  Col.,  807. 
Tulsa,  Okla.,  102. 
Tungsten,  Canada,  824. 

foreign  deposits,  824. 
mode  of  occurrence,  822. 
ore  minerals,  822. 
production,  824. 
references  on,  825. 
United  States,  823. 
uses,  824. 
Tungstite,  824. 
Tunis,  Afr.,  280. 
Turkey,  chromite,  792. 


Turner,  H.  W.,  499,  619,  746,  778. 
Turquoise,  gem,  386. 
Turrentine,  J.  W.,  243. 
Tuscany,  Italy,  233. 
Tuxpam,  Mex.,  111. 
Twelvetrees,  W.  H.,  809,  813. 
Type  metal,  651,  781. 
Tyson  coal,  32. 

U 

Udden,  J.  A.,  135,  243,  421,  748. 

Uglow,  W.  L.,  497. 

Uinta  basin  coals,  42. 

Uintaite,  121. 

Ulexite,  233. 

Ulrich,  E.  O.,  334,  335,  619,  656. 

Umpleby,  J.  B.,  674,  747,  805,  819. 

Underground  waters.      See  Waters. 

Upham,  W.,  185. 

Upper  Freeport  coal,  32. 

Ural  Mountains,  Russia,  307,  344. 

Uraninite,  825. 

Uranium,  foreign  deposits,  826. 
ore  minerals,  825. 
production,  827. 
United  States,  826. 
uses,  827. 

Usiglio,  J.,  212. 

Utah,  antimony,  780;  asphalts,  118,  121; 
bismuth,  786;  cement,  202;  coal,  44; 
copper,  580,  592;  gold,  692;  gold-silvtr. 
700;  gypsum,  252;  iron,  512,  516;  oil 
shale,  125;  manganese,  767;  phosphate, 
275;  potash,  242;  salt,  224;  selenium, 
809;  silver-lead,  664,  666;  sulphur,  396; 
topaz,  385;  uranium,  826;  vanadium, 
826. 

Utica,  111.,  190,  196,  198,  341. 

Uvanite,  825. 


Vadose  region,  437. 
Vadose  water,  441. 
Vanadinite,  825. 
Vanadium,  ore  minerals,  825. 
Peru,  827. 
production,  827. 
United  States,  826. 
uses,  827. 

Vancouver,  B.  C.,  162. 
Vancouver  Island,  Can.,  coal,  50. 
Van  Hise,  C.  R.,    437,    438,  482,  489,  497, 
498,   499,    534,    565,   619,   645, 
656,  771. 

Van  Ingen,  G.,  771. 
Van  't  Hoff,  J.  H.,  247. 
Variscite,  388. 
Vater,  H.,  247. 

Vaughan,  T.  W.,  68,  137,  340. 
Veatch,  A.  C.,  68,  135,  218,  228,  421,  422. 
J.  A.,  396. 
O.,  185,  758. 
Vegreville,  Alberta,  115. 
Vein  bitumens,  117. 
Vein  material,  466. 
Vein  systems,  471. 
Veins,  apex  of,  471. 
banded,  466. 
bedded,  472. 
bonanzas  in,  468. 


INDEX 


855 


Veins,  cross,  472. 

trustification  in,  466. 
filling  of   472. 
fissure,  466. 
foot  wall,  471. 
frozen  to  walls,  468. 
gash,  472. 
hanging  wall,  471. 
high  temperature,  447. 

classes  of,  447. 
horse  in,  471. 
lenticular,  472. 
lode,  471. 

replacement  in,  468. 
selvage  in,  468. 
splitting  of,  470. 
stringers,  471. 
structural  features,  468. 
Veinstone,  466. 
Veitsch,  Styria,  356. 
Velardena,  Mex.,  592. 
Vermilion  range,  532. 

Vermont,  asbestos,  300;    granite,  147;  man- 
ganese, 766;    marble,  152;    scythestones, 
287;   slate,  162. 
Verne  coal,  37. 
Vesuvius,  emanations,  444. 
Victoria,  gold,  705,  706. 

placers,  737. 
Virgilina,  Va.,  601. 
Virgin  Creek,  Nev.,  384. 
Virginia,  arsenic,  784;    asbestos,  301;    bar- 
ite,   312;     bauxite,   754;     building  stone, 
147;     clay,   179;     coal,   34;     copper,   601, 
611;    diatomaceous  earth,  320;    graphite, 
349;   greensand,  279 ;   gypsum,  252;   lead, 
638;    limonite,  550,  553;    magnetite,  515; 
manganese,  761;    mica,  367;    millstones, 
284;    natural  cement  rock,   196;    nickel, 
795;    phosphate,  278;    pyrite,  401;    salt, 
222;   soapstone,  407;   talc,  409;   titanium, 
820;   tufa,  150;    zinc,  638. 
Virginia  City,  Nev.,  687,  718. 
Vogt,  J.  H.  L.,  435,  440,  447,  451,  452,  497, 
498,  501,   524,  548,  603,  614,  659, 
672,  673,  705,  708,  729,  730,  775, 
803,  811,  813,  821. 
Volcanic  ash,  abrasive,  288,  289. 

for  cement,  189. 
Volcano,  emanations  from,  444. 


W 


Wabana,  N.  F.,  546. 

Wad,  758. 

Wadsworth,  O.,  239. 

Wadsworth,  M.  E.,  747. 

Wages  sand,  96. 

Waggaman,  W.  H.,  243,  262,  283. 

Wagoner,  L.,  435. 

Wagon  Wheel  Gap,  Colo.,  329. 

Waihi  mine,  N.  Z.,  729. 

Wales,  slate,  164. 

Walker,  T.  L.,  825. 

Wallace,  H.  V.,  771. 

Wllaace,  R.  C.,  259. 

Wallace,  Ido.,  660. 

Walther,  J.,  228. 

Wang,  Y.  T.,  480,  655. 

Waring,  G.  A.,  421,  422. 


Warners,  N.  Y.,  192,  203. 
Warren,  C.  H.,  318,  567,  822. 
Warren,  H.  L.  J.,  748. 
Warren  sand,  97. 
Warrior  coal  field,  35. 
Warsaw,  N.  Y.,  226. 
Washburne,  C.  W.,  85,  90,  91,  133,  134. 
Washington,  arsenic,  784;    building  stone, 
148;    coal,  45;    gold-silver,  729;    serpen- 
tine, 156. 

Washington,  H.  S.,  390,  501. 
Water,  artesian,  417. 
connate,  438. 
ground,  416. 

composition,  442. 
concentrator  of  metals  by, 

437. 

in  earth's  crust,  433. 
in  igneous  rocks,  441. 
magmatic,  440. 

meteoric,  in  ore  formation,  437,  441. 
mine,  442. 
mineral,  422. 

source  of  in  earth's  crust,  437. 
underground,  416. 
Waterford,  111.,  336. 
Water  gas,  analysis  of,  79. 
Water  table,  437. 
Watkins,  N.  Y.,  239. 

Watson,  T.  L.,   5,  68,    167,   168,  228,  259, 
260,    283,    297,    309,    313,    316, 
318,    327,    334,  337,    353,   370, 
377,    390,    406,  412,   422,    498, 
565,    619,   620,    656,    657,    748, 
750,    758,    771,     786,  805,  810, 
819,  821,  822. 
Watts,  W.  L.,  134,  135. 
Wausau,  Wis.,  147. 
Wavellite,  414. 
Weaver,  C.  E.,  748. 

Weed,    W.  H.,  66,  441,  442,  451,  482,  486, 
489,  499,    500,    618,    619,    620, 
674,  745   ,  747,  786. 
Weedon,  Que.,  404. 
Weeks,  F.  B.,  283,  825. 
Weems,  J.  B.,  185. 
Wegemann,  C.  H.,  135. 
Weidman,  S.,  422,  566. 
Weigert,  F.,  247. 
Weinschenk,  E.,  353,  573. 
Weld,  C.  M.,  566. 
Wells,  J.  W.,  499,  786. 
Wells,  R.  C.,  501. 
Wellston  coal,  32. 
Wellston,  O.,  9. 
Wendt,  A.,  406. 
Werner,  A.  G.,  672. 
Wesson,  D.,  340. 
West  Australia,  gold,  695. 
Westerley,  R.  I.,  147. 
West  Gore,  N.  S.,  780. 

West  Virginia,  asphalt,  118;  bromine,  229; 
calcium  chloride,  230;  clay,  179;  coal, 
34;  glass  sand,  342;  natural  gas,  114; 
oil,  94;  salt,  222. 

Wheaton  River  district,  Yuk.  Ty.,  780. 
Wheeler,  A.,  185. 

Wheeler,  H.  A.,  134,  184,  656,  781. 
Wherry,  E.  T.,  827. 
Whetstones,  287. 


856 


INDEX 


White,  D.,  13,  14,  16,  22,  65,  67. 

White,  I.  C.,  67,  68,  87,  133,  135,  137. 

White  Channel  gravels,  736. 

Wrhite  Cliffs,  Ark.,  192. 

Whitehorse,  Yuk.  Ty.,  592. 

White  metal,  651. 

White  sand,  731. 

Whiting,  376. 

Whitney,  J.  D.,  497. 

Whittle,  C.  L.,  185. 

Wichita  Mountains,  Okla.,  125,  147. 

Wieliczka,  Galicia,  225. 

Wilder,  F.,  67,  68,  228,  259. 

Wilkens,  H.  A.  J.,  748. 

Wilkinson  Co.,  Ga.,  753. 

Willemite,  621. 

Willey,  D.  A.,  400. 

Williams,  G.  F.,  382,  390. 

Williams,  G.  H.,  296. 

Williams,  I.  A.,  67,  168,  185,  186,  208,  209. 

Williston,  N.  Dak.,  43. 

Willmott,  A.  B.,  567. 

Willmott,  C.  W.,  825. 

Wilmot,  Va.,  319. 

Wilson,  A.  W.  G.,  406. 

Wilson,  M.  E.,  749. 

Wilson  County,  Tenn.,  330. 

Winchell,  A.,  185,  564,  825. 

Winchell,  A.  N.,  353,  619. 

Wir.chell,  H.  V.,  475,  499,  501,  747. 

Winchester,  Calif.,  357. 

Winnipeg,  Can.,  164. 

Winslow,  A.,  66,  435,  566,  645,  656. 

Wisconsin,  artesian  water,  418;  building 
stone,  147,  149,  158;  lead-zinc,  648;  lim- 
onite,  556;  natural  cement  rock,  196; 
pyrite,  403;  quartz,  391. 

Wise  Co.,  Va.,  9. 

Witherbee,  F.  S.,  509. 

Wittlich,  E.,  813. 

Witwatersrand,  S.  Afr.,  737. 

Woburn  Sands,  Eng.,  338. 

Wochein,  Ger.,  751. 

Wolff,  J.  E.,  565,  656. 

Wolframite,  822. 

Wolframinium,  756. 

Woodman,  J.  E.,  567. 

Wood  River,  Ido.,  453. 

Woodruff,  E.  G.,  135,  136,  400. 

Woodstock,  Md.,  323. 

Wood  tin,  811. 

Woodworth,  J.  B.,  67,  68,  185. 

Woolsey,  L.  H.,  297. 


Wright,  C.  A.,  657. 

Wright,  C.  W.,  107,  259,  558,  618. 

Wright,  F.  C.,  447. 

Wright.  F.  E.,  192,  501,  618. 

Wulfenite,  793. 

Wurtzilite,  121. 

Wurtzite,  621. 

Wyoming,  asbestos,  302;  coal,  42;  chro- 
mite,  791;  gypsum,  252;  graphite,  349; 
iron,  522,  536;  petroleum,  109;  phos- 
phate, 275;  platinum,  806;  sodium  sul- 
phate, 231;  sulphur,  397;  volcanic  ash, 
290. 

Wyssokaia  Gora,  Russia,  518. 


YakutatBay,  Alas.,48. 
Yale,  C.  G.,  237,  745. 
Yampa  coal  field,  Colo.,  42. 
Yellow  Pine  district,  Nev.,  806. 
Yellow  sand,  731. 
Yerington,  Nev.,  586. 
Yogo  Gulch,  Mont.,  301. 
York,  Ont.,  253. 
York  region,  Alas.,  815. 
Yorkshire,  Eng.,  559. 
Young,  G.  A.,  567,  771,  783. 
Young,  G.  J.,  243,  747. 
Yukon  basin,  Alas.,  48. 

Yukon  Territory,  antimony,  780;    coal,  52; 
copper,  592;   gold,  736. 


Zacatecas,  Mex.,  730. 

Zalinski,  E.  R.,  390,  657. 

Zaloziecki,  R.,  81. 

Zanesville,  O.,  336. 

Zeehan  district,  Tasmania,  811,  813. 

Ziegler,  V.,  819. 

Zinc,  ore  minerals,  621. 

oxide,  652. 

production,  652. 

uses,  651. 

value  of  ores,  488. 
Zinc.     See  also  Lead-Zinc. 
Zincite,  621. 
Zinc  ores,  origin,  Missouri,  644. 

secondary  enrichment,  485. 
weathering,  480,  481. 
Zinnwald,  Ger.,  816. 
Zuber,  137. 


u 


